| (Amounts in thousands of euros) | Notes | YEAR ENDED DECEMBER 31, 2021 | YEAR ENDED DECEMBER 31, 2022 | YEAR ENDED DECEMBER 31, 2023 | |
| Cash flows used in operating activities | Net loss for the period | (42,452) | (60,740) | (147,740) | |
| Ajustments for: | Elimination of amortization of intangibles and depreciation of property, plant and equipment | 302 | 485 | 707 | |
| Elimination of Impairment loss of goodwill | 6 | — | 13,632 | — | |
| Elimination of retirement benefit obligations | 16 | 117 | 143 | 109 | |
| Elimination of share-based compensation expenses | 14 | 828 | (1,164) | 8,179 | |
| (-) Net gain on sale of treasury shares | — | (108) | (34) | ||
| Interest expenses and other financial expenses | 21 | 3,561 | 7,028 | 24,827 | |
| Financial income | 21 | — | (288) | (2,953) | |
| Effect of unwinding the discount related to advances | 1,939 | (2) | (355) | ||
| Increase/(decrease) in derivatives and liabilities fair value | 15 | (2,427) | (10,817) | (1,158) | |
| Forgiveness of Covid 19 conditional advances | 17 | (6,348) | — | — | |
| Other | 98 | (100) | 22 | ||
| Cash flows used in operating activities before change in working capital requirements | (44,381) | (51,933) | (118,395) | ||
| Decrease / (increase) in other receivables and other assets | (1,977) | 312 | (14,231) | ||
| Increase / (decrease) in trade payables | 1,141 | (2,388) | 31,757 | ||
| Increase / (decrease) in tax and social security liabilities | 209 | 100 | 3,821 | ||
| Increase / (decrease) in deferred income and other liabilities | (41) | (26) | (81) | ||
| Changes in working capital requirements | (667) | (2,002) | 21,265 | ||
| Cash flows used in operating activities | (45,048) | (53,936) | (97,130) | ||
| Cash flows used in investing activities | Acquisitions of intangible assets | — | (35) | — | |
| Acquisitions of property, plant and equipment | (47) | (288) | (265) | ||
| Advance made to CROs | 10 | — | (12,187) | (1,620) | |
| Payments for the acquisition of Prosynergia, incl. related costs, net of cash acquired (1) | 4.15 & 10 | (2,176) | (2,913) | — | |
| Increase in Deposits and other financial assets | 9 | (9) | (142) | (9,351) | |
| Decrease in Deposits | 9 | — | 218 | 741 | |
| Repayment / (disbursement) of the advance made to the Nice CHU | 10 | (4,000) | 3,302 | — | |
| Interest received | — | 19 | 2,400 | ||
| Cash flows used in investing activities | (6,232) | (12,026) | (8,095) | ||
| Cash flows provided by (used in) financing activities | Capital increases | 13 | 69,683 | 46,231 | 353,377 |
| Transaction costs related to capital increase | 13 | (4,153) | (3,280) | (28,111) | |
| Warrants subscription | — | 3 | 3 | ||
| Repayments of KREOS (2) 1&2 bond loans | 15 | (5,537) | (9,410) | (11,635) | |
| Repayments of convertible loan notes | 15 | — | — | (27,188) | |
| Net proceeds from convertible loan notes | 15 | 24,913 | — | 55,841 | |
| Repayment of PGE | 15 | — | — | (1,250) | |
| Net proceeds from sale of royalty certificate | 15 | — | 2,931 | — | |
| Net proceeds from sale of treasury shares | 15 | — | 143 | 10 | |
| Repayments of conditional advances | 15 | (70) | (90) | (110) | |
| Payments of the lease liabilities | 15 | (249) | (301) | (529) | |
| Interest paid | 15 | (1,908) | (4,015) | (5,279) | |
| Other | — | — | 160 | ||
| Cash flows provided by (used in) financing activities | 82,679 | 32,211 | 335,290 | ||
| Effect of movements in exchange rates on cash held | 11 | — | — | (5,072) | |
| Increase (decrease) in cash and cash equivalents | 31,399 | (33,751) | 224,992 | ||
| Cash and cash equivalents at the beginning of the year | 11 | 29,302 | 60,701 | 26,950 | |
| Cash and cash equivalents at the end of the year | 11 | 60,701 | 26,950 | 251,942 | |
| Increase (decrease) in cash and cash equivalents | 31,399 | (33,751) | 224,992 |
| (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 |
| (In thousands of euros) | DEFERRED TAX ASSETS AND LIABILITIES BY NATURE | AS OF DECEMBER 31, 2021 | AS OF DECEMBER 31, 2022 | AS OF DECEMBER 31, 2023 |
| Retirement benefit obligation | 184 | 152 | 157 | |
| Leases | — | — | 135 | |
| Other financial liabilities | 35 | 198 | 351 | |
| Tax losses carryforward | 61,524 | 77,207 | 114,946 | |
| Other items | — | — | 417 | |
| Deferred tax assets | 61,743 | 77,558 | 116,006 | |
| Subsidies | 85 | 50 | 24 | |
| Leases | — | — | 124 | |
| Other financial liabilities | 590 | 1,377 | 285 | |
| Other items | 5 | — | 10 | |
| Deferred tax liabilities | 680 | 1,427 | 444 | |
| Deferred tax assets, net | 61,063 | 76,130 | 115,562 | |
| Unrecognized deferred tax assets | (61,063) | (76,130) | (115,562) | |
| Total deferred taxes, net recognized in the statement of financial position | — | — | — |
| (In thousands of euros) | Year ended December 31, 2021 | Year ended December 31, 2022 | Year ended December 31, 2023 | % 2022 Change | % 2023 Change |
| Other operating income ............................ | €11,961 | €4,583 | €4,621 | (62)% | 1% |
| Total operating income .................................... | 11,961 | 4,583 | 4,621 | (62)% | 1% |
| Sales and marketing expenses ................... | — | — | (6,431) | — | — |
| Research and development expenses ........ | (47,781) | (48,295) | (103,176) | 1% | 114% |
| General and administrative expenses ....... | (5,580) | (7,492) | (22,390) | 34% | 199% |
| Goodwill impairment loss ......................... | — | (13,632) | — | —% | (100)% |
| Total operating expenses .................................. | (53,361) | (69,419) | (131,997) | 30% | 90% |
| Operating income (loss) ................................... | (41,400) | (64,836) | (127,376) | 57% | 96% |
| Financial expenses .................................... | (3,561) | (7,022) | (27,875) | 97% | 297% |
| Financial income ...................................... | 2,509 | 11,118 | 7,511 | 343% | (32)% |
| Financial income (loss) ..................................... | (1,052) | 4,096 | (20,364) | (489)% | (597)% |
| Net loss before tax ............................................. | (42,452) | (60,740) | (147,740) | 43% | 143% |
| Income Tax ................................................ | — | — | — | — | — |
| Net loss for the period ...................................... | €(42,452) | €(60,740) | €(147,740) | 43% | 143% |
| (amounts in thousands of euros) | YEAR ENDED DECEMBER 31, 2022 | YEAR ENDED DECEMBER 31, 2023 |
| Audit fees | 100 | 1,714 |
| Audit-related fees | — | — |
| Tax fees | — | — |
| All other fees | 740 | 492 |
| Total | 840 | 2,206 |
