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Management and assessment of financial risks	12 Months Ended
Management and assessment of financial risks	Dec. 31, 2023
Financial Risk Management [Abstract]
Management and assessment of financial risks	Management and assessment of financial risks The principal financial instruments held by the Group are cash and cash equivalents. The purpose of holding these instruments is to finance the ongoing business activities of the Group. It is not the Group’s policy to invest in financial instruments for speculative purposes. The Group does not use derivative financial instruments for hedging purposes. The principal risks to which the Group is exposed to are liquidity risk, interest rate risk, foreign currency exchange risk, credit risk and fair value risk. Liquidity risk Liquidity risk management aims to ensure that the Group disposes of sufficient liquidity and financial resources to be able to meet present and future obligations. The Group prepares short-term cash forecasts and annual operating cash flow forecasts as part of its budget procedures. Prudent liquidity risk management involves maintaining sufficient liquidity, having access to financial resources through appropriate credit facilities and being able to unwind market positions. The Group’s operations have consumed substantial amounts of cash since inception. Developing pharmaceutical drug candidates, including conducting clinical trials, is expensive, lengthy and risky, and the Group expects its research and development expenses to increase substantially in connection with its ongoing activities. Accordingly, the Group will continue to require substantial additional capital to continue its clinical development activities and potentially engage in commercialization activities. The Group's estimate of its cash runway as of the date of approval of these financial statements is set forth in Note 2 - Going concern. Interest rate risk The Group is exposed to market risks in connection with its medium and long-term borrowings subject to variable interest rates. Due to fluctuations in market interest rates and the refinancing of most of its indebtedness over the year ended December 31, 2023, the Group has performed a reassessment of its exposure to interest rate risk. As of December 31, 2023, following the full repayment of the Kreos 1 bonds, all the Group’s non-derivative financial liabilities accounted for at amortized cost bear fixed interest rates. Therefore, the Group has limited exposure. The Group may reassess its exposure after the potential future drawdowns of the tranches B and C and the Kreos/Claret Financing, which bear variable interest rates. Foreign currency risk The Group is exposed to a risk of exchange rates fluctuations on commercial transactions performed in currencies different from the functional currency of the Group entity recording the transactions. For the years ended December 31, 2023, 2022 and 2021, expenses in U.S. dollars totaled €10,112 thousands, €1,390 thousands and €1,262 thousands respectively, based on the average annual exchange rate in effect as of December 31, 2023, December 31, 2022 and December 31, 2021. As a result, an adverse 10% change in the exchange rate for the U.S. dollar against the euro would have resulted in a foreign exchange rate loss of approximately €386 thousand for 2023 and non material amounts for the others periods. At this stage, the Group has not adopted any other recurring mechanism of hedging to protect its activity against currency fluctuations. From time to time, the Group may nevertheless subscribe currency term accounts in order to cover a commitment in currency as described above. The Group may consider in the future using a suitable policy to hedge exchange risks in a more significant manner if needed. Credit risk The credit risk related to the Group’s cash and cash equivalents is not significant in light of the quality of the co-contracting financial institutions. As of December 31, 2023, substantially all of the Group’s cash and cash equivalents were maintained with two financial institutions in France and in the United States. While the Group’s deposit accounts are insured up to the legal limit, the maintained balances may, at times, exceed this insured limit. As of December 31, 2023, the Group maintained €251,616 thousand in bank deposit accounts that are in excess of the legally insured limit in two legally insured financial institutions. The Group has not experienced any losses in such accounts and does not believe that it is exposed to any significant credit risk related to these instruments. The credit risk related to the Group’s other receivables and related account is minimal. In particular, the credit risk related to advances made to CROs (see Note 9) is deemed insignificant due to their credit ratings.

Retirement benefit obligations

12 Months Ended

Dec. 31, 2023

Disclosure of defined benefit plans [abstract]

Retirement benefit obligations

Retirement benefit obligations include the liability for the defined benefit plan, measured based on the provisions stipulated

under the applicable collective agreements, i.e. the French pharmaceutical industry’s collective agreement. This commitment

only applies to employees subject to French law. The main actuarial assumptions used to measure the retirement benefit

obligations are as follows:


ACTUARIAL ASSUMPTIONS	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Retirement age	65 years for key management / 63 years for other employees	65 years for key management / 63 years for other employees	65 years for key management / 64 years for other employees
Collective agreement	Pharmaceutical industry	Pharmaceutical industry	Pharmaceutical industry
Discount Rate (IBoxx Corporates AA)	0.90%	3.65%	3.34%
Mortality rate table	INSEE 2016-2018	INSEE 2016-2018	INSEE 2016-2018
Salary increase rate	3.00% for key management / 2.55% for other employees	3.00% for key management / 2.55% for other employees	3.00%
Turnover rate	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old
Employee contribution rate	45%	45%	45%

Changes in the projected benefit obligation for the periods presented were as follows:


(amounts in thousands of euros)	RETIREMENT BENEFIT OBLIGATIONS
AS OF JANUARY 1, 2021	745
Service cost	166
Interest cost	4
Benefits paid	(53)
Actuarial gains and losses	(169)
AS OF DECEMBER 31, 2021	693
Service cost	143
Interest cost	8
Benefits paid
Actuarial gains and losses	(235)
AS OF DECEMBER 31, 2022	610
Service cost	109
Interest cost	23
Benefits paid
Actuarial gains and losses	(112)
AS OF DECEMBER 31, 2023	629

Employees in the U.S. benefit from defined contribution plans (401(k)).

Operating income - Disclosure of breakdown of operating income (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue [abstract]
Research tax credit ("CIR")	€ 4,493	€ 4,476	€ 4,204
Subsidies	81	29	7,722
Other	47	78	36
Total operating income	€ 4,621	€ 4,583	€ 11,961

Share-based payments (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangements [Abstract]

Disclosure of reconciliation of other equity instruments



	NUMBER OF BSAs OUTSTANDING	MAXIMUM NUMBER OF SHARES TO BE ISSUED	NUMBER OF BSAs EXERCISED	NUMBER OF BSAs LAPSED	NUMBER OF BSAs OUTSTANDING	MAXIMUM NUMBER OF SHARES TO BE ISSUED

			FOR THE YEAR ENDED
	AS OF DECEMBER 31, 2021		DECEMBER 31, 2022		AS OF DECEMBER 31, 2022
BSAs granted under the Equity line agrement ......................................	300,000	300,000	—	(300,000)	—	—

The following tables summarize the data relating to BCEs as well as the assumptions used for the measurement thereof in accordance

with IFRS 2 – Share-based Payment:


GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BCEs	NUMBER OF EXERCISED BCEs	NUMBER OF BCEs OUTSTANDI NG	NUMBER OF BCEs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITION S ARE MET
GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BCE-2014-2	2,750	1,000	—	(1,000)	—	—	—
2014-03-11	BCE-2014-4	984	184	—	(184)	—	—	—
2016-11-07	BCE-2016-1	84,000	22,495		—	22,495	22,495	22,495
2017-01-23	BCE-2017-1	67,374	67,000	—	—	67,000	41,735	67,000
2017-11-20	BCE-2017-2	150,000	150,000	(37,500)	—	112,500	112,500	112,500
2017-11-20	BCE-2017-4	67,374	67,373	—	—	67,373	33,686	67,373
2017-11-20	BCE-2017-5	67,374	64,374	—	—	64,374	30,686	64,374
2018-03-15	BCE-2018-1	22,000	11,980		—	11,980	11,980	11,980
2018-05-14	BCE 2018-3	33,687	16,844	—	—	16,844	—	16,844
2018-05-14	BCE-2018-4	16,843	16,843	0	—	16,843	8,422	16,843
2018-05-14	BCE-2018-5	22,000	6,000			6,000	6,000	6,000
	Total BCEs	534,386	424,093	(37,500)	(1,184)	385,409	267,504	385,409

The following tables summarize the data relating to BSAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BSAs	NUMBER OF EXERCISED BSAs	NUMBER OF BSAs OUTSTANDI NG	NUMBER OF BSAs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITIONS ARE MET
GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BSA-2014-3	1,172	492	—	(492)	—	—	—
2015-12-04	BSA-2015-11	96,924	96,924	—	—	96,924	96,924	96,924
2015-12-04	BSA-2015-12	82,000	16,400	—	—	16,400	16,400	16,400
2017-09-18	BSA-2017-1	16,400	16,400	—	—	16,400	16,400	16,400
2018-01-22	BSA-2018-1	49,200	16,400	—	—	16,400	16,400	16,400
2014-03-11	BSA-2014-4	1,315	842	—	—	842	842	84,160
2014-03-11	BSA-2014-5	787	459	—	(230)	230	230	22,950
	Total BSAs	247,798	147,917	—	(722)	147,196	147,195	253,234

The following tables summarize the data relating to AGAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	NUMBER OF AGAs OUTSTANDING
GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	AS OF DECEMBER 31, 2023
2023-07-11	AGA-2023-1	1,382,796	—	—	—	1,382,796
2023-07-11	AGA-2023-2	100,000	—	—	—	100,000
2023-09-28	AGA-2023-3	731,500	—	—	—	731,500
2023-09-28	AGA-2023-4	254,250	—	—	—	254,250
2023-12-01	AGA-2023-5	132,750	—	—	—	132,750
	Total AGAs	2,601,296	—	—	—	2,601,296

Disclosure of main data and assumptions used for the measurement of other equity instruments


TYPE	FAIR VALUE OF THE UNDERLYING SHARE	FAIR VALUE OF THE AGA	AGA PRICE	MATURITY	VOLATILITY	RISK FREE RATE
AGA 2021	€31.60	€23.92	0.00 €	2022-07-31	49.0%	-1.00%
AGA 2023-1 (Tranches 1-4)	€15.98	€15.98	0.00 €	N/A	N/A	N/A
AGA 2023-1 (Tranche 5)	€15.98	€3.62	0.00 €	2024-12-31	67.2%	3.20%
AGA 2023-1 (Tranche 6)	€15.98	€0.74	0.00 €	2024-07-11	67.2%	3.20%
AGA 2023-2 (Tranche 1)	€15.98	€15.98	0.00 €	N/A	N/A	N/A
AGA 2023-2 (Tranche 2)	€15.98	€9.59	0.00 €	N/A	N/A	N/A
AGA 2023-3	€14.92	€14.92	0.00 €	N/A	N/A	N/A
AGA 2023-4	€14.92	€14.92	0.00 €	N/A	N/A	N/A
AGA 2023-5	€9.16	€9.16	0.00 €	N/A	N/A	N/A

The

main data and assumptions are the following:


Kreos/Claret Tranche A-B BSA - August 2023	AS OF AUGUST 22, 2023 (Tranche A-B)	AS OF DECEMBER 31, 2023
Number of outstanding BSA	214,198	214,198
Exercise price per share	€18.67	€18.67
Ordinary share price	€17.10	€9.82
Exercise date	19/08/2030 (expiry) 18/02/2027 (tender offer)	19/08/2030 (expiry) 18/02/2027 (tender offer)
7-year expiry scenario probability	50%	95%
Volatility	71.9% (expiry) 65.2% (tender offer)	59.5% (expiry) 64.9% (tender offer)
Dividend	—%	—%
Risk-free rate	3.00%	2.30%
Fair value of issued Kreos/Claret Tranche A-B BSA	2,092	920


Kreos/Claret Tranche C BSA - November 2023	AS OF NOVEMBER 2, 2023	AS OF DECEMBER 31, 2023
Number of outstanding BSA	405,832	405,832
of which, number of conditional BSA	202,915	202,915
Exercise price per share	€9.86	€9.86
Ordinary share price	€8.89	€9.82
Exercise date	01/11/2030 (expiry) 18/02/2027 (tender offer)	01/11/2030 (expiry) 18/02/2027 (tender offer)
7-year expiry scenario probability	95%	95%
Probability of Drawdown of Tranche C credit facility	30%	30%
Volatility	67.3% (expiry) 64.3% (tender offer)	67.4% (expiry) 64.9% (tender offer)
Dividend	—%	—%
Risk-free rate	3.0%	2.3%
Fair value of issued Kreos/Claret Tranche C BSA	1,493	1,659

The Kreos A BSA and Kreos B BSA are measured at fair value using a Black-Scholes valuation model. The main data and

assumptions are the following:


Kreos A BSA - June 1, 2018	As of and for the year ended December 31, 2021	As of and for the year ended December 31, 2022	As of May 24, 2023 (exercise date)
Number of outstanding Kreos A BSA	110,957	110,957	110,957
Exercise price per share	€7.21	€7.21	€7.21
Ordinary share price	€28.55	€6.18	€18.57
Residual maturity	6.6 years	5.6 years	0.0 years
Volatility	46.65%	44.01%	N/A
Dividend	—%	—%	N/A
Risk-free rate	0.13%	2.98%	N/A
Fair value of issued Kreos A BSA (in thousands of €)	2,478	275	1,261


Kreos B BSA - June 1, 2019	As of and for the year ended December 31, 2021	As of and for the year ended December 31, 2022	As of May 24, 2023 (exercise date)
Number of outstanding Kreos B BSA	74,766	74,766	74,766
Exercise price per share	€10.70	€10.70	€10.70
Ordinary share price	€28.55	€6.18	€18.57
Residual maturity	7.4 years	6.4 years	0.0 years
Volatility	46.65%	44.01%	N/A
Dividend	—%	—%	N/A
Risk-free rate	0.13%	2.96%	N/A
Fair value of issued Kreos B BSA (in thousands of €)	1,525	149	589

Disclosure of breakdown of the compensation expenses

Breakdown of the compensation expenses accounted for the period ended December 31, 2021, 2022 and 2023


TYPE (in thousands of euros)	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
BCEs	(199)	(138)	(112)
BSAs	—	—	—
AGAs	1,026	(1,026)	(8,067)
Social taxes related to AGAs	205	(205)	(426)
Total	1,032	(1,369)	(8,605)

Employees

12 Months Ended

Dec. 31, 2023

Employees [Abstract]

Employees

The Group’s average workforce during the periods ended December 31, 2021, 2022 and 2023 was as follows:


HEADCOUNTS	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
France	27	23	28
United States	—	—	12
Total	27	23	40

Income (loss) per share - Narrative (Details)	12 Months Ended
Income (loss) per share - Narrative (Details)	Dec. 31, 2023 shares	Dec. 31, 2022 shares	Dec. 31, 2021 shares
Earnings per share [abstract]
Number of instruments that are antidilutive in period presented (in shares)	28,754,280	1,707,037	1,873,216
Maximum number of shares to be issued (in shares)	6,510,658	1,707,037	2,186,551

Operating income - Narrative (Details) - EUR (€) € in Thousands	1 Months Ended		8 Months Ended	12 Months Ended
	Oct. 31, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure Of Operating Income [Line Items]
Research tax credit ("CIR")				€ 4,493	€ 4,476	€ 4,204
Covid-19 conditional advance
Disclosure Of Operating Income [Line Items]
Proceeds from conditional advances		€ 4,459	€ 6,300
Proceeds from government grants	€ 3,279

Intangible assets - Disclosure of reconciliation of intangible assets (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	€ 6,607	€ 93	€ 97
Intangible assets other than goodwill at end of period	6,604	6,607	93
LICENCES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	75	85	85
Intangible assets other than goodwill at end of period	75	75	85
SOFTWARES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	3	8	12
Intangible assets other than goodwill at end of period	0	3	8
PATENTS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	6,529	0	0
Intangible assets other than goodwill at end of period	6,529	6,529	0
OTHER INTANGIBLE ASSETS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	0	0	0
Intangible assets other than goodwill at end of period	0	0	0
GROSS VALUES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	6,673	110	110
Acquisition	0	6,564	0
Disposal	0	0	0
Transfer	0	0	0
Intangible assets other than goodwill at end of period	6,673	6,673	110
GROSS VALUES \| LICENCES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	120	85	85
Acquisition	0	35	0
Disposal		0	0
Transfer		0	0
Intangible assets other than goodwill at end of period	120	120	85
GROSS VALUES \| SOFTWARES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	24	24	24
Acquisition	0	0	0
Disposal		0	0
Transfer		0	0
Intangible assets other than goodwill at end of period	24	24	24
GROSS VALUES \| PATENTS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	6,529	0
Acquisition		6,529	0
Disposal		0	0
Transfer	0	0	0
Intangible assets other than goodwill at end of period	6,529	6,529	0
GROSS VALUES \| OTHER INTANGIBLE ASSETS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	0	0
Acquisition	0		0
Disposal		0	0
Transfer		0	0
Intangible assets other than goodwill at end of period	0	0	0
AMORTIZATION
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(66)	(17)	(12)
Increase	(2)	(50)	(4)
Decrease	0	0	0
Intangible assets other than goodwill at end of period	(69)	(66)	(17)
AMORTIZATION \| LICENCES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(45)	0	0
Increase	0	(45)	0
Decrease	0	0	0
Intangible assets other than goodwill at end of period	(45)	(45)	0
AMORTIZATION \| SOFTWARES
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(21)	(17)	(12)
Increase	(3)	(4)	(4)
Decrease	0	0	0
Intangible assets other than goodwill at end of period	(24)	(21)	(17)
AMORTIZATION \| PATENTS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	0	0
Increase	0	0	0
Decrease	0	0	0
Intangible assets other than goodwill at end of period	0	0	0
AMORTIZATION \| OTHER INTANGIBLE ASSETS
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	0	0
Increase	0	0	0
Decrease	0	0	0
Intangible assets other than goodwill at end of period	€ 0	€ 0	€ 0

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY - EUR (€) € in Thousands	Total	Equity line agreement share warrants	Kreos share warrants	Other equity agreement	SHARE CAPITAL	SHARE CAPITAL Equity line agreement share warrants	SHARE CAPITAL Kreos share warrants	SHARE CAPITAL Other equity agreement	PREMIUMS RELATED TO SHARE CAPITAL	PREMIUMS RELATED TO SHARE CAPITAL Equity line agreement share warrants	PREMIUMS RELATED TO SHARE CAPITAL Kreos share warrants	PREMIUMS RELATED TO SHARE CAPITAL Other equity agreement	TRANSLATION RESERVE	RETAINED EARNINGS	NET LOSS FOR THE YEAR
Number of shares issued at beginning of period (in shares) at Dec. 31, 2020	14,320,271
Reconciliation of number of shares outstanding [abstract]
Capital increase from issuance of ordinary shares (in shares)	1,964,031
Exercises of share warrants (in shares)		312,000		167,749
Number of shares issued at end of period (in shares) at Dec. 31, 2021	16,764,051
Equity at beginning of period at Dec. 31, 2020	€ 1,733				€ 143				€ 42,073				€ 0	€ (2,851)	€ (37,633)
Changes in equity [abstract]
Net loss for the period	(42,452)														(42,452)
Other comprehensive income (loss)	169													169
Total comprehensive income (loss) for the period	(42,283)													169	(42,452)
Appropriation of prior period net loss	0													(37,633)	37,633
Capital increase from issuance of ordinary shares	60,001				20				59,982
Transaction costs related to capital increase	(4,090)								(4,090)
Exercises of share warrants		€ 8,097		€ 1,522		€ 3		€ 2		€ 8,094		€ 1,520
Shares based compensation expense	828													828
Transaction on treasury shares	126													126
Equity at end of period at Dec. 31, 2021	€ 25,934				168				107,578				0	(39,361)	(42,452)
Reconciliation of number of shares outstanding [abstract]
Capital increase from issuance of ordinary shares (in shares)	5,530,000
Exercises of share warrants (in shares)	19,134
Number of shares issued at end of period (in shares) at Dec. 31, 2022	22,313,185
Changes in equity [abstract]
Net loss for the period	€ (60,740)														(60,740)
Other comprehensive income (loss)	235													235
Total comprehensive income (loss) for the period	(60,506)													235	(60,740)
Appropriation of prior period net loss	0													(42,452)	42,452
Capital increase from issuance of ordinary shares	46,231				55				46,176
Transaction costs related to capital increase	(3,280)								(3,280)
Exercises of share warrants	3								2
Shares based compensation expense	(1,164)													(1,164)
Transaction on treasury shares	(28)													(28)
Equity at end of period at Dec. 31, 2022	€ 7,189				223				150,476				0	(82,770)	(60,740)
Reconciliation of number of shares outstanding [abstract]
Capital increase from issuance of ordinary shares (in shares)	40,325,500
Exercises of share warrants (in shares)			99,583	190,550
Number of shares issued at end of period (in shares) at Dec. 31, 2023	62,928,818
Changes in equity [abstract]
Net loss for the period	€ (147,740)														(147,740)
Other comprehensive income (loss)	225												112	112
Total comprehensive income (loss) for the period	(147,516)												112	112	(147,740)
Appropriation of prior period net loss	0													(60,740)	60,740
Capital increase from issuance of ordinary shares	353,377				403				352,974
Transaction costs related to capital increase	(28,111)								(28,111)
Exercises of share warrants			€ 1,850	€ 2			€ 1	€ 2			€ 1,849
Issue of convertible notes	1,030								1,030
Shares based compensation expense	8,179													8,179
Transaction on treasury shares	10													10
Equity at end of period at Dec. 31, 2023	€ 196,010				€ 629				€ 478,218				€ 112	€ (135,209)	€ (147,740)

CONSOLIDATED STATEMENTS OF CASH FLOWS
€ in Thousands, $ in Millions

12 Months Ended

Dec. 31, 2023

EUR (€)

Dec. 31, 2022

EUR (€)

Dec. 31, 2021

EUR (€)

Cash flows used in operating activities

Net loss for the period

€ (147,740)

€ (60,740)

€ (42,452)

Ajustments for:

Elimination of amortization of intangibles and depreciation of property, plant and equipment

707

485

302

Elimination of Impairment loss of goodwill

13,632

Elimination of retirement benefit obligations

109

143

117

Elimination of share-based compensation expenses

8,179

(1,164)

828

Net gain on sale of treasury shares

(34)

(108)

Interest expenses and other financial expenses

24,827

7,028

3,561

Financial income

(2,953)

(288)

Effect of unwinding the discount related to advances

(355)

(2)

1,939

Increase/(decrease) in derivatives and liabilities fair value

(1,158)

(10,817)

(2,427)

Forgiveness of Covid 19 conditional advances

(6,348)

Other

(100)

Cash flows used in operating activities before change in working capital requirements

(118,395)

(51,933)

(44,381)

Decrease / (increase) in other receivables and other assets

(14,231)

312

(1,977)

Increase / (decrease) in trade payables

31,757

(2,388)

1,141

Increase / (decrease) in tax and social security liabilities

3,821

100

209

Increase / (decrease) in deferred income and other liabilities

(81)

(26)

(41)

Changes in working capital requirements

21,265

(2,002)

(667)

Cash flows used in operating activities

(97,130)

(53,936)

(45,048)

Cash flows used in investing activities

Acquisitions of intangible assets

(35)

Acquisitions of property, plant and equipment

(265)

(288)

(47)

Advance made to CROs

(1,620)

(12,187)

Payments for the acquisition of Prosynergia, incl. related costs, net of cash acquired

^[1]

(2,913)

(2,176)

Increase in Deposits and other financial assets

(9,351)

(142)

(9)

Decrease in Deposits

741

218

Repayment / (disbursement) of the advance made to the Nice CHU

3,302

(4,000)

Interest received

2,400

Cash flows used in investing activities

(8,095)

(12,026)

(6,232)

Cash flows provided by (used in) financing activities

Capital increases

353,377

46,231

69,683

Transaction costs related to capital increase

(28,111)

(3,280)

(4,153)

Warrants subscription

Repayments of KREOS 1&2 bond loans

^[2]

(11,635)

(9,410)

(5,537)

Repayments of convertible loan notes

(27,188)

Net proceeds from convertible loan notes

55,841

24,913

Repayment of PGE

(1,250)

Net proceeds from sale of royalty certificate

2,931

Net proceeds from sale of treasury shares

143

Repayments of conditional advances

(110)

(90)

(70)

Payments of the lease liabilities

(529)

(301)

(249)

Interest paid

(5,279)

(4,015)

(1,908)

Other

160

Cash flows provided by (used in) financing activities

335,290

32,211

82,679

Effect of movements in exchange rates on cash held

(5,072)

Increase (decrease) in cash and cash equivalents

224,992

(33,751)

31,399

Cash and cash equivalents at the beginning of the year

26,950

60,701

29,302

Cash and cash equivalents at the end of the year

€ 251,942

€ 26,950

€ 60,701

[1]	Prosynergia SARL (or "Prosynergia")
[2]	Kreos Capital V UK Ltd (or "Kreos")

Intangible assets - Narrative (Details) - EUR (€) € in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 01, 2022
Prosynergia
Disclosure of detailed information about intangible assets [line items]
Patents					€ 6,529
Exclusive licensing contract with the Scripps Research Institute, University of Chicago and Brigham Young University
Disclosure of detailed information about intangible assets [line items]
Collaboration agreements, development milestone payment, IND approval	€ 45
Exclusive licensing agreement with CNRS, University of Montpellier and Institut Curie
Disclosure of detailed information about intangible assets [line items]
Collaboration agreements, development milestone payment, Phase 2	€ 40
Wittycel SAS
Disclosure of detailed information about intangible assets [line items]
Intangible assets with indefinite useful life			€ 0
Impairment loss recognised in profit or loss, other intangible assets		€ 0	€ 45	€ 0

Financial liabilities - Change in derivative instruments (Details) - EUR (€) € in Thousands		12 Months Ended
	May 24, 2023	Dec. 31, 2022
Disclosure of financial liabilities [abstract]
Exercises of share warrants	€ 1,850	€ 3

Operating income (Tables)

12 Months Ended

Dec. 31, 2023

Revenue [abstract]

Disclosure of breakdown of operating income

Operating income is composed as below:


(amounts in thousands of euros)
OPERATING INCOME	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Research tax credit ("CIR")	4,204	4,476	4,493
Subsidies	7,722	29	81
Other	36	78	47
Total operating income	11,961	4,583	4,621

Financial liabilities - Disclosure of financial liabilities breakdown (Details) - EUR (€) € in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	€ 60,349	€ 35,573	€ 50,240
Current financial liabilities	16,696	14,224	11,345
Total financial liabilities	77,045	49,797	61,585
Borrowings
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	2,563	9,127	16,458
Current financial liabilities	1,655	10,077	9,608
Kreos 1 & 2 bond loans
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	0	4,730	11,700
Current financial liabilities	0	8,252	9,410
Lease liabilities
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	160	839	43
Current financial liabilities	379	545	170
PGE
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	2,402	3,558	4,715
Current financial liabilities	1,276	1,280	27
Convertible loan notes
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	42,295	19,332	18,191
Current financial liabilities	8,952	625	625
Oceane
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	0	19,332	18,191
Current financial liabilities	0	625	625
Heights convertible notes
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	20,652	0	0
Current financial liabilities	8,952	0	0
Kreos / Claret convertible notes (OCABSA)
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	21,643	0	0
Derivative instruments
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	0	566	9,932
Current financial liabilities	2,579	0	0
Kreos A & B BSA
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	0	424	4,003
Oceane conversion option
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	0	142	5,929
Kreos / Claret BSA
Disclosure of detailed information about borrowings [line items]
Current financial liabilities	2,579	0	0
Other financial liabilities
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	15,491	6,549	5,659
Current financial liabilities	3,509	3,521	1,112
Conditional advances Bpifrance
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	3,262	3,262	5,659
Current financial liabilities	3,509	3,521	1,112
Royalty certificates
Disclosure of detailed information about borrowings [line items]
Non-current financial liabilities	12,229	3,287	0
Prosynergia earn-out liability
Disclosure of detailed information about borrowings [line items]
Current financial liabilities	€ 0	0	€ 0
Total financial liabilities		€ 0

Share-based payments - Disclosure of reconciliation of AGAs (Details) - shares				6 Months Ended		12 Months Ended
	Dec. 01, 2023	Sep. 28, 2023	Jul. 11, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023
Total AGAs
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)				2,601,296	2,601,296
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				2,601,296	2,601,296	2,601,296
AGA-2023-1
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)			1,382,796
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				1,382,796	1,382,796	1,382,796
AGA-2023-2
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)			100,000
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				100,000	100,000	100,000
AGA-2023-3
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)		731,500
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				731,500	731,500	731,500
AGA-2023-4
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)		254,250
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				254,250	254,250	254,250
AGA-2023-5
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)	132,750
Number of instruments outstanding, beginning balance (in shares)						0
Number of instruments lapsed (in shares)						0
Number of instruments exercised (in shares)						0
Number of instruments outstanding, ending balance (in shares)				132,750	132,750	132,750

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of comprehensive income [abstract]
Net loss for the period	€ (147,740)	€ (60,740)	€ (42,452)
Items that will not be reclassified to profit or loss	112	235	169
Actuarial gains and losses on retirement benefit obligations	112	235	169
Items that are or may be reclassified subsequently to profit or loss	112	0	0
Foreign currency translation differences	112	0	0
Other comprehensive income (loss)	225	235	169
Total comprehensive income (loss) for the period	€ (147,516)	€ (60,506)	€ (42,283)

- Definition

The amount of change in equity resulting from transactions and other events, other than those changes resulting from transactions with owners in their capacity as owners.

+ References + Details

- Definition

The total of income less expenses from continuing and discontinued operations, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2023-01-01
-Paragraph 18
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2023-en-r&anchor=para_18_b&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2023-01-01
-Paragraph 32
-Subparagraph a
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=1&code=ifrs-tx-2023-en-r&anchor=para_32_a_ii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2023-01-01
-Paragraph 24
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=1&code=ifrs-tx-2023-en-r&anchor=para_24_b&doctype=Standard
-URIDate 2023-03-23

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 28
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_28_b&doctype=Standard
-URIDate 2023-03-23

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 23
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_23&doctype=Standard
-URIDate 2023-03-23

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph B10
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_B10_b&doctype=Appendix&subtype=B
-URIDate 2023-03-23

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 17
-IssueDate 2023-01-01
-Paragraph 113
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=17&code=ifrs-tx-2023-en-r&anchor=para_113_b&doctype=Standard
-URIDate 2023-03-23

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 81A
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_81A_a&doctype=Standard
-URIDate 2023-03-23

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 106
-Subparagraph d
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_106_d_i&doctype=Standard
-URIDate 2023-03-23

+ Details

Operating income

12 Months Ended

Dec. 31, 2023

Revenue [abstract]

Operating income

Operating income is composed as below:


(amounts in thousands of euros)
OPERATING INCOME	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Research tax credit ("CIR")	4,204	4,476	4,493
Subsidies	7,722	29	81
Other	36	78	47
Total operating income	11,961	4,583	4,621

Operating income is composed as follows:

Research tax credit (“CIR”)

The Group carries out research and development projects. As such, it has benefited from a research tax credit for the years ended

December 31, 2021, 2022 and 2023 for an amount of €4,204 thousand, €4,476 thousand and €4,493 thousand, respectively (see Note

4.9).

Subsidies

Subsidy income primarily relates to Bpifrance agreement to finance the “COVID-19” project. This financing was granted under the

French Future Investments Project. This study was conducted with the participation of the University Hospital of Nice, which directly

manages part of the financing of the COVID-19 clinical trial.

For the year ended December 31, 2021, the Group recognized as a subsidy: (i) €4,459 thousand corresponding to the conditional

advance received in June 2020 (discounted amount) which had been waived by Bpifrance in April 2021 (See Note 15.7, “Conditional

advances”), and (ii) an additional payment of €3,279 thousand received in October 2021 to reimburse additional expenses incurred

until the termination date.

Financial gain (loss) (Tables)

12 Months Ended

Dec. 31, 2023

Financial Income (Loss) [Abstract]

Disclosure of net financial income (loss)

The financial loss breaks down as follows:


(amounts in thousands of euros)
FINANCIAL GAIN (LOSS)	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Interest on Kreos 1 & 2 straight bond loans	(2,344)	(3,737)	(760)
Interest on convertible loan notes	(1,064)	(2,641)	(3,935)
Interest on conditional advances	(145)	(196)	(176)
Interest on royalty certificates	—	(356)	(8,942)
Interest on lease liabilities	(5)	(10)	(13)
Increase in derivatives fair value	—	—	(3,046)
Loss on derecognition of financial liabilities	—	—	(3,431)
Transaction costs	—	—	(1,924)
Foreign exchange losses	—	—	(5,573)
Other	(2)	(83)	(73)
Financial expenses	(3,561)	(7,022)	(27,875)
Interest income	—	—	2,418
Decrease/(increase) in derivatives fair value	2,425	9,366	1,006
Decrease/(increase) in other liabilities at fair value through profit and loss	—	1,446	3,198
Effect of unwinding the discount related to advances made to CROs	—	—	355
Day-one gain on recognition of financial liabilities	—	—	212
Gain on derecognition of financial liabilities	—	—	192
Other financial income	84	306	130
Financial income	2,509	11,118	7,511
Financial gain (loss)	(1,052)	4,096	(20,364)

Financial liabilities - Disclosure of the main data and assumptions, Heights convertible loan notes (Details) - Heights convertible notes, tranche A € in Thousands	Dec. 31, 2023 EUR (€) € / shares shares	Aug. 24, 2023 EUR (€) € / shares shares
Disclosure of financial liabilities [line items]
Number of outstanding notes (in shares) \| shares	350	350
Original principal amount \| €	€ 35,000	€ 35,000
Fair value of convertible notes \| €	€ 27,456	€ 32,641
Interest rate \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.06	0.06
Conversion price per share (in euro per share) \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	23.77	23.77
Ordinary share price (in euro per share) \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	9.82	16.74
Held to maturity / voluntary conversion scenario probability \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.75	0.75
Initial price limit (in euro per share) \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	14.43	14.43
Early redemption amount (put event) \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	1.20	1.20
Volatility \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.50	0.50
Credit spread \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.20	0.20
Risk-free rate \| Monte Carlo model
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.023	0.029

Property, plant and equipment - Disclosure of reconciliation of property, plant and equipment (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	€ 1,592	€ 305	€ 493
Property, plant and equipment including right-of-use assets at end of period	878	1,592	305
ROU
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	1,270	212	394
Property, plant and equipment including right-of-use assets at end of period	501	1,270	212
BUILDINGS
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	1,359	148	371
Property, plant and equipment including right-of-use assets at end of period	509	1,359	148
EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	59	56	79
Property, plant and equipment including right-of-use assets at end of period	126	59	56
FURNITURE AND COMPUTER EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	175	101	44
Property, plant and equipment including right-of-use assets at end of period	242	175	101
GROSS VALUES
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	2,400	1,230	1,234
Acquisition	614	1,768	109
Disposal	(649)	(597)	(114)
Transfer
Property, plant and equipment including right-of-use assets at end of period	2,366	2,400	1,230
GROSS VALUES \| ROU
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	1,561	682	636
Acquisition	350	1,472	62
Disposal	(649)	(593)	(16)
Transfer
Property, plant and equipment including right-of-use assets at end of period	1,262	1,561	682
GROSS VALUES \| BUILDINGS
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	1,618	593	593
Acquisition	350	1,618
Disposal	(622)	(593)
Transfer
Property, plant and equipment including right-of-use assets at end of period	1,346	1,618	593
GROSS VALUES \| EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	436	402	447
Acquisition	103	39	23
Disposal	(27)	(3)	(67)
Transfer
Property, plant and equipment including right-of-use assets at end of period	513	436	402
GROSS VALUES \| FURNITURE AND COMPUTER EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	346	235	194
Acquisition	161	111	87
Disposal		(1)	(46)
Transfer
Property, plant and equipment including right-of-use assets at end of period	507	346	235
DEPRECIATION
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	(808)	(925)	(741)
Increase	(708)	(481)	(297)
Decrease	27	597	114
Property, plant and equipment including right-of-use assets at end of period	(1,488)	(808)	(925)
DEPRECIATION \| ROU
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	(290)	(470)	(243)
Increase	(498)	(414)	(244)
Decrease	27	593	16
Property, plant and equipment including right-of-use assets at end of period	(761)	(290)	(470)
DEPRECIATION \| BUILDINGS
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	(259)	(445)	(222)
Increase	(578)	(407)	(222)
Decrease	0	593	0
Property, plant and equipment including right-of-use assets at end of period	(837)	(259)	(445)
DEPRECIATION \| EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	(378)	(346)	(368)
Increase	(36)	(35)	(45)
Decrease	27	3	67
Property, plant and equipment including right-of-use assets at end of period	(387)	(378)	(346)
DEPRECIATION \| FURNITURE AND COMPUTER EQUIPMENT
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment including right-of-use assets at beginning of period	(171)	(134)	(151)
Increase	(94)	(38)	(30)
Decrease	0	1	46
Property, plant and equipment including right-of-use assets at end of period	€ (265)	€ (171)	€ (134)

Share-based payments - Disclosure of reconciliation of BCEs (Details) - shares							12 Months Ended	118 Months Ended
	May 14, 2018	Mar. 15, 2018	Nov. 20, 2017	Jan. 23, 2017	Nov. 07, 2016	Mar. 11, 2014	Dec. 31, 2023	Dec. 31, 2023
Total BCEs
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)								534,386
Number of instruments outstanding, beginning balance (in shares)							424,093
Number of instruments lapsed (in shares)							(37,500)
Number of instruments exercised (in shares)							(1,184)
Number of instruments outstanding, ending balance (in shares)							385,409	385,409
Number of instruments exercisable (in shares)							267,504	267,504
Maximum number of shares to be issued if all conditions are met (in shares)							385,409	385,409
BCE-2014-2
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)						2,750
Number of instruments outstanding, beginning balance (in shares)							1,000
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							(1,000)
Number of instruments outstanding, ending balance (in shares)							0	0
Number of instruments exercisable (in shares)							0	0
Maximum number of shares to be issued if all conditions are met (in shares)							0	0
BCE-2014-4
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)						984
Number of instruments outstanding, beginning balance (in shares)							184
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							(184)
Number of instruments outstanding, ending balance (in shares)							0	0
Number of instruments exercisable (in shares)							0	0
Maximum number of shares to be issued if all conditions are met (in shares)							0	0
BCE-2016-1
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)					84,000
Number of instruments outstanding, beginning balance (in shares)							22,495
Number of instruments lapsed (in shares)
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							22,495	22,495
Number of instruments exercisable (in shares)							22,495	22,495
Maximum number of shares to be issued if all conditions are met (in shares)							22,495	22,495
BCE-2017-1
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)				67,374
Number of instruments outstanding, beginning balance (in shares)							67,000
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							67,000	67,000
Number of instruments exercisable (in shares)							41,735	41,735
Maximum number of shares to be issued if all conditions are met (in shares)							67,000	67,000
BCE-2017-2
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)			150,000
Number of instruments outstanding, beginning balance (in shares)							150,000
Number of instruments lapsed (in shares)							(37,500)
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							112,500	112,500
Number of instruments exercisable (in shares)							112,500	112,500
Maximum number of shares to be issued if all conditions are met (in shares)							112,500	112,500
BCE-2017-4
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)			67,374
Number of instruments outstanding, beginning balance (in shares)							67,373
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							67,373	67,373
Number of instruments exercisable (in shares)							33,686	33,686
Maximum number of shares to be issued if all conditions are met (in shares)							67,373	67,373
BCE-2017-5
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)			67,374
Number of instruments outstanding, beginning balance (in shares)							64,374
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							64,374	64,374
Number of instruments exercisable (in shares)							30,686	30,686
Maximum number of shares to be issued if all conditions are met (in shares)							64,374	64,374
BCE-2018-1
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)		22,000
Number of instruments outstanding, beginning balance (in shares)							11,980
Number of instruments lapsed (in shares)
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							11,980	11,980
Number of instruments exercisable (in shares)							11,980	11,980
Maximum number of shares to be issued if all conditions are met (in shares)							11,980	11,980
BCE 2018-3
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)	33,687
Number of instruments outstanding, beginning balance (in shares)							16,844
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							16,844	16,844
Number of instruments exercisable (in shares)							0	0
Maximum number of shares to be issued if all conditions are met (in shares)							16,844	16,844
BCE-2018-4
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)	16,843
Number of instruments outstanding, beginning balance (in shares)							16,843
Number of instruments lapsed (in shares)							0
Number of instruments exercised (in shares)							0
Number of instruments outstanding, ending balance (in shares)							16,843	16,843
Number of instruments exercisable (in shares)							8,422	8,422
Maximum number of shares to be issued if all conditions are met (in shares)							16,843	16,843
BCE-2018-5
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments issued (in shares)	22,000
Number of instruments outstanding, beginning balance (in shares)							6,000
Number of instruments lapsed (in shares)
Number of instruments exercised (in shares)
Number of instruments outstanding, ending balance (in shares)							6,000	6,000
Number of instruments exercisable (in shares)							6,000	6,000
Maximum number of shares to be issued if all conditions are met (in shares)							6,000	6,000

Other receivables and other assets

12 Months Ended

Dec. 31, 2023

Trade and other receivables [abstract]

Other receivables and other assets

Other receivables and other assets break down as follows:


(amounts in thousands of euros)	AS OF DECEMBER 31, 2021	AS OF DECEMBER 31, 2022	AS OF DECEMBER 31, 2023
OTHER RECEIVABLES AND OTHER ASSETS
Prepaid expenses - non current	—	1,037	2,320
Total non-current other assets	—	1,037	2,320
Research tax credit ("CIR")	4,374	4,595	4,600
VAT receivables	3,961	3,467	14,439
Advance made to the Nice CHU	4,000	—	—
Advance payments for the acquisition of Prosynergia	1,725	—	—
Prepaid expenses	721	915	5,746
Credit notes	4	254	60
Total current other receivables and assets	14,784	9,231	24,845
Other receivables and other assets	14,784	10,268	27,164

Research tax credit (“CIR”)

The CIR is recognized as Other Operating Income (see note 4.9) in the year to which the eligible research expense relates. The Group

received the payments of the CIR for 2021 and 2022 tax years in the amount of respectively €4,204 thousand and €4,476 thousand

and expects to receive the CIR for 2023 tax year of €4,493 thousand in 2024.

VAT Receivables

Value-added tax (“VAT”) receivables relate primarily to the deductible VAT and VAT refunds claimed.

Their increase as of December 31, 2023 compared to December 31, 2022 is due to the increase in trade payables and accrued invoices

over the period (see Note 17.1).

Advance made to the Nice CHU

On January 20, 2021, the Group amended the research agreement entered with the University Hospital Center of Nice (or “Nice

CHU”) on September 25, 2020, which consisted in the conduct of a study to test whether ABX464 could prevent the development of

severe Covid-19 disease in the participants. The Group agreed to advance amount of €4,000 thousand to Nice CHU corresponding to

the expenses recharged by its third parties for the year ended December 31, 2021. An amount of €3,302 thousand was reimbursed in

August 2022. The remaining €698 thousand amount was settled by way of compensation with a payable due to the Nice CHU related

to the recharge of third-party services expenses.

Advance payment for the acquisition of Prosynergia

In the context of the acquisition of Prosynergia, the Group made an initial payment of the acquisition price of €325 thousand on

November 25, 2021.

On December 1, 2021, the Group signed a loan agreement with Prosynergia for €1,400 thousand. Prosynergia committed to reimburse

the loan at the end of the contract, on December 31, 2025. The purpose of the loan was to allow early repayment by Prosynergia of all

its existing indebtedness and was a suspensive condition for the acquisition of Prosynergia shares provided by the Share purchase

agreement entered with the shareholder of Prosynergia on November 15, 2021. For accounting purposes, this loan was considered as a

prepayment for the acquisition of the group of assets, which was repayable in cash only in the event the acquisition is not completed.

As of December 31, 2022, there was no more loan recognized following the merger of the Company and Prosynergia on December 12,

2022.

Prepaid expenses

Prepaid expenses as of December 31, 2021 include costs related to the acquisition of Prosynergia for €451 thousand. During the year

ended December 31, 2022, these costs were then included in the acquisition price of Prosynergia which was allocated to acquired

patents (see Notes 3.2 and 4.15).

Prepaid expenses as of December 31, 2022 include prepaid expenses related to CRO contracts for amount of €1,714 thousand (see

Note 9).

Prepaid expenses as of December 31, 2023 include prepaid expenses related to CRO contracts for an amount of €1,347 thousand (see

Note 9) and deferred transactions costs related to tranches B and C of the Kreos / Claret financings for an amount of €3,152 thousand

(most of which represents the issuance date fair value of the tranche A-B and C Kreos / Claret BSA, representing origination fees for

the future drawdowns of the tranches B and C of the Kreos / Claret Financing, See Note 15.1) and other expenses from various

suppliers amounting to €3,567 thousand.

Retirement benefit obligations (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of defined benefit plans [abstract]

Disclosure of main actuarial assumptions used to measure the retirement benefit obligations

The main actuarial assumptions used to measure the retirement benefit

obligations are as follows:


ACTUARIAL ASSUMPTIONS	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Retirement age	65 years for key management / 63 years for other employees	65 years for key management / 63 years for other employees	65 years for key management / 64 years for other employees
Collective agreement	Pharmaceutical industry	Pharmaceutical industry	Pharmaceutical industry
Discount Rate (IBoxx Corporates AA)	0.90%	3.65%	3.34%
Mortality rate table	INSEE 2016-2018	INSEE 2016-2018	INSEE 2016-2018
Salary increase rate	3.00% for key management / 2.55% for other employees	3.00% for key management / 2.55% for other employees	3.00%
Turnover rate	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old	Decreasing from 5.80% at 20 years-old to 0.05% from 55 years-old
Employee contribution rate	45%	45%	45%

Disclosure of changes in projected benefit obligation

Changes in the projected benefit obligation for the periods presented were as follows:


(amounts in thousands of euros)	RETIREMENT BENEFIT OBLIGATIONS
AS OF JANUARY 1, 2021	745
Service cost	166
Interest cost	4
Benefits paid	(53)
Actuarial gains and losses	(169)
AS OF DECEMBER 31, 2021	693
Service cost	143
Interest cost	8
Benefits paid
Actuarial gains and losses	(235)
AS OF DECEMBER 31, 2022	610
Service cost	109
Interest cost	23
Benefits paid
Actuarial gains and losses	(112)
AS OF DECEMBER 31, 2023	629

Off-balance sheet commitments given	12 Months Ended
Off-balance sheet commitments given	Dec. 31, 2023
Off-Balance Sheet Commitments [Abstract]
Off-balance sheet commitments given	Off-balance sheet commitments givenNote 25.1. Commitments under collaboration, research, service provision and licensing agreements granted by the Group Collaboration, research and development, and licensing agreements, and licensing options related to the “Modulation of RNA biogenesis” platform. •Exclusive licensing agreement with the CNRS, the University of Montpellier and the Institut Curie On December 4, 2008, the French National Centre for Scientific Research (CNRS), the University of Montpellier and the Institut Curie granted the Group four exclusive licenses. These licenses cover the use of their technology and products by the Group in the field of human and veterinary health relating to the use of synthetic products modifying mRNA splicing, for research, diagnosis, prevention and treatment of any possible indication. The licensing agreement includes low single-digit royalties based on future net sales to be paid by the Group. •Framework agreement for research collaboration to create a cooperative laboratory (ended December 31, 2021) On December 11, 2008, the Group, the CNRS (French National Centre for Scientific Research) and the University of Montpellier entered into a research collaboration agreement for a duration of two years in order to conduct a common research program in the fields of screening and development of anti-HIV and antiviral compounds, anti-cancer and anti- metastasis compounds and compounds targeting certain genetic diseases. The term and content of research programs have been changed by successive amendments in force until December 31, 2021. Each party retains ownership of its previously acquired intellectual property rights. The parties are co-owners of the research results. Since this agreement ended on December 31, 2021, a hosting agreement was signed with CNRS in 2022, it was successively renewed up until December 31, 2023 and December 31, 2024 so that the Group can continue its research program at the CNRS center for the years 2023 and 2024. •Collaboration agreement with the CNRS, the University of Montpellier, the Group and Evotec In support of the development of the cooperative laboratory, the CNRS, the University of Montpellier, the Group and Evotec International GmbH have entered into a collaboration agreement on the development of the “Modulation of RNA biogenesis” platform, effective October 19, 2018. The molecules generated in the framework of this collaboration are the property of the Group, the University of Montpellier and the CNRS under the same terms and conditions as the research collaboration agreement on the creation of the cooperative laboratory. The agreement ended on December 31, 2021. •Research collaboration contract with the CNRS, the University of Montpellier and the Institut Curie Concomitantly with the research collaboration framework contract relating to the creation of a cooperative laboratory the parties have signed a financial agreement defining the financial terms for the exploitation of patents. This contract was signed on 15 April 2009 for a duration of one year and was subsequently renewed up until March 31, 2022. In December 2022, Abivax and the Institut Curie concluded a new contract for a duration of one year, renewable by amendment, granting Abivax access to some of the Institute’s equipment and consumables. In December 2023, the contract was renewed for another year, under similar conditions. •Research and development contract with license option with the CNRS, the University of Montpellier and Theradiag The CNRS, the University of Montpellier, the Group and Theradiag have set up a collaborative project called CARENA, which has been in operation since February 8, 2013. Its purpose is to conduct joint research and development programs in the fields of obesity, HIV and HTLV-1, in connection with the funding obtained through the Bpifrance CARENA project. On February 18, 2015, Bpifrance accepted the reorganization of the “CARENA” project proposed by the Group, following the abandonment of the obesity project. At this time, Theradiag is no longer involved in the collaborative project. Under the terms of the collaborative project, the Group will have the exclusive and global exploitation rights to the proprietary results of the CNRS and to those of the University of Montpellier as well as a share of the common results of which the CNRS and the University of Montpellier are co-owners. Furthermore, Theradiag granted the Group an exclusive and global license option for exploitation of its own results as well as a share of the common results of which it will be a co-owner. This option may be exercised by the Group throughout the duration of the contract and within a period of two years after its expiration or cancellation. Exclusive licensing contract with “The Scripps Research Institute, University of Chicago and Brigham Young University” with the “Immune Stimulation” platform (ABX196 product) On 11 November 2006, The Scripps Research Institute (La Jolla, California, USA), in agreement with the University of Chicago (Chicago, Illinois, USA) and Brigham Young University (Provo, Utah, USA), granted the Group an exclusive license in the field of human and veterinary health on its technology and products relating to the use of iNKT agonists for research, diagnosis, prevention and treatment of all possible indications. In consideration for the licensing rights granted to it under the agreement, the Group must: •pay The Scripps Research Institute milestones at different stages of clinical and regulatory development of the first product (the milestones amount to $50 thousand at IND filing, paid in September 2019 and capitalized, $300 thousand at Phase 3 and $500 thousand at IND approval) and low single-digit royalties for vaccines, diagnostic tests and therapeutic products, according to the amount of net sales, and •give The Scripps Research Institute, University of Chicago and Brigham Young University an equitable interest in the Group (as of the date of these financial statements, these three academic institutions hold 0.41% of the Group’s undiluted capital). The contract shall be terminated at the expiry of the last licensed patent in force in the last country and/or ten years after the last marketing of the product, service or process derived from the know-how or the licensed equipment. Note 25.2. Commitments under BPI conditional advances Bpifrance CARENA contract As part of the development of therapeutic and diagnostic solutions targeting alternative splicing and RNA interference in the fields of virology (HIV-AIDS, HTLV-1) and metabolism (obesity), SPLICOS (absorbed by the Group on 31 October 2014) has entered into a Master Support Agreement with Bpifrance as well as a conditional advance contract in the name of the “CARENA” Strategic Industrial Innovation Project dated December 16, 2013. The Group, acting as project leader for the CARENA project, is associated as part of a consortium contract with Theradiag, a Group specializing in in vitro diagnostics and the development of theranostic tests for monitoring biotherapies, as well as at the CNRS and the University of Montpellier. The CARENA project aims to develop the anti-HIV-AIDS therapeutic program with the compound ABX464 up to the Phase 2b study, as well as a companion test set up by Theradiag simultaneously with the clinical development. Beyond the anti-HIV-AIDS program, the CARENA project should extend its pharmacological investigations to another retrovirus that could be combated by the same approach: HTLV-1. The Group is committed to reimbursing the received conditional advances up to €3,840 thousand. The Group will also have to pay an annuity of 50% of the proceeds from the sale of the intellectual property rights resulting from the project, as well as the sale of the prototypes, preproduction and models produced under the project; The sum due to BPI under this provision will be deducted from the repayment of the conditional advances. In addition, if the advance is repaid under the conditions outlined above, the Group will pay to Bpifrance, over a period of five consecutive years after the date on which the repayment schedule ends and provided that the Group has reached cumulative pre-tax revenue greater than or equal to €50 million, an amount equal to 1.20% of the annual revenue generated from the sale of the products developed as part of the project. This supplementary payment amount is capped at €6,800 thousand. The total period, including fixed payments and incentive payments, is limited to 15 years. Bpifrance RNP-VIR contract In pursuit of the CARENA project, focused on the clinical development of a drug molecule and demonstrating the validity of an innovative therapeutic approach targeting viral RNPs, the Group has entered into a Master Support Agreement with Bpifrance as well as a beneficiary agreement with conditional advance for the “RNP-VIR” structuring research and development project for competitiveness dated December 16, 2016. The RNP-VIR project will further the discovery of new molecules aimed at the treatment of multiple infectious diseases by the development of the antiviral technology platform. The Group, acting as project leader of the RNP-VIR project, is associated in a consortium contract with the CNRS and the University of Montpellier. The Group is committed to reimburse the received conditional advances up to €6,576 thousand. If applicable, the Group will also have to pay an annuity of 50% of the proceeds from the sale of the intellectual property rights resulting from the project, as well as the sale of the prototypes, preproduction and models produced under the project. The sum due to Bpifrance under this provision will be deducted from the last payment (and if needed from the previous payments). If the advance is repaid under the conditions outlined above, the Group will pay to Bpifrance, over a period of five consecutive years following the date on which the repayment schedule ends and provided that the Group has reached cumulative pre-tax revenue greater than or equal to €25 million, an amount equal to 3% of the annual revenue generated from the sale of products developed as part of the project. The supplementary payments amount is capped at €5,500 thousand. The total period, including fixed payments and incentive payments, is limited to 15 years. Bpifrance Ebola The Bpifrance and Occitanie Region joint support agreement granted on June 2, 2017 consists of conditional advances to the Group for a total amount of up to €390 thousand, based on the success of the program (respectively €130 thousand from the Languedoc Roussillon Midi Pyrénées Region and €260 thousand from Bpifrance). In September 2019, the Group decided to terminate this program, due to the existence of a vaccine in the process of being licensed for this indication as well as changes in the macroeconomic climate for public funding. The reimbursement of the conditional advance is spread until June 2024. Note 25.3. Pledge assets to Kreos, Claret and Heights As part of the KREOS 1 & 2 bonds, Kreos benefits from first-rate collateral on the Group’s principal tangible and intangible assets, including its commercial fund, intellectual property rights in its principal drug candidates, as well as a pledge of the Group’s bank accounts and claims. On August 21, 2023, the outstanding Kreos 1 & 2 bond loans were repaid in full, using the proceeds from the new Kreos / Claret Financing (see Note 3.3). The Kreos / Claret Financing provides for certain restrictive covenants (subject to customary exceptions) which include, among other things, restrictions on the incurrence of indebtedness, cross-default, the distribution of dividends and the grant of security interests. As security for the Kreos / Claret Financing, the lenders benefit from the grant of first-ranking collateral on The Group’s principal tangible and intangible assets, including pledges over The Group’s business (fonds de commerce) as a going concern and intellectual property rights in The Group's lead drug candidate, as well as pledges over The Group’s bank accounts and receivables. Such securities apply to all tranches of the Kreos / Claret Financing. The Heights Financing is a senior, unsecured financing. The terms and conditions of the Heights convertible notes include a standard negative pledge providing that any security granted in favor of other borrowed debt or debt instruments should also be granted in favor of the Heights convertible notes on an equal basis (with the exception of the securities issued pursuant to the Kreos / Claret Financing, as detailed above). Note 25.4. Other commitments related to research and partnership arrangements In the ordinary course of business, the Group regularly uses the services of subcontractors and enters into research and partnership arrangements with various contract research organizations, or CROs, and with public- sector partners or subcontractors, who conduct clinical trials and studies in relation to the drug candidates. At December 31, 2022, the Group’s commitments amounted to €194,731 thousand. The cost of services performed by CROs is recognized as an operating expense as incurred. At December 31, 2023, the Group’s commitments amounted to €201,777 thousand. The cost of services performed by CROs is recognized as an operating expense as incurred. Note 25.5. Leases The lease for the Group’s corporate headquarters in Paris, France at 5 Rue de la Baume, 75008 Paris ended in August 2022. A new lease for premises at 7-11 Boulevard Haussmann, 75009 Paris started in July 2022 and will end on June 30, 2024. In November 2023, the Subsidiary entered a lease contract for its new Boston offices. It has a two-year duration, with an option to renew the contract for an additional period of two years. Per Management, the renewal option is not reasonably certain due to the forecasted development of the Subsidiary, which may lead it to relocate at the end of the initial term.

Off-balance sheet commitments received and contingent assets	12 Months Ended
	Dec. 31, 2023
Off-Balance Sheet Commitments [Abstract]
Off-balance sheet commitments received and contingent assets	Off-balance sheet commitments received and contingent assets The maximum amounts receivable by the Group after December 31, 2023 under the “RNP-VIR” and “CARENA” and innovation agreements entered into with Bpifrance, subject to the provision of evidence to support the forecast expenses and the achievement of scientific milestones, are €3,255 thousand and €1,853 thousand, respectively. As part of the Kreos / Claret Financing agreement, the Group has received loan commitments from Kreos and Claret for the tranches B and C, of €25,000 thousand in aggregate principal amount each (subject to the conditions set forth in Note 15.1.). The limit dates for the drawdowns are March 31, 2024 and July 31, 2024 respectively. As part of the Heights Financing agreement, the Group has received a loan commitment from Heights for the tranche B, of up to €40,000 thousand in aggregate principal amount (subject to the conditions set forth in Note 15.2.). The limit date for the complete drawdown is August 24, 2024.

Goodwill and impairment test (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of information for cash-generating units [line items]
Goodwill	€ 18,419	€ 18,419	€ 32,005
Discount rate (WACC)	15.00%	14.00%	13.50%
Impairment loss recognised in profit or loss, intangible assets and goodwill	€ 0	€ 13,632	€ 0
Splicos SAS
Disclosure of information for cash-generating units [line items]
Goodwill			18,419
Wittycel SAS
Disclosure of information for cash-generating units [line items]
Goodwill			13,586
Impairment loss recognised in profit or loss, intangible assets and goodwill		13,632
Impairment loss recognised in profit or loss, goodwill		13,586
Impairment loss recognised in profit or loss, other intangible assets	€ 0	45	€ 0
Intangible assets with indefinite useful life		€ 0
Increase in discount rate, percentage points			3.7
Decrease in revenue, percentage			22.00%
Decrease in POS per share, percentage			10.00%

Segment information (Details)	12 Months Ended
Segment information (Details)	Dec. 31, 2023 segment
Disclosure of geographical areas [line items]
Number of operating segments	1
United States \| Top of range
Disclosure of geographical areas [line items]
Contribution to Group's assets, percentage	5.00%
Contribution to Group's liabilities, percentage	5.00%
Contribution to Group's net profits (losses), percentage	5.00%

Significant events for the years ended December 31, 2021, 2022 and 2023 and subsequent events - For the year ended 2022 (Details) € / shares in Units, € in Thousands, $ in Millions									1 Months Ended	6 Months Ended	8 Months Ended	12 Months Ended			121 Months Ended
	Oct. 24, 2023 EUR (€) € / shares shares	Oct. 24, 2023 USD ($) shares	Feb. 22, 2023 € / shares shares	Sep. 07, 2022 € / shares shares	Sep. 02, 2022 EUR (€) transaction € / shares shares	Dec. 01, 2021 EUR (€)	Jul. 30, 2021 € / shares shares	Jul. 27, 2021 € / shares shares	Aug. 31, 2022 EUR (€)	Jun. 30, 2023 EUR (€)	Dec. 12, 2022	Dec. 31, 2023 EUR (€) € / shares shares	Dec. 31, 2022 EUR (€) € / shares shares	Dec. 31, 2021 EUR (€) € / shares shares	Dec. 31, 2023 EUR (€) € / shares	May 24, 2023 € / shares	Apr. 01, 2022 EUR (€)	Nov. 25, 2021 EUR (€)
Disclosure of detailed information about borrowings [line items]
Advances and loans made to (reimbursed from) hospitals												€ 0	€ (3,302)	€ 4,000
Capital increases	€ 223,300	$ 235.8										€ 353,377	€ 46,231	€ 69,683	€ 557,200
Capital increase from issuance of ordinary shares (in shares) \| shares	20,325,500	20,325,500	20,000,000	5,530,000			1,964,031	1,964,031				40,325,500	5,530,000	1,964,031
Par value per share (in euro per share) \| € / shares	€ 0.01		€ 0.01	€ 0.01				€ 0.01				€ 0.01	€ 0.01	€ 0.01	€ 0.01	€ 0.01
Equity issuance, subscripion price per share (in euro per share) \| € / shares			€ 6.50	€ 8.36			€ 30.55	€ 30.55
Net proceeds from sale of royalty certificate					€ 2,931							€ 0	€ 2,931	€ 0	€ 2,900
Royalty certificate, percentage of future sales					2.00%
Royalty certificate, maximum amount					€ 172,000
Share issue related cost												28,111	3,280	4,090
Cash advances and loans made to CRO										€ 1,620		1,620	12,187	0
Advances related to CRO contracts												12,172	10,471	0	€ 12,172
Share premium
Disclosure of detailed information about borrowings [line items]
Share issue related cost												28,111	3,280	4,090
€49.2 million cross-over financing, september 2022
Disclosure of detailed information about borrowings [line items]
Financial agreement, amount					€ 49,200
Financial agreement, number of transactions \| transaction					2
Capital increases					€ 46,200
Capital increase from issuance of ordinary shares (in shares) \| shares					5,530,000
Par value per share (in euro per share) \| € / shares					€ 0.01
Equity issuance, percentage of current share capital			89.60%		33.00%
Equity issuance, subscripion price per share (in euro per share) \| € / shares					€ 8.36
Net proceeds from sale of royalty certificate					€ 2,900
Royalty certificate, percentage of future sales					2.00%
Royalty certificate, maximum amount					€ 172,000
€49.2 million cross-over financing, september 2022 \| Share premium
Disclosure of detailed information about borrowings [line items]
Share issue related cost					€ 3,300
Research agreement with University Hospital Center of Nice
Disclosure of detailed information about borrowings [line items]
Advances and loans made to (reimbursed from) hospitals									€ (3,302)					4,000
Other expenses													698
AGA 2021
Disclosure of detailed information about borrowings [line items]
Compensation expenses													1,026	(828)
Share-based compensation expense, social taxes													205
Wittycel SAS
Disclosure of detailed information about borrowings [line items]
Impairment loss recognised in profit or loss, goodwill													13,586
Impairment loss recognised in profit or loss, other intangible assets												€ 0	45	€ 0
Intangible assets with indefinite useful life													€ 0
Prosynergia
Disclosure of detailed information about borrowings [line items]
Loan granted						€ 1,400
Prosynergia
Disclosure of detailed information about borrowings [line items]
Cash prepayment made in 2021																	€ 325	€ 325
Cash payment made in 2022																	2,925
Earn-out, maximum amount																	4,000
Loan granted to Prosynergia in 2021						€ 1,400											€ 1,400
Prosynergia
Disclosure of detailed information about borrowings [line items]
Proportion of ownership interest in subsidiary											100.00%

Operating expenses - Disclosure of general and administrative expenses (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of attribution of expenses by nature to their function [line items]
Operating expenses	€ 131,997	€ 69,419	€ 53,361
General and administrative expense
Disclosure of attribution of expenses by nature to their function [line items]
Personnel costs	13,104	1,403	2,320
Consulting and professional fees	6,393	2,624	2,026
Other expenses	2,893	3,466	1,233
Operating expenses	€ 22,390	€ 7,492	€ 5,580

Financial liabilities - Disclosure of main data and assumptions used for the measurement of earn-out liability (Details) - Prosynergia earn-out liability € in Thousands	Dec. 31, 2022 EUR (€) € / shares yr	Apr. 01, 2022 EUR (€) € / shares yr
Disclosure of financial liabilities [line items]
Fair value of earn-out liability	€ 0	€ (1,446)
Option pricing model \| Risk-free rate
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.023	(0.003)
Option pricing model \| Market capitalization
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	135,952	403,118
Option pricing model \| Ordinary share price (in euro per share)
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities \| € / shares	6.18	24.15
Option pricing model \| Time to maturity
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities \| yr	0.25	1
Option pricing model \| Volatility
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0.44	0.61
Option pricing model \| Dividend
Disclosure of financial liabilities [line items]
Significant unobservable input, liabilities	0	0

Financial liabilities - Disclosure of the main data and assumptions, Kreos / Claret BSA (Details) € in Thousands		12 Months Ended
	Aug. 22, 2023 EUR (€) € / shares shares	Dec. 31, 2023 EUR (€) € / shares scenario shares	Nov. 02, 2023 EUR (€) € / shares shares
Kreos A & B BSA \| Option pricing model \| Exercise price per share (in euro per share)
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	18.67	18.67
Kreos A & B BSA \| Option pricing model \| Ordinary share price (in euro per share)
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	17.10	9.82
Kreos A & B BSA \| Option pricing model \| 7-year expiry scenario probability
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	0.50	0.95
Kreos A & B BSA \| Option pricing model \| Volatility, expiry
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	0.719	0.595
Kreos A & B BSA \| Option pricing model \| Volatility, tender offer
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	0.652	0.649
Kreos A & B BSA \| Option pricing model \| Dividend
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	0	0
Kreos A & B BSA \| Option pricing model \| Risk-free rate
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	0.0300	0.0230
Kreos C BSA \| Option pricing model \| Exercise price per share (in euro per share)
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		9.86	9.86
Kreos C BSA \| Option pricing model \| Ordinary share price (in euro per share)
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		9.82	8.89
Kreos C BSA \| Option pricing model \| 7-year expiry scenario probability
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.95	0.95
Kreos C BSA \| Option pricing model \| Probability of Drawdown of Tranche C credit facility
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.30	0.30
Kreos C BSA \| Option pricing model \| Volatility, expiry
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.674	0.673
Kreos C BSA \| Option pricing model \| Volatility, tender offer
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.649	0.643
Kreos C BSA \| Option pricing model \| Dividend
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0	0
Kreos C BSA \| Option pricing model \| Risk-free rate
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.023	0.030
Kreos A & B BSA
Disclosure Of Warrants Arrangements [Line Items]
Number of probability-weighted scenarios \| scenario		2
Expiry scenario period, other equity instruments granted	7 years
Number of outstanding warrants (in shares) \| shares	214,198	214,198
Fair value of other equity instruments \| €	€ 2,092	€ 920
Kreos C BSA
Disclosure Of Warrants Arrangements [Line Items]
Number of outstanding warrants (in shares) \| shares		405,832	405,832
Number of outstanding warrants subject to non-market performance condition (in shares) \| shares		202,915	202,915
Fair value of other equity instruments \| €		€ 1,659	€ 1,493

Payables and other current liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Trade and other current payables [abstract]

Disclosure of breakdown of trade and other payables

Trade payables and other current liabilities break down as follows:


(amounts in thousands of euros)
TRADE PAYABLES AND OTHER CURRENT LIABILITIES	AS OF DECEMBER 31, 2021	AS OF DECEMBER 31, 2022	AS OF DECEMBER 31, 2023
Trade payables	12,890	8,216	21,953
Accrued invoices	5,661	7,250	25,269
Other	7	9	(1)
Trade payables and other current liabilities	18,558	15,475	47,221

Disclosure of tax and employee-related payables

Tax and employee-related payables are presented below:


(amounts in thousands of euros)
TAX AND EMPLOYEE-RELATED PAYABLES	AS OF DECEMBER 31, 2021	AS OF DECEMBER 31, 2022	AS OF DECEMBER 31, 2023
Employee-related payables	1,180	1,348	3,694
Social security and other	777	840	2,251
Other tax and related payments	243	112	127
Tax and employee-related payables	2,200	2,300	6,073

Income (loss) per share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings per share [abstract]

Schedule of earnings per share


(amounts in thousands of euros, except share data)
BASIC AND DILUTED LOSS PER SHARE	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Weighted average number of outstanding shares	15,455,991	19,092,442	43,066,012
Net loss for the period	(42,452)	(60,740)	(147,740)
Basic and diluted loss per share (€/share)	(2.75)	(3.18)	(3.43)

Operating expenses - Disclosure of sales and marketing expenses (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of attribution of expenses by nature to their function [line items]
Operating expenses	€ 131,997	€ 69,419	€ 53,361
Sales and marketing expenses
Disclosure of attribution of expenses by nature to their function [line items]
Personnel costs	1,710	0	0
Consulting and professional fees	4,012	0	0
Other expenses	709	0	0
Operating expenses	€ 6,431	€ 0	€ 0

Shareholders’ equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [abstract]

Disclosure of reconciliation of other equity instruments



	NUMBER OF BSAs OUTSTANDING	MAXIMUM NUMBER OF SHARES TO BE ISSUED	NUMBER OF BSAs EXERCISED	NUMBER OF BSAs LAPSED	NUMBER OF BSAs OUTSTANDING	MAXIMUM NUMBER OF SHARES TO BE ISSUED

			FOR THE YEAR ENDED
	AS OF DECEMBER 31, 2021		DECEMBER 31, 2022		AS OF DECEMBER 31, 2022
BSAs granted under the Equity line agrement ......................................	300,000	300,000	—	(300,000)	—	—

The following tables summarize the data relating to BCEs as well as the assumptions used for the measurement thereof in accordance

with IFRS 2 – Share-based Payment:


GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BCEs	NUMBER OF EXERCISED BCEs	NUMBER OF BCEs OUTSTANDI NG	NUMBER OF BCEs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITION S ARE MET
GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BCE-2014-2	2,750	1,000	—	(1,000)	—	—	—
2014-03-11	BCE-2014-4	984	184	—	(184)	—	—	—
2016-11-07	BCE-2016-1	84,000	22,495		—	22,495	22,495	22,495
2017-01-23	BCE-2017-1	67,374	67,000	—	—	67,000	41,735	67,000
2017-11-20	BCE-2017-2	150,000	150,000	(37,500)	—	112,500	112,500	112,500
2017-11-20	BCE-2017-4	67,374	67,373	—	—	67,373	33,686	67,373
2017-11-20	BCE-2017-5	67,374	64,374	—	—	64,374	30,686	64,374
2018-03-15	BCE-2018-1	22,000	11,980		—	11,980	11,980	11,980
2018-05-14	BCE 2018-3	33,687	16,844	—	—	16,844	—	16,844
2018-05-14	BCE-2018-4	16,843	16,843	0	—	16,843	8,422	16,843
2018-05-14	BCE-2018-5	22,000	6,000			6,000	6,000	6,000
	Total BCEs	534,386	424,093	(37,500)	(1,184)	385,409	267,504	385,409

The following tables summarize the data relating to BSAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BSAs	NUMBER OF EXERCISED BSAs	NUMBER OF BSAs OUTSTANDI NG	NUMBER OF BSAs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITIONS ARE MET
GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BSA-2014-3	1,172	492	—	(492)	—	—	—
2015-12-04	BSA-2015-11	96,924	96,924	—	—	96,924	96,924	96,924
2015-12-04	BSA-2015-12	82,000	16,400	—	—	16,400	16,400	16,400
2017-09-18	BSA-2017-1	16,400	16,400	—	—	16,400	16,400	16,400
2018-01-22	BSA-2018-1	49,200	16,400	—	—	16,400	16,400	16,400
2014-03-11	BSA-2014-4	1,315	842	—	—	842	842	84,160
2014-03-11	BSA-2014-5	787	459	—	(230)	230	230	22,950
	Total BSAs	247,798	147,917	—	(722)	147,196	147,195	253,234

The following tables summarize the data relating to AGAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	NUMBER OF AGAs OUTSTANDING
GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	AS OF DECEMBER 31, 2023
2023-07-11	AGA-2023-1	1,382,796	—	—	—	1,382,796
2023-07-11	AGA-2023-2	100,000	—	—	—	100,000
2023-09-28	AGA-2023-3	731,500	—	—	—	731,500
2023-09-28	AGA-2023-4	254,250	—	—	—	254,250
2023-12-01	AGA-2023-5	132,750	—	—	—	132,750
	Total AGAs	2,601,296	—	—	—	2,601,296

Financial gain (loss) - Disclosure of net financial income (loss) (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financial Income (Loss) [Abstract]
Interest on Kreos 1 & 2 straight bond loans	€ (760)	€ (3,737)	€ (2,344)
Interest on convertible loan notes	(3,935)	(2,641)	(1,064)
Interest on conditional advances	(176)	(196)	(145)
Interest on royalty certificates	(8,942)	(356)	0
Interest on lease liabilities	(13)	(10)	(5)
Increase in derivatives fair value	(3,046)	0	0
Loss on derecognition of financial liabilities	(3,431)	0	0
Transaction costs	(1,924)	0	0
Foreign exchange losses	(5,573)	0	0
Other	(73)	(83)	(2)
Financial expenses	(27,875)	(7,022)	(3,561)
Interest income	2,418	0	0
Decrease/(increase) in derivatives fair value	1,006	9,366	2,425
Decrease/(increase) in other liabilities at fair value through profit and loss	3,198	1,446	0
Effect of unwinding the discount related to advances made to CROs	355	0	0
Day-one gain on recognition of financial liabilities	212	0	0
Gain on derecognition of financial liabilities	192	0	0
Other financial income	130	306	84
Financial income	7,511	11,118	2,509
Financial gain (loss)	€ (20,364)	€ 4,096	€ (1,052)

Financial liabilities - Disclosure of remaining contractual maturities of financial liabilities (Details) - EUR (€) € in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances	€ 6,771	€ 6,783	€ 6,770
Royalty certificates	12,229	3,287	0
Royalty certificates, undiscounted cash flows	0	0
Lease liabilities	540	1,384	214	€ 400
Gross lease liabilities	575	1,403	220
Derivative financial liabilities	2,579	566	9,932	5,196
Derivative financial liabilities, undiscounted cash flows	2,579	566	9,932
Total financial liabilities	77,045	49,797	61,585
Financial liabilities, undiscounted cash flows	81,500	59,053	80,098
LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Royalty certificates, undiscounted cash flows	0	0
Gross lease liabilities	406	558	175
Derivative financial liabilities, undiscounted cash flows	2,579	142	0
Financial liabilities, undiscounted cash flows	20,747	16,223	14,743
FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Royalty certificates, undiscounted cash flows	0	0
Gross lease liabilities	162	557	14
Derivative financial liabilities, undiscounted cash flows	0	0	0
Financial liabilities, undiscounted cash flows	15,192	9,905	13,179
FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Royalty certificates, undiscounted cash flows	0	0
Gross lease liabilities	7	289	31
Derivative financial liabilities, undiscounted cash flows	0	424	5,929
Financial liabilities, undiscounted cash flows	45,561	32,925	48,173
LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Royalty certificates, undiscounted cash flows	0	0
Gross lease liabilities	0	0	0
Derivative financial liabilities, undiscounted cash flows	0	0	4,003
Financial liabilities, undiscounted cash flows	0	0	4,003
Kreos 1 & 2 bond loans
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings		12,982	21,110
Borrowings, undiscounted cash flows		14,098	25,960
Kreos 1 & 2 bond loans \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows		9,034	11,862
Kreos 1 & 2 bond loans \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows		5,065	9,034
Kreos 1 & 2 bond loans \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows		0	5,065
Kreos 1 & 2 bond loans \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows		0	0
Oceane conversion option
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes		19,957	18,816
Convertible loans notes, undiscounted cash flows		31,000	31,750
Derivative financial liabilities	0	142	5,929	0
Oceane conversion option \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows		1,500	1,500
Oceane conversion option \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows		1,500	1,500
Oceane conversion option \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows		28,000	28,750
Oceane conversion option \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows		0	0
Heights convertible notes
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes	29,605
Convertible loans notes, undiscounted cash flows	36,750
Heights convertible notes \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	10,522
Heights convertible notes \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	9,997
Heights convertible notes \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	16,231
Heights convertible notes \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	0
Kreos / Claret convertible notes (OCABSA)
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes	21,643
Convertible loans notes, undiscounted cash flows	30,903
Derivative financial liabilities	2,579	0	0	€ 0
Kreos / Claret convertible notes (OCABSA) \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	2,250
Kreos / Claret convertible notes (OCABSA) \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	2,250
Kreos / Claret convertible notes (OCABSA) \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	26,403
Kreos / Claret convertible notes (OCABSA) \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Convertible loans notes, undiscounted cash flows	0
PGE
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings	3,678	4,838	4,742
Borrowings, undiscounted cash flows	3,880	5,173	5,227
PGE \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows	1,293	1,293	54
PGE \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows	1,293	1,293	1,293
PGE \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows	1,293	2,586	3,880
PGE \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Borrowings, undiscounted cash flows	0	0	0
BPI
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances	6,771	6,783	6,770
Conditional advances, undiscounted cash flows	6,813	6,813	7,008
BPI \| LESS THAN 1 YEAR
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances, undiscounted cash flows	3,697	3,697	1,152
BPI \| FROM 1 TO 2 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances, undiscounted cash flows	1,490	1,490	1,338
BPI \| FROM 2 TO 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances, undiscounted cash flows	1,626	1,626	4,518
BPI \| LONGER THAN 5 YEARS
Disclosure of maturity analysis for derivative financial liabilities [line items]
Conditional advances, undiscounted cash flows	€ 0	€ 0	€ 0

Off-balance sheet commitments given (Details) € in Thousands, $ in Thousands					1 Months Ended	12 Months Ended
	Dec. 16, 2016 EUR (€)	Dec. 16, 2013 EUR (€)	Feb. 08, 2013	Nov. 11, 2006 USD ($) academic_institution	Nov. 30, 2023	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 EUR (€)	Jun. 02, 2017 EUR (€)	Apr. 15, 2009	Dec. 11, 2008	Dec. 04, 2008 license
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Capital commitments						€ 201,777	€ 194,731
CARENA conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Maximum drawdown capacity		€ 3,840
Annual percentage of proceeds from sale of intellectual property right		50.00%
Annual revenue from sale of products developed, period		5 years
Percentage of annual revenue from sale of products developed		1.20%
RNP-VIR conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Maximum drawdown capacity	€ 6,300
Annual percentage of proceeds from sale of intellectual property right	50.00%
Annual revenue from sale of products developed, period	5 years
Percentage of annual revenue from sale of products developed	3.00%
Maximum drawdown capacity including interest	€ 6,576
Ebola conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Maximum drawdown capacity								€ 390
Ebola conditional advance, BPI Languedoc-Roussillon
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Maximum drawdown capacity								130
Ebola conditional advance, BPI France
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Maximum drawdown capacity								€ 260
Lease facilities, Boston
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Lease, duration period					2 years
Lease, extension period					2 years
Maximum \| CARENA conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Annual revenue from sale of products developed		€ 6,800
Repayment period		15 years
Maximum \| RNP-VIR conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Annual revenue from sale of products developed	€ 5,500
Repayment period	15 years
Minimum \| CARENA conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Pre-tax revenue threshold		€ 50,000
Minimum \| RNP-VIR conditional advance
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Pre-tax revenue threshold	€ 25,000
The Scripps Research Institute, University of Chicago and Brigham Young University
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Proportion of ownership interests held by non-controlling interests						0.41%
Exclusive licensing agreement with CNRS, University of Montpellier and Institut Curie
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Number of exclusive licenses \| license											4
Research and collaboration agreement with CNRS and University of Montpellier
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Agreement, period										2 years
Research and collaboration agreement with CNRS, University of Montpellier and Institut Curie
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Agreement, period						1 year	1 year		1 year
Research and development contract with license option with CNRS, University of Montpellier and Theradiag
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Agreement, license option period			2 years
Exclusive licensing contract with the Scripps Research Institute, University of Chicago and Brigham Young University
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Potential development milestone payment, IND filing \| $				$ 50
Potential development milestone payment, phase 3 \| $				300
Potential development milestone payment, IND approval \| $				$ 500
Number of academic institutions \| academic_institution				3
Exclusive licensing contract with the Scripps Research Institute, University of Chicago and Brigham Young University \| Maximum
Disclosure Of Off-Balance Sheet Commitments [Line Items]
Agreement, period after last marketing of product				10 years

Financial liabilities - Disclosure of the main data and assumptions, Kreos BSA (Details) € in Thousands	May 24, 2023 EUR (€) € / shares yr shares	Dec. 31, 2022 EUR (€) € / shares yr shares	Dec. 31, 2021 EUR (€) € / shares yr shares	Jul. 24, 2018 shares
Kreos A BSA
Disclosure Of Warrants Arrangements [Line Items]
Number of outstanding warrants (in shares) \| shares	110,957	110,957	110,957	110,957
Fair value of other equity instruments \| €	€ 1,261	€ 275	€ 2,478
Kreos A BSA \| Exercise price per share (in euro per share) \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	7.21	7.21	7.21
Kreos A BSA \| Ordinary share price (in euro per share) \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	18.57	6.18	28.55
Kreos A BSA \| Residual maturity \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities \| yr	0	5.6	6.6
Kreos A BSA \| Volatility \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.4401	0.4665
Kreos A BSA \| Dividend \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0	0
Kreos A BSA \| Risk-free rate \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.0298	0.0013
Kreos B BSA
Disclosure Of Warrants Arrangements [Line Items]
Number of outstanding warrants (in shares) \| shares	74,766	74,766	74,766	74,766
Fair value of other equity instruments \| €	€ 589	€ 149	€ 1,525
Kreos B BSA \| Exercise price per share (in euro per share) \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	10.70	10.70	10.70
Kreos B BSA \| Ordinary share price (in euro per share) \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities	18.57	6.18	28.55
Kreos B BSA \| Residual maturity \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities \| yr	0	6.4	7.4
Kreos B BSA \| Volatility \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.4401	0.4665
Kreos B BSA \| Dividend \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0	0
Kreos B BSA \| Risk-free rate \| Option pricing model
Disclosure Of Warrants Arrangements [Line Items]
Significant unobservable input, liabilities		0.0296	0.0013

Financial liabilities - Kreos 2 (Details) € in Thousands			12 Months Ended
Financial liabilities - Kreos 2 (Details) € in Thousands	Aug. 24, 2023 EUR (€)	Aug. 21, 2023 EUR (€)	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)	Oct. 13, 2020 EUR (€) tranche installment	Jul. 24, 2018 installment
Disclosure of detailed information about borrowings [line items]
Borrowings, number of monthly installments \| installment						36	54
Repayments of convertible loan notes	€ 33,000		€ 27,188	€ 0	€ 0
Kreos 2
Disclosure of detailed information about borrowings [line items]
Notional amount						€ 15,000
Borrowings, number of tranches \| tranche						2
Borrowings, additional tranche mount						€ 5,000
Borrowings, interest rate for following installments						9.75%
Borrowings, exit fee percentage						4.00%
Borrowings, notice period			30 days
Borrowings, exit fee percentage if prepayment between 18th and 30th installments						2.00%
Borrowings, exit fee percentage if prepayment after 30th installment						4.00%
Borrowings, annual discount rate						4.00%
Kreos 2 \| Euribor
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate for first 12 installments						8.00%
Kreos 2, tranche A
Disclosure of detailed information about borrowings [line items]
Notional amount						€ 10,000
Borrowings, exit fee amount						400
Kreos 2, tranche B
Disclosure of detailed information about borrowings [line items]
Notional amount						5,000
Borrowings, exit fee amount						€ 200
Kreos 1, convertible bond loans, tranche B
Disclosure of detailed information about borrowings [line items]
Repayments of convertible loan notes	€ 8,000	€ 7,661

Financial gain (loss)

12 Months Ended

Dec. 31, 2023

Financial Income (Loss) [Abstract]

Financial gain (loss)

The financial loss breaks down as follows:


(amounts in thousands of euros)
FINANCIAL GAIN (LOSS)	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
Interest on Kreos 1 & 2 straight bond loans	(2,344)	(3,737)	(760)
Interest on convertible loan notes	(1,064)	(2,641)	(3,935)
Interest on conditional advances	(145)	(196)	(176)
Interest on royalty certificates	—	(356)	(8,942)
Interest on lease liabilities	(5)	(10)	(13)
Increase in derivatives fair value	—	—	(3,046)
Loss on derecognition of financial liabilities	—	—	(3,431)
Transaction costs	—	—	(1,924)
Foreign exchange losses	—	—	(5,573)
Other	(2)	(83)	(73)
Financial expenses	(3,561)	(7,022)	(27,875)
Interest income	—	—	2,418
Decrease/(increase) in derivatives fair value	2,425	9,366	1,006
Decrease/(increase) in other liabilities at fair value through profit and loss	—	1,446	3,198
Effect of unwinding the discount related to advances made to CROs	—	—	355
Day-one gain on recognition of financial liabilities	—	—	212
Gain on derecognition of financial liabilities	—	—	192
Other financial income	84	306	130
Financial income	2,509	11,118	7,511
Financial gain (loss)	(1,052)	4,096	(20,364)

Increases and decreases in the fair value of derivatives are detailed in Notes 15.1, 15.3 and 15.12.

Increases and decreases in other liabilities at FVTPL relate to the Prosynergia earn-out liability for the year ended December 31, 2022

(see Note 15.9) and the Heights notes for the year ended December 31, 2023 (see Note 15.2).

Transaction costs for the year ended December 31, 2023 mainly relate to Heights notes.

Gains and losses on the recognition and derecognition of financial liabilities are set forth in Notes 15.2. to 15.5.

Foreign exchange losses for the year ended December 31, 2023 mainly relate to the translation of cash and cash equivalents held in

U.S. dollars into the Group's presentation currency as of December 31, 2023 (see Note 11), resulting in a loss of €3,196 thousand, and

to a €1,488 thousand loss resulting from foreign exchange operations.

Operating expenses - Disclosure of research and development expenses (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of attribution of expenses by nature to their function [line items]
Operating expenses	€ 131,997	€ 69,419	€ 53,361
Research and development expenses
Disclosure of attribution of expenses by nature to their function [line items]
Sub-contracting, studies and research	85,726	38,858	36,362
Personnel costs	8,048	3,072	5,179
Consulting and professional fees	6,561	4,246	4,016
Intellectual property fees	1,645	1,187	1,325
Other expenses	1,196	931	899
Operating expenses	€ 103,176	€ 48,295	€ 47,781

Financial liabilities - Disclosure of conditional advances (Details) - EUR (€) € in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about borrowings [line items]
Conditional advances	€ 6,771	€ 6,783	€ 6,770
RNP VIR – Bpifrance
Disclosure of detailed information about borrowings [line items]
Conditional advances	4,232	4,171	4,103
CARENA – Bpifrance
Disclosure of detailed information about borrowings [line items]
Conditional advances	2,485	2,454	2,423
EBOLA – Bpifrance
Disclosure of detailed information about borrowings [line items]
Conditional advances	55	158	244
COVID-19 – Bpifrance
Disclosure of detailed information about borrowings [line items]
Conditional advances	€ 0	€ 0	€ 0

Other financial assets (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of financial assets [abstract]

Disclosure of other financial assets

Other financial assets break down as follows:


(amounts in thousands of euros)	AS OF DECEMBER 31, 2021	AS OF DECEMBER 31, 2022	AS OF DECEMBER 31, 2023
OTHER FINANCIAL ASSETS
Advances related to CRO contracts	—	10,471	12,172
Deposits	1,342	1,238	574
Other	—	—	124
Total other non-current financial assets	1,342	11,708	12,870
Other investments	—	—	9,050
Deposits	—	—	136
Total other current financial assets	—	—	9,186
Other financial assets	1,342	11,708	22,055

The Group (Details) - EUR (€) € in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Corporate information and statement of IFRS compliance [abstract]
Equity	€ 196,010	€ 7,189	€ 25,934	€ 1,733

- Definition

The amount of residual interest in the assets of the entity after deducting all its liabilities.

+ References + Details

Accounting principles

12 Months Ended

Dec. 31, 2023

Accounting Principles [Abstract]

Accounting principles

Accounting principles Note 4.1. Goodwill

Following initial recognition, goodwill is stated at cost less any accumulated impairment losses (see Note 4.4).

In respect of business combinations prior to January 1, 2020, in accordance with IFRS 1 exemption, goodwill is included on the basis

of its deemed cost, which represents the amount recorded under the prior basis of accounting, French GAAP, (“Previous GAAP”).

Note 4.2. Intangible assets

Pursuant to IAS 38—Intangible Assets, intangible assets acquired are recognized as assets on the statements of financial position at

their acquisition cost.

Licenses

Payments for separately acquired research and development are capitalized within “Other intangible assets” provided that they meet

the definition of an intangible asset: a resource that is (i) controlled by the Group, (ii) expected to provide future economic benefits for

the Group and (iii) identifiable (i.e., it is either separable or arises from contractual or legal rights). In accordance with paragraph 25 of

IAS 38—Intangible Assets, the recognition criterion relating to the likelihood of future economic benefits generated by the intangible

asset, is presumed to be achieved for research and development activities when they are acquired separately. In this context, amounts

paid to third parties in the form of initial payments or milestone payments relating to pharmaceutical specialties that have not yet

obtained a marketing authorization are recognized as intangible assets. These rights will be amortized on a straight-line basis, after

obtaining the marketing authorization, over their useful life. Unamortized rights (before marketing authorization) are subject to

impairment tests in accordance with the method defined in Note 4.4.

Research and development costs

Pursuant to IAS 38 – Intangible Assets, research costs are expensed in the period during which they are incurred. Development costs

are only recognized as intangible assets if the following criteria are met:

•it is technically feasible to complete the development of the project;

•it is the Group’s intention to complete the project and to utilize it;

•it has capacity to utilize the intangible asset;

•there is proof of the probability of future economic benefits associated with the asset

•there is availability of the technical, financial and other resources for completing the project; and

•there is a reliable evaluation of the development expenses.

The initial measurement of the asset is the sum of expenses incurred starting on the date on which the development project meets the

above criteria. Because of the risks and uncertainties related to regulatory authorizations and to the research and development process,

the Group believes that the six criteria stipulated by IAS 38 have not been fulfilled to date and the application of this principle has

resulted in all development costs being expensed as incurred in all periods presented.

Other intangible assets

Other intangible assets mainly consist of acquired software. Costs related to the acquisition of software licenses are recognized as

assets based on the costs incurred to acquire and set up the related software. Other intangible assets are amortized using the straight-

line method over a period of one year.

Note 4.3. Property, plant and equipment

Pursuant to IAS 16 – Property, Plant and Equipment, property, plant and equipment are recognized at their acquisition cost (purchase

price and directly attributable costs) or at their production cost by the Group, as applicable.

Property, plant and equipment are depreciated using the straight-line method over the estimated useful life of the asset. The principal

useful lives applied are as follows:



	DEPRECIATION PERIOD
Buildings
Office fixtures and fittings	3 years (1)
Equipment
Industrial materials and equipment	5 to 10 years
Technical facilities	5 to 10 years
Furniture and computer equipment:
Office equipment	5 to 10 years
IT equipment	3 years
Furniture	10 years

(1)Office fixtures and fittings estimated useful lives correspond to the Headquarters residual estimated lease term.

The useful lives of property, plant and equipment as well as any residual values are reviewed at each year-end and, in the event of a

significant change, the depreciation schedule is revised prospectively.

Note 4.4. Impairment of goodwill, intangible assets, property and plant and equipment

Goodwill and intangible assets not yet available for use are not amortized and are tested for impairment annually.

In addition, the Group assesses at the end of each reporting period whether there is an indication that intangible assets and property,

plant and equipment may be impaired. Pursuant to IAS 36—Impairment of Assets, criteria for assessing indication of loss in value may

notably include performance levels lower than forecast, a significant change in market data or the regulatory environment, or

obsolescence or physical damage of the asset not included in the amortization/depreciation schedule.

For the purpose of impairment testing, goodwill and intangible assets not yet available for use are allocated to each of the Group’s

CGUs expected to benefit from synergies arising from the business combination or from the use of the intangible assets.

An impairment loss is recognized when the carrying amount of a CGU, including the goodwill, exceeds the recoverable amount of the

CGU. The recoverable amount of a CGU is the higher of the CGU’s fair value less cost to sell and value-in-use. The total impairment

loss of a CGU is allocated first to reduce the carrying amount of goodwill allocated to the CGU and then to the other assets of the

CGU pro-rata on the basis of the carrying amount of each asset in the CGU.

An impairment loss on goodwill is not reversed in a subsequent period. Impairment losses on intangible assets and property, plant and

equipment shall be reversed subsequently if the impairment loss no longer exists or has decreased.

Note 4.5. Financial assets

Financial assets at amortized cost

Other financial assets (advances, loans and deposits granted to third parties and other short-term investments) and other receivables are

non-derivative financial assets with fixed or determinable payments that are not listed on an active market. They are initially

recognized at fair value plus transaction costs that are directly attributable to the acquisition or issue of the financial asset.

IFRS 9 – Financial Instruments requires an entity to recognize a loss allowance for expected credit losses on a financial asset at

amortized cost at each statement of financial position date. The amount of the loss allowance for expected credit losses equal to: (i) the

12—month expected credit losses or (ii) the full lifetime expected credit losses. The latter applies if credit risk has increased

significantly since initial recognition of the financial instrument.

Cash and cash equivalents

The Group classifies investments as cash equivalents in the statements of financial position and statements of cash flows when they

meet the conditions of IAS 7—Statement of Cash Flows, i.e., when they are:

•held in order to face short-term cash commitments; and

•short term and highly liquid assets at acquisition date, readily convertible into known amount of cash and not exposed to

any material risk of change in value.

Note 4.6. Share capital

Ordinary shares are classified in shareholders’ equity. Costs associated with the issuance of new shares are directly accounted for in

shareholders’ equity in diminution of issuance premium.

The Group’s own shares bought in the context of a brokering/liquidity agreement entered with an independent broker are presented as

a reduction of shareholders’ equity until their cancellation, their reissuance or their disposal.

Note 4.7. Share-based payments

Since its inception, the Group has established several plans for compensation settled in equity instruments in the form of founders’

share subscription warrants (“bons de souscription de parts de créateur d’entreprise” or “BCE”), share subscription warrants (“Bons de

souscription d’actions,” or “BSA”) and free shares (“Attributions gratuites d’actions,” or “AGA”), granted to its employees, corporate

officers and scientific consultants.

Pursuant to IFRS 2—Share-based Payment, these awards are measured at their fair value on the date of grant. The values of the equity

instruments are determined using the option pricing model (in particular, a Black and Scholes model for the BCE and BSA plans and a

Monte-Carlo simulation for the AGA plans which include market performance vesting conditions) based on the value of the

underlying equity instrument at grant date, the volatility observed in a sample of comparable listed companies and the estimated life of

the related equity instruments.

The Group recognizes the fair value of these awards as a share-based compensation expense over the period in which the related

services are received, i.e. over the vesting period, with a corresponding increase in shareholders’ equity. Share-based compensation is

recognized by installments in consistency with their graded vesting schedule, when applicable.

The amount recognized as an expense is adjusted to reflect the number of awards for which the related service and non-market

performance conditions are expected to be met, such that the amount ultimately recognized is based on the number of awards that meet

the related service and non-market performance conditions at the vesting date.

For share-based payment awards with market vesting conditions and non-vesting conditions, the grant-date fair value of the share-

based payment is measured to reflect such conditions and there is no true-up for differences between expected and actual outcome.

The measurement of the fair value of BSA, BCE and AGA incorporates the market-based vesting conditions and non-vesting

conditions as described in Note 4.16 “Use of judgments and estimates”.

Note 4.8. Financial liabilities

Note 4.8.1. Financial liabilities at amortized cost

Pursuant to IFRS 9 – Financial Instruments, the borrowings, the debt component of the Kreos / Claret OCABSA (classified as

convertible loan notes – see Compound instruments Compound instruments below) and Other financial liabilities (conditional

advances and royalty certificates) other than financial derivative liabilities are measured at amortized cost. They are initially

recognized at fair value and subsequently measured at amortized cost calculated using the effective interest rate (“EIR”) method. The

transaction costs that are directly attributable to the issue of the financial liability reduce that financial liability. These expenses are

then amortized over the lifetime of the liability, on the basis of the EIR. The EIR is the rate that exactly discounts estimated future

cash payments through the expected life of the financial liability to the amortized cost of a financial liability. Financial liabilities that

are due within one year are presented as current financial liabilities in the statements of financial position.

Royalty certificates

Royalty certificates meet the definition of financial liabilities. The Group concluded that they do not include embedded derivatives

related to the variability of royalties that are based on future net sales. In addition, the Group concluded that the prepayment options

were separate derivative instruments as their redemption price did not reimburse holders for an amount up to the approximate present

value of lost interest for the remaining term of the host contracts. However, their value at inception and subsequent dates is nil and has

no impact on the financial statements.

Royalty certificates are initially measured at fair value (refer to note 15.10 for valuation model applied). They are subsequently

measured at amortized cost calculated using the EIR method. The EIR is calculated based on future cash flows, which are estimated on

the basis of development and commercialization plans and budgets approved by the Board of Directors of the Group, and probability-

weighted to reflect the probability of success of clinical studies and any other uncertainty affecting them. If there is a change in the

timing or amount of estimated cash flows, then the gross carrying amount of the amortized cost of the financial liability is adjusted in

the period of change to reflect the revised actual and estimated cash flows, with a corresponding income or expense being recognized

in profit or loss. The revised gross carrying amount of the amortized cost of the financial liability is calculated by discounting the

future revised estimated cash flows at the original EIR.

Conditional advances and State guaranteed loan – “PGE”

Accounting treatment for conditional advances and the State-guaranteed loan (Prêt garanti par l'Etat, "PGE") is set forth in Note 4.9.

Leases

Accounting treatment for lease liabilities is set forth in Note 4.12.

Note 4.8.2. Financial liabilities measured at fair value through profit or loss

Derivative instruments

BSA attached to Kreos 1 bonds, the conversion option of OCEANE, certain prepayment options of bonds and the Kreos / Claret

warrants are derivatives instruments. Derivatives are recognized initially at fair value at the date the derivative contract is entered into

and are subsequently remeasured to their fair value at each reporting date. The resulting gain or loss from change in the fair value is

recognized in profit or loss immediately, as financial expenses or income.

Hybrid instruments

OCEANE bonds and Heights convertible notes (whose characteristics are described in Note 15.2 and Note 15.5) are hybrid

instruments. A “hybrid contract” is a contract that includes both a non-derivative host contract and one or more embedded derivatives.

Embedded derivatives are required to be separated from the host contract (bifurcated) if: the economic characteristics and risks of the

embedded derivative are not closely related to those of the host, a separate instrument with the same terms as the embedded derivative

would meet the definition of a derivative, and the hybrid contract is not measured at fair value through profit or loss.

Separable embedded derivatives are required to be measured at fair value at each reporting date, with changes in fair value recognized

in profit or loss. The initial bifurcation of a separable embedded derivative does not result in any gain or loss being recognized.

Because the embedded derivative component is measured at fair value on initial recognition, the carrying amount of the host contract

on initial recognition is the difference between the carrying amount of the hybrid instrument and the fair value of the embedded

derivative. If the fair values of the hybrid instrument and host contract are more reliably measurable than that of the derivative

component - e.g. because of the availability of quoted market prices - then it may be acceptable to use those values to determine the

fair value of the derivative on initial recognition indirectly - i.e. as a residual amount.

The Heights convertible notes issued on August 24, 2023 included embedded derivatives as detailed in Note 15. The Group concluded

that these features were embedded derivatives that would modify the cash flows required under the contract and require to be

bifurcated from their host contract. The Group being unable to reliably value each embedded derivative at issuance date and on

subsequent reporting dates, it measured the whole hybrid instrument at fair value through profit or loss (“FVTPL”) as permitted by

IFRS 9. Instruments measured at FVTPL under these conditions are measured at their fair value on issuance and on subsequent

reporting dates, with changes in fair value recognized in profit or loss.

Compound instruments

The Kreos / Claret OCABSA are compound instruments (whose characteristics are described in Note 15.1). A “compound contract” is

a contract that includes both a debt component and an equity component. The debt component (excluding the conversion option and

the attached OCABSA warrants) is initially recognized at fair value and subsequently measured at amortized cost calculated using the

EIR method. The equity component corresponding to the conversion option and the attached OCABSA warrants is recorded in equity,

for the difference between the whole instrument’s fair value (its nominal value) and the standalone fair value of the debt component.

Fair value measurement

When measuring the fair value of an asset or a liability, the Company uses market observable data as far as possible. Fair values are

categorized into different levels in a fair value hierarchy based on the inputs used in the valuation techniques as follows:

•level 1: fair value calculated using quoted prices in an active market for identical assets and liabilities;

•level 2: fair value calculated using valuation techniques based on observable market data such as prices for assets and

liabilities or similar parameters quoted in an active market;

•level 3: fair value calculated using valuation techniques based in whole or in part on unobservable inputs such as prices

in an inactive market or a valuation based on multiples of unlisted securities.

See Note 12 Financial assets and liabilities, Note 15 Financial liabilities.

Note 4.9. Research tax credit, subsidies and conditional advances

Research tax credit

The Group benefits from the provisions of Articles 244c of the French General Tax Code relating to the French research tax credit

(“Crédit d’Impôt Recherche” or “CIR”). The CIR is granted to companies in order to encourage them to conduct technical and

scientific research. Companies that prove that they have expenditures which meet the required criteria (research expenditures located

in France or, since January 1, 2005, within the European Union or in another state that is a party to the Agreement on the European

Economic Area and has concluded a tax treaty with France that contains an administrative assistance clause) receive a tax credit that

can be used for the payment of the corporate tax due for the fiscal year in which the expenditures were made and the next three fiscal

years, or as applicable, companies may receive cash reimbursement for any excess portion at the three-year period following the fiscal

year of the expenditures. Only those companies meeting the EU definition of a small or medium-sized entity (“SME”) are eligible for

payment in cash of their research tax credit (to the extent not used to offset corporate tax payables) in the year following the request

for reimbursement. The expenditures taken into account for the calculation of the CIR involve only research expenses.

The CIR is presented under “Other operating income” in the statements of income (loss) as it is accounted for as a government grant

as defined in IAS 20 – Accounting for Government Grants and Disclosure of Government Assistance, and as “Other receivables and

assets” in the statement of financial position until its payment is received.

Subsidies

Subsidies are non-repayable grants received by the Group and recognized in the financial statements when there exists reasonable

assurance that the Group will comply with the conditions attached to the subsidies and the subsidies will be received.

Subsidies that are upfront payments are presented as deferred income and recognized through “Other operating income” for the

amount of the expenses incurred as part of the research program to which the subsidy relates.

A subsidy that is to be received either as compensation for expenses or for losses already incurred, or for immediate financial support

of the Group without associated future costs, is recognized in the Statements of income (loss) as “Other operating income” when there

exists reasonable assurance that the subsidies will be received.

Conditional advances and PGE

The Group receives conditional advances to finance at below market interest rate research and development projects. Due to the

innovative nature of its drug candidate development programs, the Group has benefited from certain sources of financial assistance

from Bpifrance. Bpifrance provides financial assistance and support to emerging French enterprises to facilitate the development and

commercialization of innovative technologies.

Funds received from Bpifrance in the form of conditional advances are recognized as financial liabilities, as the Group has a

contractual obligation to reimburse Bpifrance for such conditional advances in cash based on a repayment schedule. Each award of an

advance is made to help fund a specific development milestone. More tails on conditional advances are provided in Note 15.7.

Receipts or reimbursements of conditional advances are reflected as financing transactions in the statements of cash flows.

The difference between the present value of the advance at market rate (i.e., present value of contractual cash flows including principal

and interests, discounted using a market rate as effective interest rate in accordance with IFRS 9) and the amount received as cash

from the Bpifrance constitutes a subsidy within the meaning of IAS 20. Considering that these advances do not finance fixed assets,

these subsidies are presented as “Deferred income” in the statement of financial position and recognized in the statement of net income

(loss) as “Other operating income“ on a systematic basis over the periods in which the Group recognizes as expenses the related costs

for which the grants are intended to compensate.

The incremental interest expense resulting from the difference between (a) the market interest rate and the (b) below-market rate is

spread over the contractual period until the last repayment and recognized in the statement of income (loss) accordingly, using the EIR

method. In the event of a change in estimate of contractual cash flows due under the conditional advances, the Group recalculates the

book value of the debt resulting from the discounting of the anticipated new future cash flows at the initial EIR. The adjustment is

recognized in the statements of income (loss) for the period during which the modification is recognized.

In the statements of financial position, these conditional advances are recorded in “Other financial liabilities” as current or non-current

portion depending on their maturity. In the event Bpifrance waived the repayment of the advance, the corresponding liability is

derecognized and treated as a subsidy in the statements of income (loss).

The benefit resulting from the low interest of PGE loans is also recognized as a subsidy corresponding to the difference between the

present value of the PGE at market rate and the amount received as cash. The accounting treatment is therefore similar to the above-

mentioned accounting treatment for conditional advances. PGE are recorded in “Borrowings” as current or non-current portion

depending on their maturity.

Note 4.10. Employee benefits

The Group’s employees in France benefit from retirement benefits provided under French law, which consist in the following:

•compensation paid by the Group to employees upon their retirement (a defined benefit plan); and

•payments of retirement pensions by the social security agencies, which are financed by the contributions made by the

Group and employees. As they meet the definition of a defined contribution plan, the liabilities are presented as Tax and

employee-related payables in the statement of financial position.

In accordance with IAS 19 – Employee Benefits, the liability with respect to defined benefit plans is estimated by using the projected

credit unit method. According to this method, the cost of the retirement benefit is recognized in the statements of income (loss). The

retirement benefit commitments are valued at the current value of the estimated future payments, discounted using the market rate for

high quality corporate bonds with a term and currency that correspond to that estimated for the payment of the benefits. The Group

applied the decision of the IFRS IC, published on May 24, 2021, that concluded that, in the case that no rights were acquired in the

event of departure before retirement age and that the rights were capped after a certain number of years of seniority (“30 years”), the

commitment would only be recognized for the last 30 years of the employee’s career within the Group.

The difference between the amount of the provision at the beginning of a period and at the close of that period is recognized through

operating expenses for the portion representing the costs of services rendered and financial expenses for the net interest costs, and

through other comprehensive income (loss) for the portion representing the actuarial gains and losses due to changes in assumptions

and experience adjustments.

Note 4.11. Provisions

Provisions correspond to commitments resulting from litigation and various risks to which the Group may face in the context of its

operations. In accordance with IAS 37 – Provisions, Contingent Liabilities and Contingent Assets, a provision is recorded when the

Group has an obligation to a third party resulting from a past event that will likely result in an outflow of resources to the third party,

and for which future cash outflows may be estimated reliably. The amount recorded as a provision is an estimate of the expenditure

required to settle the obligation, discounted where necessary at year end.

Note 4.12. Leases

As lessee, the Group assesses whether a contract contains a lease at inception of a contract and upon the modification of a contract.

The Group elected to allocate the consideration in the contract to the lease and non-lease components on the basis of the relative

standalone price. The Group recognizes a right-of-use asset and a corresponding lease liability for all arrangements in which it is a

lessee, except for leases with a term of 12 months or less (short-term leases) and low-value leases (value of the underlying asset below

€5.0 thousand). For these short-term and low-value leases, the Group recognizes the lease payments as an operating expense on a

straight-line basis over the term of the lease.

The lease liability is initially measured at the present value of the future lease payments as from the commencement date of the lease

to the end of the lease term. The lease terms used by the Group reflect the non-cancellable terms of each contract, plus any extension

or termination options that the Group is reasonably certain to exercise or not exercise for all of the leases periods covered by the

extension options. The lease payments are discounted using the interest rate implicit in the lease or, if not readily determinable, the

Group incremental borrowing rate for the asset subject to the lease in the respective markets.

The Group remeasures the lease liability (and makes a corresponding adjustment to the related right-of-use asset) whenever there is a

change to the lease terms or expected payments under the lease, or a modification that is not accounted for as a separate lease. The

portion of the lease payments attributable to the repayment of lease liabilities and the portion attributable to payment of interests are

recognized in cash flows used in financing activities.

Right-of-use assets are initially recognized on the balance sheet at cost, which comprises the amount of the initial measurement of the

corresponding lease liability, adjusted for any lease payments made at or prior to the commencement date of the lease, any lease

incentives received and any initial direct costs incurred by the Group, and expected costs for obligations to dismantle and remove

right-of-use assets when they are no longer used.

Right-of-use assets are depreciated on a straight-line basis from the commencement date of the lease over the shorter of the useful life

of the right-of-use asset or the end of the lease term.

Right-of-use assets are assessed for impairment whenever there is an indication that the balance sheet carrying amount may not be

recoverable using cash flow projections.

Note 4.13. Translation of transactions denominated in foreign currency

Pursuant to IAS 21 – The Effects of Changes in Foreign Exchange Rates, transactions performed by the Group in currencies other than

their functional currency, which is the Euro, are translated at the prevailing exchange rate on the transaction date.

Trade receivables and payables and liabilities denominated in a currency other than the functional currency are translated at the

period-end exchange rate. Unrealized gains and losses arising on translation are recognized in net financial income / (loss).

Note 4.14. Current and deferred tax

Tax assets and liabilities for the current and prior periods are measured at the amount expected to be recovered from or paid to the

French tax authorities, using tax rates and tax laws enacted or substantively enacted at the end of the reporting period in accordance

with IAS 12 – Income Tax.

The income tax charge for the period comprises current tax due and the deferred tax charge. The tax expense is recognized in the

statement of income (loss) unless it relates to items recorded in other comprehensive income (loss) or directly in equity, in which case

the tax is also recorded in other comprehensive income (loss) or directly in equity.

Current taxes

The current tax expense is calculated based on taxable profit for the period, using tax rates enacted or substantively enacted at the

statement of financial position date. Considering the level of tax loss of the Group, no current tax expense is recognized.

Deferred taxes

Deferred taxes are recognized when there are temporary differences between the carrying amount of assets and liabilities in the

Group’s financial statements and the corresponding tax basis used to calculate taxable profit. Deferred taxes are not recognized if they

arise from the initial recognition of an asset or liability in a transaction other than a business combination which, at the time of the

transaction, does not affect either the accounting or the taxable profit (tax loss).

The Group applies the Amendments to IAS 12 – Deferred Tax related to Assets and Liabilities arising from a Single Transaction,

issued on May 7, 2021, and presents the deferred tax assets and liabilities arising from such transactions separately within Note 22 -

Income tax, rather than on a net basis. The Amendments have no impact on the Statements of financial position and the Statement of

comprehensive income (loss) for the periods presented.

Deferred tax assets

Deferred tax assets are recognized for all deductible temporary differences, unused tax losses and unused tax credits to the extent that

it is probable that the temporary difference will reverse in the foreseeable future and that taxable profit will be available against which

the deductible temporary difference, unused tax losses or unused tax credits can be utilized. See Note 4.16. Use of judgments and

estimates and Note 22. Income tax.

Note 4.15. Accounting of Prosynergia acquisition

From April 1, 2022 up until the merger completed on December 12, 2022, the Company owned a 100% ownership interest of

Prosynergia and as such, controlled Prosynergia. The Company had power over Prosynergia, was exposed or had rights to variable

returns from its involvement with the entity and had the ability to affect those returns through its power over the entity.

The financial statements of Prosynergia were therefore included in the consolidated financial statements of the Company from the date

control was obtained, i.e. April 1, 2022. Prosynergia was merged into the Company in December 12, 2022.

Considering that Prosynergia only owned patent rights but did not enter into any employee contract, research agreement, collaboration

agreement or out-licensed agreement, it did not meet the definition of a business under IFRS 3. Consequently, the acquisition cost of

this group of assets was allocated between the identifiable assets and liabilities acquired, pro rata to their respective fair values as of

April 1, 2022, without recognition of goodwill. For this purpose, the following approach was applied: first measurement of any

identifiable asset or liability initially measured at an amount other than cost in accordance with the applicable standards, deduction

from the cost of the group of assets of the amounts allocated to these assets and liabilities, and then allocation of the residual cost of

acquisition to the remaining identifiable assets and liabilities based on their relative fair values at the date of acquisition.

Also, the €1,400 thousand loan granted to Prosynergia in December 2021 was included in the acquisition cost to be allocated, since, in

substance, it was considered as a prepayment for the acquisition of the group of assets, which is repayable in cash in the event of non-

completion of the transaction.

The potential earn-out payment to be paid in the first half of 2023 was measured at fair value on April 1, 2022, for an amount of

€1,446 thousand, and included in the acquisition cost. This earn out could be triggered in the event the Group’s market capitalization

was in excess of €300 million (valued at certain specified record dates), a listing of the Group’s shares on Nasdaq or a merger and

acquisition transaction prior to March 31, 2023. The amount of the earn-out was equal to 1% of the difference between the Group’s

market capitalization and €300 million, subject to a maximum amount of €4.0 million. It was payable in the first half of 2023 if

conditions were met. No amount was payable in the event the Group’s market capitalization was lower than €300 million. The related

financial liability was subsequently remeasured to its fair value as of December 31, 2022 estimated to nil (see Note 15.9). The

remeasurement resulted in a financial income of €1,446 thousand over the year ended December 31, 2022.

As a consequence of the earn-out condition not being met on March 31, 2023, the related financial liability was derecognized.

The allocation of the acquisition cost is as follows:



(Amounts in thousands of euros)	Amount allocated as of April 1, 2022
Cash prepayment made in 2021 ........	325
Loan granted to Prosynergia in 2021	1,400
Cash payment made in 2022 .............	2,925
Acquisition fees (1) ...........................	466
Earn-out measured at fair value ........	1,446
Total acquisition cost allocated ......	6,562

Patents ...............................................	6,529
Cash and cash equivalents ................	42

Total assets ......................................	6,571

Total liabilities .................................	(9)

Total net assets ................................	6,562

(1)Of which €451 thousand were disbursed in 2021 and €15 thousand in 2022. Acquired cash amounts to €42 thousand.

The acquisition cost was mainly allocated to Prosynergia’s patents US 10,464,903 (filed on March 20, 2017 and granted on November

5, 2019), EP3 429 998 (filed on March 20, 2017 and granted on September 1, 2021) and continuation US 10,745,357 (filed on

November 1, 2019 and granted on August 18, 2020). All patents will expire in 2037.

These patents cover alternative synthesis process for obefazimod and a family of close chemical analogues. They also cover

alternative forms of obefazimod (salts thereof and crystalline forms of said salts), the pharmaceutical composition comprising them,

that could be of interest to the Company for future development.

Note 4.16. Use of judgments and estimates

In order to prepare financial statements in accordance with IFRS, estimates, judgments and assumptions were made by the Group’s

management which could affect the reported amounts of assets, liabilities, contingent liabilities, income and expenses.

These estimates are based on the assumption of going concern and are prepared in accordance with information available at the date

the financial statements were prepared. They are reviewed on an ongoing basis using past experience and various other factors

considered to be reasonable as the basis to measure the carrying amount of assets and liabilities. Estimates may be revised due to

changes in the underlying circumstances or subsequent to new information. Actual results may differ significantly from these

estimates in line with assumptions or different conditions.

This note provides an overview of the areas that involved a higher degree of judgement or complexity, and of items which are more

likely to be materially adjusted due to changes in estimates and assumptions. Detailed information about each of these estimates and

judgements is included in other notes together with information about the basis of calculation for each affected line item in the

financial statements.

•Recognition and measurement of impairment of CGUs. The main assumptions used for the impairment test include

(a) the amount of cash flows that are set on the basis of the development and commercialization plans and budgets

approved by Board of Directors, (b) assumptions related to the achievement of the clinical trials and the launch of the

commercialization, (c) the discount rate, (d) assumptions on risk related to the development and (e) for the

commercialization, selling price and volume of sales. The sensitivity analysis in respect of the recoverable amount of the

CGUs is presented in Note 6.

•Measurement of share-based payments granted to employees, corporate officers and scientific consultants, such as BCE,

BSA and AGA, which is based on actuarial models; these models require the use by the Group of certain calculation

assumptions such as the estimated vesting, the occurrence dates of a change of control or a M&A transaction dates, the

percentage of success (“POS”) of obefazimod, the expected volatility and maturity of the underlying equity instrument

(see Note 4.7 and Note 14),

•Fair value measurement at inception and after of derivative financial instruments resulting from (i) the warrants issued

concomitantly with the issuance of the straight and convertible bonds to Kreos on July 24, 2018 (or “Kreos 1”), (ii) the

prepayment option attached to the straight and convertible bonds issued to Kreos on October 2, 2020 (or “Kreos 2”), and

(iii) the prepayment option attached to the issuance of bond convertible into new or existing shares in July 30, 2021 (or

“OCEANE”) (see Notes 15), (iv) the Kreos / Claret BSA issued on August 21, 2023 and November 2, 2023, related to

tranches A-B and tranche C, respectively.

•Fair value measurement of financial liabilities at inception (see Note 15), and after (for the Heights convertible notes

issued on August 24, 2023) measured at fair value at each reporting period, with fair value changed recognized in profit

or loss,

•Amortized cost measurement of royalty certificates, based on the following assumptions: (a) future cash flows, estimated

on the basis of development and commercialization plans and budgets approved by the Board of Directors and (b) the

effective interest rate. The sensitivity analysis in respect of the measurement of royalty certificates is presented in Note

15,

•Fair value measurement of the call option resulting from the equity line contracts entered into on September 30, 2019 (or

“Equity lines”) (see Note 13.2),

•Estimation of CIR, based on internal and external expenses, which meet the required criteria, incurred by the Company

each year (see Note 4.9),

•Recognition of deferred tax assets: availability of future taxable profit against which deductible temporary differences

and tax losses carried forward can be utilized and whether sufficient evidence exists (see Note 22).

•Recognition of deferred tax assets: tax deductibility of future royalty payments related to the royalty certificates issued in

September 2022 (see Notes 15 and 22).

The main critical judgments made by the Group’s management impact the following items:

•Accounting treatment of specific conditions of share-based compensation plans (see Notes 4.7 and 14).

•Accounting treatment of the 2018 & 2020 Kreos 1 & 2 bonds, the 2021 OCEANE bonds, and the August 2023 Kreos /

Claret and Heights Financings (see Notes 4.8 and 15).

Management and assessment of financial risks (Details)	12 Months Ended
Management and assessment of financial risks (Details)	Dec. 31, 2023 EUR (€) financial_institution	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)
Disclosure of credit risk exposure [line items]
Operating expense	€ 131,997,000	€ 69,419,000	€ 53,361,000
Currency risk
Disclosure of credit risk exposure [line items]
Reasonably possible change in risk variable, impact on foreign exchange		0	0
Credit risk
Disclosure of credit risk exposure [line items]
Number of financial institutions to maintain cash \| financial_institution	2
Balances with banks in excess of legally insured limit	€ 251,616,000
United States of America, Dollars
Disclosure of credit risk exposure [line items]
Operating expense	€ 10,112,000	€ 1,390,000	€ 1,262,000
United States of America, Dollars \| Currency risk
Disclosure of credit risk exposure [line items]
Reasonably possible change in risk variable, percent	10.00%
Reasonably possible change in risk variable, impact on foreign exchange	€ 386,000

Share-based payments

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangements [Abstract]

Share-based payments

The Group has granted BCEs, BSAs and free shares (attributions gratuities d’actions, or “AGAs”). These plans qualify as “equity

settled” under IFRS 2. The Group does not have any obligation to purchase these instruments in the event of departure or if a specific

event does not occur.

Valuation methods of BCEs, BSAs and AGAs

The fair value of share-based awards was determined at grant date using the Black Scholes model for the BCEs and BSAs and the

Monte-Carlo simulation for AGAs plans with market performance conditions.

The assumptions used to estimate the fair value of the instruments are presented below and include:

•Expected maturity of the options;

•Expected volatility based on the historical market share price available;

•Expected dividends based on management best estimate;

•Risk-free interest rate based on French OAT rates measured at grant dates;

•Share price, including offered in case of change of control (only for the market conditions applicable to the free-share plans

AGA 2021 and AGA 2023-1) is based on Monte-Carlo simulations and taking into account a change of control premium

based on the management best estimate.

BCEs

The following tables summarize the data relating to BCEs as well as the assumptions used for the measurement thereof in accordance

with IFRS 2 – Share-based Payment:


GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BCEs	NUMBER OF EXERCISED BCEs	NUMBER OF BCEs OUTSTANDI NG	NUMBER OF BCEs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITION S ARE MET
GRANT DAT E	TYPE	NUMBER OF BCEs ISSUED	NUMBER OF BCE OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BCE-2014-2	2,750	1,000	—	(1,000)	—	—	—
2014-03-11	BCE-2014-4	984	184	—	(184)	—	—	—
2016-11-07	BCE-2016-1	84,000	22,495		—	22,495	22,495	22,495
2017-01-23	BCE-2017-1	67,374	67,000	—	—	67,000	41,735	67,000
2017-11-20	BCE-2017-2	150,000	150,000	(37,500)	—	112,500	112,500	112,500
2017-11-20	BCE-2017-4	67,374	67,373	—	—	67,373	33,686	67,373
2017-11-20	BCE-2017-5	67,374	64,374	—	—	64,374	30,686	64,374
2018-03-15	BCE-2018-1	22,000	11,980		—	11,980	11,980	11,980
2018-05-14	BCE 2018-3	33,687	16,844	—	—	16,844	—	16,844
2018-05-14	BCE-2018-4	16,843	16,843	0	—	16,843	8,422	16,843
2018-05-14	BCE-2018-5	22,000	6,000			6,000	6,000	6,000
	Total BCEs	534,386	424,093	(37,500)	(1,184)	385,409	267,504	385,409

The BCEs include a service condition under which the beneficiary must still be an employee, a corporate officer or a scientific

consultant of the Group at the time of vesting.

The exercise rights for most of the BCEs are vested annually and have the following vesting terms:

•25% of the award vests on the first anniversary of the date of grant for all currently issued BCEs; and

•For the remaining 75% of the award, the BCEs vest 1/48th per month over four years from the anniversary date of the grant.

Most of the BCEs plans (all BCEs plans except BCE 2014-2 fully vested as of January 1, 2020) include or partially include non-

market performance conditions (obtaining financing of €100 million, positive results on clinic studies, signature of informed consent

in a clinical phase, signing a license agreement, FDA authorization). The level of achievement of the non-market performance

conditions are taken into account in determining the number of BCEs allocated initially and reassessed at each closing date.

In the event of a change of control or a M&A transaction, all the BCEs will become immediately exercisable. A change of control is

defined as a new investor/company holding directly or indirectly more than 50% of the share capital or voting rights. As such the

probable vesting date of each plan corresponds to the weighted average of probable change of control dates.

BSAs

The following tables summarize the data relating to BSAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	NUMBER OF LAPSED BSAs	NUMBER OF EXERCISED BSAs	NUMBER OF BSAs OUTSTANDI NG	NUMBER OF BSAs EXERCISAB LE	MAXIMUM NUMBER OF SHARES TO BE ISSUED IF ALL CONDITIONS ARE MET
GRANT DATE	TYPE	NUMBER OF BSAs ISSUED	NUMBER OF BCAs OUTSTANDI NG AS OF JANUARY 1, 2023	YEAR ENDED DECEMBER 31, 2023		AS OF DECEMBER 31, 2023
2014-03-11	BSA-2014-3	1,172	492	—	(492)	—	—	—
2015-12-04	BSA-2015-11	96,924	96,924	—	—	96,924	96,924	96,924
2015-12-04	BSA-2015-12	82,000	16,400	—	—	16,400	16,400	16,400
2017-09-18	BSA-2017-1	16,400	16,400	—	—	16,400	16,400	16,400
2018-01-22	BSA-2018-1	49,200	16,400	—	—	16,400	16,400	16,400
2014-03-11	BSA-2014-4	1,315	842	—	—	842	842	84,160
2014-03-11	BSA-2014-5	787	459	—	(230)	230	230	22,950
	Total BSAs	247,798	147,917	—	(722)	147,196	147,195	253,234

The BSAs include a service condition under which the beneficiary must still be an employee, a corporate officer or a scientific

consultant of the Group at the time of vesting.

The exercise rights for most of the BSAs are vested annually and have the following vesting terms:

•25% of the award vests on the first anniversary of the date of grant for all currently issued BSAs; and

•For the remaining 75% of the award, the BSAs vest 1/48th per month over four years from the anniversary date of the grant.

All of the BSAs plans include or partially include non-market performance conditions (positive results on clinic studies, signature of

informed consent in a clinical phase, signing a license agreement, FDA authorization). The level of achievement of the non-market

performance conditions are taken into account in determining the number of BSAs allocated initially and reassessed at each closing

date.

In the event of a change of control or a M&A transaction, all the BSAs will become immediately exercisable. A change of control is

defined as a new investor/company holding directly or indirectly more than 50% of the share capital or voting rights. As such the

probable vesting date of each plan corresponds to the weighted average of probable change of control dates.

AGAs

The following tables summarize the data relating to AGAs as well as the assumptions used for the measurement thereof in

accordance with IFRS 2—Share-based Payment:


GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	NUMBER OF AGAs OUTSTANDING
GRANT DATE	TYPE	NUMBER OF AGAs ISSUED	NUMBER OF AGAs OUTSTANGING AS OF JANUARY 1, 2023	NUMBER OF LAPSED AGAs	NUMBER OF EXERCISED AGAs	AS OF DECEMBER 31, 2023
2023-07-11	AGA-2023-1	1,382,796	—	—	—	1,382,796
2023-07-11	AGA-2023-2	100,000	—	—	—	100,000
2023-09-28	AGA-2023-3	731,500	—	—	—	731,500
2023-09-28	AGA-2023-4	254,250	—	—	—	254,250
2023-12-01	AGA-2023-5	132,750	—	—	—	132,750
	Total AGAs	2,601,296	—	—	—	2,601,296


TYPE	FAIR VALUE OF THE UNDERLYING SHARE	FAIR VALUE OF THE AGA	AGA PRICE	MATURITY	VOLATILITY	RISK FREE RATE
AGA 2021	€31.60	€23.92	0.00 €	2022-07-31	49.0%	-1.00%
AGA 2023-1 (Tranches 1-4)	€15.98	€15.98	0.00 €	N/A	N/A	N/A
AGA 2023-1 (Tranche 5)	€15.98	€3.62	0.00 €	2024-12-31	67.2%	3.20%
AGA 2023-1 (Tranche 6)	€15.98	€0.74	0.00 €	2024-07-11	67.2%	3.20%
AGA 2023-2 (Tranche 1)	€15.98	€15.98	0.00 €	N/A	N/A	N/A
AGA 2023-2 (Tranche 2)	€15.98	€9.59	0.00 €	N/A	N/A	N/A
AGA 2023-3	€14.92	€14.92	0.00 €	N/A	N/A	N/A
AGA 2023-4	€14.92	€14.92	0.00 €	N/A	N/A	N/A
AGA 2023-5	€9.16	€9.16	0.00 €	N/A	N/A	N/A

•AGAs granted in September 2021

AGAs granted in September 2021 are subject to a vesting service condition of one year following the grant date. The number of shares

that will be finally vested under this plan will depend on the following conditions: if a M&A transaction is completed on or prior to

July 31, 2022 and the price per ordinary share of the Group retained in the framework of the M&A transaction is at least equal to €100

per share (or lower than €100 per share) then 100% (or 75%) of the shares initially granted will be vested. The AGAs are forfeited if a

M&A transaction is not completed on or prior to July 31, 2022.

These conditions qualify as both a non-market performance condition (occurrence or not of a M&A transaction before July 31, 2022)

and a market condition (number of shares depending on the share price offered in case of a M&A transaction before July 31, 2022)

under IFRS 2 principles.

The level of achievement of the market condition is directly included in the unit fair value of the free shares and the probability of a

M&A transaction before July 31, 2022 is included in the estimation of the number of shares that will be finally vested by the

beneficiaries.

As of December 31, 2021, considering that it was probable that an M&A transaction would occur before July 31, 2022, 100% of the

shares originally granted were included in the calculation of share based payment expenses. In addition, the Group recognized an

accrual for social taxes related to the AGA 2021 plan of €205 thousand as of December 31, 2021.The total share-based compensation

expense amounted to €828 thousand (€389 thousand in research and development and €440 thousand in general and administrative,

respectively).

During the period ended December 31, 2022, the AGAs were all forfeited since no M&A transaction was completed on or prior to

July 31, 2022. This resulted in a reversal of the related compensation expense of €1,026 thousand and the reversal of the accrual for

social taxes of €205 thousand that was recorded as of December 31, 2021.

AGAs granted in July 2023

(a) Pursuant to a Board decision on July 11, 2023, the Group allocated a total number of 1,382,796 AGAs to Mr Marc de Garidel, as

the Group’s Chief Executive Officer, to which performance conditions and service conditions apply (AGA plan 2023-1):

•For 212,738 AGAs 2023-1 (tranche 1): the acquisition period shall end on the first anniversary of the allocation date;

•For 638,214 AGAs 2023-1 (tranche 2): the AGAs 2023-1 shall progressively be definitively acquired on a monthly basis over

a period of three years starting after the first anniversary of the allocation date;

•For 212,738 AGAs 2023-1 (tranche 3): the acquisition period shall end on the latest date between (i) the first anniversary of

the allocation date, and (ii) the date on which a specific performance condition related to regulatory approval is fulfilled;

•For 106,369 AGAs 2023-1 (tranche 4): the acquisition period shall end on the latest date between (i) the first anniversary of

the allocation date, and (ii) the date on which the Group successfully completes a public offering raising at least $100 million

in gross proceeds (the condition was met on October 24, 2023);

•For 106,369 AGAs 2023-1 (tranche 5): the acquisition period shall end on the latest date between (i) the first anniversary of

the allocation date, and (ii) the date on which a specific performance condition related to the Group’s market capitalization is

fulfilled;

•For 106,368 AGAs 2023-1 (tranche 6): the acquisition period shall end on the first anniversary of the allocation date subject

to the completion, prior to such date, of a tender offer on the securities issued by the Group, at a predetermined minimum

price, and resulting in a change of control of the Group;

•Additionally, AGAs related to tranches 1 to 5 are subject to a vesting acceleration condition in case of a tender offer on the

securities issued by the Group and resulting in a change of control of the Group.

The Group qualified those conditions under IFRS 2 principles as follows:

•Conditions related to tranches 1 and 2 qualify as service conditions under IFRS 2 principles.

•Conditions related to tranches 3 and 4 qualify as service and non-market performance conditions. Their levels of achievement

are reflected in the number of instruments that are expected to vest and were estimated by management based on observable

industry-specific data.

•Conditions related to tranches 5 and 6 qualify as service and market performance conditions. The levels of achievement of

market conditions are reflected in the unit fair value of the free shares and were estimated by management using the valuation

methods and assumptions set out above. The valuation of tranche 6 also incorporates management’s estimate of the

probability of a M&A transaction prior to the limit date.

•The vesting acceleration condition in case of a tender offer on the securities issued by the Group and resulting in a change of

control of the Group qualifies as a non-market performance condition.

(b) Pursuant to a Board decision on July 11, 2023, the Group allocated a total number of 100,000 AGAs to Mr. Hartmut Ehrlich, as the

Group’s former Chief Executive Officer to which the following conditions apply (AGA plan 2023-2):

•For 25,000 AGAs 2023-2 (tranche 1): the acquisition period shall end on the first anniversary of the allocation date, and is

not subject to a future service condition;

•For 75,000 AGAs 2023-2 (tranche 2): the acquisition period shall end on the latest date between (i) the first anniversary of

the allocation date, and (ii) the date on which a specific condition, related to positive results on clinical studies, is fulfilled.

The acquisition is not subject to a future service condition. Additionally, the tranche is subject to a vesting acceleration

condition in case of a tender offer on the securities issued by the Group and resulting in a change of control of the Group.

This tranche qualifies as a non-vesting condition. Its level of achievement is reflected in the unit fair value of the free shares,

and was estimated by management based on observable industry-specific data.

AGAs granted in September and December 2023

On September 28, 2023 and December 1, 2023, certain of the Group’s officers and employees were allocated respectively 985,750

AGAs (AGA plans 2023-3 and 2023-4) and 132,750 AGAs (AGA plan 2023-5) in the aggregate, the vesting of which is subject to

certain conditions:

•Subject to remaining employed with the Group, each such officer or employee’s AGAs will be vested as follows: (i) 50% at

the end of a two-year period from the allocation date, (ii) 25% at the end of a three-year period from the allocation date and

(iii) 25% at the end of a four-year period from the allocation date (service condition).

•Of the 1,118,500 AGAs, 254,250 AGAs are subject to an additional non-market performance condition of the successful

completion of a public offering raising at least $200 million in gross proceeds. This condition was met on October 24, 2023.

Additionally, all the 2023-3, 2023-4 and 2023-5 AGAs are subject to a vesting acceleration condition in case of a tender offer on the

securities issued by the Group and resulting in a change of control of the Group.

Breakdown of the compensation expenses accounted for the period ended December 31, 2021, 2022 and 2023


TYPE (in thousands of euros)	YEAR ENDED DECEMBER 31, 2021	YEAR ENDED DECEMBER 31, 2022	YEAR ENDED DECEMBER 31, 2023
BCEs	(199)	(138)	(112)
BSAs	—	—	—
AGAs	1,026	(1,026)	(8,067)
Social taxes related to AGAs	205	(205)	(426)
Total	1,032	(1,369)	(8,605)

Goodwill and impairment test	12 Months Ended
Goodwill and impairment test	Dec. 31, 2023
Intangible assets and goodwill [abstract]
Goodwill and impairment test	Goodwill and impairment test Goodwill relates to the acquisition of Splicos SAS and Wittycel SAS that occurred in 2014 (i.e., prior the transition date to IFRS), which were merged into the Group in the same year. Goodwill from Splicos SAS and Wittycel SAS acquisition corresponds to the “Modulation of RNA biogenesis / splicing” technological platform and the “iNKT agonists” technological platform, respectively, from which derived the lead drug candidates of the Group: ABX464 and ABX196, respectively. IFRS 3 was not applied to acquisitions of subsidiaries deemed to be a business within the meaning of IFRS, carried out before the IFRS transition date, i.e., January 1 2020. Due to the application of this exemption, the previous accounting for business combinations in accordance with French GAAP remains unchanged (no identified Intellectual Property, Research & Development (“IPR&D”) assets are recognized in the statement of financial position). The carrying amounts of the goodwill resulting from Splicos SAS and Wittycel SAS acquisitions were, as of December 31, 2021, €18,419 thousand and €13,586 thousand, respectively. In accordance with IAS 36, goodwill is allocated to CGUs at a level corresponding to the lead drug candidates. Thus, goodwill from Splicos SAS and Wittycel SAS are allocated to ABX464 CGU and ABX196 CGU, respectively. Goodwill impairment tests are undertaken annually or more frequently if events or changes in circumstances indicate a potential impairment, in accordance with IAS 36. The carrying amount of goodwill is compared to the recoverable amount, which is the higher value in use and the fair value less costs to disposal. As of December 31, 2021, 2022 and 2023 the recoverable amount used for the impairment test of each CGU was the value in use. This value in use was based on a net present value calculation, using the following assumptions as of December 31, 2021, 2022 and 2023: •Cash flows are set on the basis of the development and commercialization plans and budgets approved by Board of Directors; •A discount rate (or “WACC”) of 15% as of December 31, 2023, 14% as of December 31, 2022 and 13.5% as of December 31, 2021; •A risk of development is taken into consideration by applying probabilities of success (or “POS”) of reaching future phases of development to cash flows related to the commercialization phase. Those average probabilities of success of R&D projects are based on public sources (INFORMA databases). •For the commercialization phase, selling price and sales volume are estimated on the basis of the potential market and the observed performances of comparable drugs currently on the market. The impairment tests resulted in no impairment charges as of December 31, 2021 and 2023. During the year ended December 31, 2022, management took into account significant external changes in the hepatocellular carcinoma (HC) treatment landscape. These changes were expected to require a new, lengthy, heavy and risky internal development process (use of a combination of compounds). For this purpose, entering into a licensing partnership to fund the completion of the clinical development of ABX196 was being considered. As of December 31, 2022, due to the lack of progress made in the negotiation of a development partnership, the Group made the decision to freeze the development program for ABX196 in the treatment of hepatocellular cancer. In this context, the impairment test carried out as of December 31, 2022 resulted in the full impairment of the goodwill resulting from the acquisition of Wittycell SAS and other assets included in the ABX196 CGU, i.e. an impairment loss of €13,632 thousand as of December 31, 2022 (€13,586 thousand related to goodwill and €45 thousand related to other assets – see Note 7). Sensitivity testing as of December 31, 2021, 2022 and 2023: The Group has conducted an analysis of the sensitivity of the impairment tests to changes in the key assumptions used to determine the recoverable amount of the CGUs to which goodwill is allocated. Regarding ABX464, as the product is currently under development, a clinical trial failure or a failure to obtain a marketing approval could result in an impairment. The results of the impairment test indicate a headroom level that is high enough so that any reasonably possible change in any of the key assumptions (except clinical failure) would not lead to any impairment. Regarding ABX196: •as of December 31, 2022, as above-mentioned, the net book value of the CGU was brought to zero after recording an impairment of €13,632 thousand. •as of December 31, 2021, an increase in WACC of 3.7 percentage points, or a reduction in sales of 22%, or a reduction in POS per phase of 10%, would result in the recoverable value being equal to the net book value.

Shareholders’ equity - Equity line instruments (Details) - BSAs			1 Months Ended	12 Months Ended
	Oct. 01, 2022 shares	Sep. 24, 2021	Sep. 30, 2019 criteria shares	Dec. 31, 2023 shares	Dec. 31, 2022 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of instruments lapsed (in shares)				0
Equity line agreement with Kepler Cheuvreux
Disclosure of terms and conditions of share-based payment arrangement [line items]
Maximum number of shares issued (in shares)			730,000
Maximum period			24 months
Number of trading days \| criteria			2
Maximum discount			7.00%
Extended period		12 months
Number of instruments lapsed (in shares)	300,000				300,000

Income (loss) per share - Schedule of earnings per share (Details) - EUR (€) € / shares in Units, € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings per share [abstract]
Weighted average number of outstanding shares, basic loss per share (in shares)	43,066,012	19,092,442	15,455,991
Weighted average number of outstanding shares, diluted loss per share (in shares)	43,066,012	19,092,442	15,455,991
Net loss for the period	€ (147,740)	€ (60,740)	€ (42,452)
Basic loss per share (in euro per share)	€ (3.43)	€ (3.18)	€ (2.75)
Diluted loss per share (in euro per share)	€ (3.43)	€ (3.18)	€ (2.75)

- Definition

The total of income less expenses from continuing and discontinued operations, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

+ References

+ Details

Off-balance sheet commitments received and contingent assets (Details) € in Thousands	Dec. 31, 2023 EUR (€)
Kreos & Claret financing
Disclosure Of Commitments Received [Line Items]
Undrawn borrowing facilities	€ 25,000
Heights convertible notes, tranche B
Disclosure Of Commitments Received [Line Items]
Undrawn borrowing facilities	40,000
RNP-VIR conditional advance
Disclosure Of Commitments Received [Line Items]
Undrawn borrowing facilities	3,255
CARENA conditional advance
Disclosure Of Commitments Received [Line Items]
Undrawn borrowing facilities	€ 1,853

Financial liabilities - Disclosure of variation in lease liabilities (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of financial liabilities [abstract]
Lease liabilities at beginning of period	€ 1,384	€ 214	€ 400
Increase	350	1,476	62
Decrease	(1,194)	(305)	(249)
Lease liabilities at end of period	€ 540	€ 1,384	€ 214

Financial assets and liabilities (Details) € in Thousands	Dec. 31, 2023 EUR (€)	Aug. 22, 2023 EUR (€)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets	€ 327,062		€ 75,544	€ 109,230
Financial assets, at fair value	301,500		47,452	76,827
Financial liabilities, at fair value	€ 125,191		58,469	82,491
Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Percentage of reasonably possible increase in unobservable input, liabilities	1.00%
Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Percentage of reasonably possible increase in unobservable input, assets	1.00%
Percentage of reasonably possible increase in unobservable input, liabilities	1.00%
LIABILITIES AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	€ 30,037		566	9,932
LIABILITIES AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	95,154		57,903	72,559
Financial liabilities-non current portion
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	61,274		28,771	52,589
Financial liabilities-non current portion \| LIABILITIES AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	18,506		566	9,932
Financial liabilities-non current portion \| LIABILITIES AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	42,768		28,205	42,657
Financial liabilities-current portion
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	16,696		14,224	11,345
Financial liabilities-current portion \| LIABILITIES AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	11,531		0	0
Financial liabilities-current portion \| LIABILITIES AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	5,165		14,224	11,345
Trade payables and other current liabilities
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	47,221		15,475	18,558
Trade payables and other current liabilities \| LIABILITIES AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	0		0	0
Trade payables and other current liabilities \| LIABILITIES AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities, at fair value	47,221		15,475	18,558
ASSETS AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	0		0	0
ASSETS AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	301,500		47,452	76,827
Recurring fair value measurement
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets	301,161		47,889	76,827
Financial liabilities	124,266		65,272	80,143
Recurring fair value measurement \| Financial liabilities-non current portion
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities	€ 60,349		€ 35,573	€ 50,240
Recurring fair value measurement \| Kreos 1 & 2 bond loans \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Significant unobservable input, liabilities			0.1475	0.1058
Decrease in financial liabilities at fair value			€ 68	€ 209
Recurring fair value measurement \| Oceane \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value			€ 476	€ 648
Recurring fair value measurement \| Kreos / Claret convertible notes (OCABSA) \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Significant unobservable input, liabilities	0.0900	0.0960
Decrease in financial liabilities at fair value	€ 538	€ 624
Recurring fair value measurement \| Conditional advances and PGE loan \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Significant unobservable input, liabilities	0.0900		0.1475	0.0850
Recurring fair value measurement \| PGE \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value	€ 39		€ 55	€ 102
Recurring fair value measurement \| RNP-VIR conditional advance \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value	15		31	61
Recurring fair value measurement \| CARENA conditional advance \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value	37		37	58
Recurring fair value measurement \| Ebola conditional advance \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value	1		1	3
Recurring fair value measurement \| Covid-19 conditional advance \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial liabilities at fair value				161
Recurring fair value measurement \| Financial liabilities-current portion
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities	16,696		14,224	11,345
Recurring fair value measurement \| Trade payables and other current liabilities
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial liabilities	47,221		15,475	18,558
Other financial assets
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	22,394		11,271	1,342
Other financial assets \| ASSETS AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	0		0	0
Other financial assets \| ASSETS AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	22,394		11,271	1,342
Other financial assets \| Recurring fair value measurement
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets	22,055		11,708	1,342
Other receivables and assets
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	27,164		9,231	14,784
Other receivables and assets \| ASSETS AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	0		0	0
Other receivables and assets \| ASSETS AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	27,164		9,231	14,784
Other receivables and assets \| Recurring fair value measurement
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets	27,164		9,231	14,784
Cash and cash equivalents
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	251,942		26,950	60,701
Cash and cash equivalents \| ASSETS AT FAIR VALUE THROUGH PROFIT AND LOSS
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	0		0	0
Cash and cash equivalents \| ASSETS AT AMORTIZED COST
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets, at fair value	251,942		26,950	60,701
Cash and cash equivalents \| Recurring fair value measurement
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Financial assets	251,942		26,950	€ 60,701
Long-term advances made to CROs \| Recurring fair value measurement \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Decrease in financial assets at fair value	€ 23		€ 240
Long-term advances made to CROs \| Recurring fair value measurement \| Bottom of range \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Significant unobservable input, assets	0.0104		0.0016
Long-term advances made to CROs \| Recurring fair value measurement \| Top of range \| Credit spread \| Discounted cash flow
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Significant unobservable input, assets	0.0218		0.0476

Financial liabilities - Lease liabilities (Details) - EUR (€) € in Thousands	1 Months Ended			12 Months Ended
	Nov. 30, 2023	Sep. 30, 2023	Jul. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure Of Lease Liabilities [Line Items]
Expense on lease liabilities				€ 548	€ 424	€ 250
Depreciation expense, lease				498	414	244
Interest expense on lease liabilities				13	10	5
Expense relating to short-term leases				€ 334	€ 331	€ 25
Lease facilities, Paris
Disclosure Of Lease Liabilities [Line Items]
Lease, duration period			3 years
Lease, tacit renewal period			2 years
Lease, break clause period			1 year
Decrease in lease liabilities through modification of term		€ 622
Lease facilities, Boston
Disclosure Of Lease Liabilities [Line Items]
Lease, duration period	2 years
Lease, extension period	2 years
Lease facilities
Disclosure Of Lease Liabilities [Line Items]
Lease liability, percentage of total				93.00%	97.00%	92.00%

Basis of preparation (Details) € in Thousands, $ in Millions						1 Months Ended		6 Months Ended	12 Months Ended			121 Months Ended
	Mar. 28, 2024 EUR (€)	Oct. 24, 2023 EUR (€)	Oct. 24, 2023 USD ($)	Aug. 22, 2023 EUR (€)	Sep. 02, 2022 EUR (€)	Oct. 31, 2023 EUR (€)	Feb. 28, 2023 EUR (€)	Dec. 31, 2024 EUR (€)	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)	Dec. 31, 2023 EUR (€)
Disclosure of non-adjusting events after reporting period [line items]
Net loss for the period									€ (147,740)	€ (60,740)	€ (42,452)
Capital increases		€ 223,300	$ 235.8						353,377	46,231	69,683	€ 557,200
Proceeds from borrowings												125,000
Proceeds from research tax credit									4,476	4,204		31,100
Net proceeds from sale of royalty certificate					€ 2,931				0	2,931	0	2,900
Other investments									€ 9,050	€ 0	€ 0	9,050
BPI
Disclosure of non-adjusting events after reporting period [line items]
Proceeds from government grants												13,500
Proceeds from conditional advances												€ 6,600
Registered direct offering
Disclosure of non-adjusting events after reporting period [line items]
Capital increases						€ 223,300	€ 130,000
Major revenue transactions \| Forecast
Disclosure of non-adjusting events after reporting period [line items]
Proceeds from research tax credit								€ 4,493
Kreos / Claret convertible notes (OCABSA)
Disclosure of non-adjusting events after reporting period [line items]
Proceeds from borrowings				€ 25,000
Kreos & Claret financing, tranche B \| Major debt transactions
Disclosure of non-adjusting events after reporting period [line items]
Proceeds from borrowings	€ 25,000

Accounting principles (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Principles [Abstract]

Statement of compliance

The consolidated financial statements of the Group as of and for the years ended December 31, 2021, 2022 and 2023 have been

prepared in accordance with both International Financial Reporting Standards (“IFRS”) as issued by the International Accounting

Standard Board (“IASB”) and IFRS as adopted by the European Union (“EU”) regulation n°1606/2002 of July 19, 2002. The term

“IFRS” refers collectively to International Accounting Standards (“IAS”) and IFRS as well as the interpretations issued by the

Standing Interpretations Committee (“SIC”) and the International Financial Reporting Interpretations Standards Committee (“IFRS

IC”), whose application is mandatory for the year ended December 31, 2023.

Going concern

The Group has incurred substantial operating losses since inception and expects to continue to incur significant operating losses for the

foreseeable future and may never become profitable. For the year ended December 31, 2023, the Group had a net loss of €147.7

million.

Since inception, the Group has financed its operations through the issuance of ordinary shares with gross aggregate proceeds of

€557.2 million, of which €130 million of gross proceeds were from offerings of its ordinary shares on Euronext Paris in February 2023

and €223.3 million of gross proceeds were from its offering of ordinary shares in the form of American Depository Shares ("ADS") on

the Nasdaq Global Market as well as ordinary shares in Europe (including France) and countries outside of the United States in a

private placement in October 2023, bank borrowings and structured loans for €125.0 million, reimbursements of Research Tax Credits

(Crédit d’Impôt Recherche (“CIR”)) in an aggregate amount of €31.1 million, subsidies received from Banque Publique

d’Investissement (“Bpifrance”) (including €13.5 million of subsidies and €6.6 million of conditional advances) and royalty certificates

in an amount of €2.9 million.

As a result of (a) the Group’s existing cash and cash equivalents of €251.9 million and other short term investments of €9.0 million as

of December 31, 2023 and (b) the drawdown of the second tranche of the Kreos / Claret Financing amounting to €25 million in gross

proceeds and announced on March 28, 2024, and (c) the expected reimbursement of the CIR from 2023 in the second half of 2024

amounting to €4.5 million, the Group expects, as of the date of issuance of these financial statements, to be able to fund its forecasted

cash flow requirements into the fourth quarter of 2025. This takes into account management's assumption that R&D expenditure will

be substantially increased in 2024 driven by the progression of the Phase 3 clinical trials of obefazimod in UC and the initiation of the

Phase 2b clinical trials for CD. Under these assumptions and based on the Group's current clinical plan, the Group would have

sufficient funds to finance its operations through the announcement of its top-line data from the Phase 3 ABTECT-1 and ABTECT-2

induction trials for UC.

Based on the above, these financial statements have been prepared on a going concern basis.

Impact of the Ukraine/Russia Hostilities on the Group

In February 2022, Russia invaded Ukraine. The conflict has already had major implications for the global economy and the rate of

inflation, particularly in relation to the supply of energy, raw materials and food products. It has also caused intense volatility on the

financial markets, something that is still ongoing at the reporting date and has pushed down stock market prices around the world.

Given these developments, the Group has decided not to include Russia and Belarus in its global Phase 3 program for obefazimod in

UC. However, the global scale of this conflict cannot be predicted at this stage. The Group, therefore, cannot rule out an adverse

impact of this conflict on its business, including in terms of access to raw materials, logistics, the performance of clinical studies and

in relation to any future financing the Group may seek.

The long-term safety and efficacy extension of the Phase 2b maintenance trial of obefazimod in moderately to severely active UC is

the Group’s only clinical trial with patients currently enrolled in Ukraine. The Phase 2b 12-month assessment was carried out in all

the Ukrainian patients before the war broke out and these patients are therefore included in the one-year maintenance results that were

reported on April 6, 2022. Ukrainian patients who completed the two-year Phase 2b maintenance trial have been transitioned to the

long-term safety and efficacy trial that is still on-going. None of these sites are located in the Crimea Region of Ukraine, the so-called

Donetsk People’s Republic, or the so-called Luhansk People’s Republic. The Group is also evaluating the possibility to include a few

Ukrainian sites in the western part of Ukraine in the ABTECT Phase 3 clinical trials.

Together with its CROs, the Group is making considerable efforts to ensure the follow-up of patients who are unable to come to the

study centers. Monitoring takes place through a remote monitoring system that was established and used successfully during the

COVID-19 pandemic.

New, revised or amended Standards and Interpretations

The Group applied the following amendments to IFRS that are effective as of December 31, 2023:

•Amendments to IAS 1 Presentation of Financial Statements and IFRS Practice Statement 2 – Disclosure of Accounting

Policies;

•Amendments to IAS 8 – Definition of Accounting Estimates;

•Amendments to IAS 12 – Deferred Tax related to Assets and Liabilities arising from a Single Transaction;

•Amendments to IAS 12 – International Tax Reform—Pillar Two Model Rules;

•IFRS 17 – Insurance Contracts and related amendments.

The Group assessed the impacts resulting from the application of these issued accounting pronouncements and concluded that impacts

are not material.

New standards, amendments and interpretations issued by IASB but not yet mandatory for financial years starting from January 1, 2023

New standards, amendments and interpretations issued by IASB but not yet mandatory for financial years starting from January 1,

2023

The Group did not elect for early application of the following new standards, amendments and interpretations, which were issued but

not mandatory as of December 31, 2023:

•Amendments to IAS 1 Presentation of Financial Statements – Classification of Liabilities as Current or Non-current, and

Non-current Liabilities with Covenants, whose application is for annual reporting periods beginning on or after January

1, 2024; and

•Amendments to IAS 7 Statement of Cash Flows and IFRS 7 Financial Instruments: Disclosures – Supplier Finance

Agreements, whose application is for annual reporting periods beginning on or after January 1, 2024 (not yet approved

by the EU); and

•Amendments to IFRS 16 Leases: Lease Liability in a Sale and Leaseback, whose application is for annual reporting

periods beginning on or after January 1, 2024; and

•Amendments to IAS 21 The Effects of Changes in Foreign Exchange Rates – Lack of Exchangeability whose application

is for annual reporting periods beginning on or after January 1, 2025 (not yet approved by the UE).

The Group assessed the impacts resulting from the application of these issued accounting pronouncements and concluded that impacts

are not material, with the exception of the amendments to IAS 1, issued in 2020 and 2022, which aim at clarifying the requirements on

determining whether a liability is current or non-current, and require new disclosures for non-current liabilities that are subject to

future covenants. In accordance with these amendments, an entity shall classify a liability as current when it does not have the right at

the end of the reporting period to defer settlement of the liability for at least twelve months after the reporting period.

These amendments can impact liabilities with covenants which breach can render the related liabilities repayable within 12 months.

However, the Group has no such liabilities.

Under the amendments, a settlement of a liability includes transferring an entity's own equity instruments to the counterparty.

Therefore, if a liability has any conversion options that involve a transfer of the entity's own equity instruments, then these generally

affect its classification as current or non-current. As an exception, if these conversion options are recognized as equity under IAS 32,

then they do not affect the current or non-current classification of the liability.

As disclosed in Notes 15.1 and 15.2, the Group has convertible notes (the OCEANE as of December 31, 2021 and 2022 and the

Kreos / Claret OCABSA and the Heights convertible notes as of December 31, 2023, as defined below) that are convertible in

ordinary shares of the Group at any time at the option of the noteholders. In application of the amendments, the Group will no longer

be considered to have an unconditional right to defer the settlements of the OCEANE and the Heights convertible notes due to their

conversion options that are embedded derivatives not recognized as equity components. Consequently, the amendments will lead to

the reclassification of these convertible notes as current liabilities on a retrospective basis. The classification of the Kreos / Claret

OCABSA will not be impacted since they are compound instruments with conversion option and attached OCABSA warrants

recognized as an equity component.

Goodwill

Following initial recognition, goodwill is stated at cost less any accumulated impairment losses (see Note 4.4).

In respect of business combinations prior to January 1, 2020, in accordance with IFRS 1 exemption, goodwill is included on the basis

of its deemed cost, which represents the amount recorded under the prior basis of accounting, French GAAP, (“Previous GAAP”).

Intangible assets