Abivax Announces Acceptance Of Additional Late-Breaking Abstract From The ABTECT Phase 3 Induction Trials To Be Presented At 2025 United European Gastroenterology (UEG) Meeting

• Late Breaking Abstract titled EFFICACY AND SAFETY OF OBEFAZIMOD IN PATIENTS WITH MODERATELY TO SEVERELY ACTIVE ULCERATIVE COLITIS: RESULTS FROM TWO, PHASE 3, RANDOMISED, DOUBLE-BLIND, PLACEBO-CONTROLLED, 8-WEEK INDUCTION TRIALS (ABTECT-1 & 2) to be presented Sunday, October 5 at 5pm CEST
  

PARIS, France – September 29, 2025 – 10:05 PM CEST – Abivax SA (Euronext Paris: FR0012333284 – ABVX / Nasdaq: ABVX) (“Abivax” or the“Company”), a clinical-stage biotechnology company developing innovative therapies to address chronic inflammatory diseases, today announced the presentation of a second late breaking abstract for its lead drug candidate, obefazimod, for the treatment of moderately to severely active ulcerative colitis (UC) at The United European Gastroenterology Congress, taking place October 4-7, 2025, in Berlin, Germany.

"The acceptance of this additional late-breaking abstract underscores the significance of the ABTECT Phase 3 induction trial results which demonstrate the statistically significant and clinically meaningful clinical activity and impressive safety and tolerability profile of obefazimod in patients with moderately to severely active ulcerative colitis during the 8-week induction trials. These findings are crucial steps towards potentially offering a novel, first-in-class oral treatment option for patients who urgently need new therapeutic approaches to achieve and maintain remission," said Fabio Cataldi, MD, Chief Medical Officer of Abivax.

Obefazimod data to be presented:

About Abivax
Abivax is a clinical-stage biotechnology company focused on developing therapeutics that harness the body's natural regulatory mechanisms to stabilize the immune response in patients with chronic inflammatory diseases. Based in France and the United States, Abivax's lead drug candidate, obefazimod (ABX464), is in Phase 3 clinical trials for the treatment of moderately to severely active ulcerative colitis.

Contact:
Patrick Malloy
SVP, Investor Relations
Abivax SA
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FORWARD-LOOKING STATEMENTS

This press release contains forward-looking statements, forecasts and estimates, including those relating to the Company's business. Words such as“anticipate,”“expect,”“potential” and variations of such words and similar expressions are intended to identify forward-looking statements. These forward-looking statements include statements concerning the Company's expectations for the potential therapeutic benefit of obefazimod, and the Company's participation at industry conferences. Although Abivax's management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks, contingencies and uncertainties, many of which are difficult to predict and generally beyond the control of Abivax, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and statements. A description of these risks, contingencies and uncertainties can be found in the documents filed by the Company with the French Autorité des Marchés Financiers pursuant to its legal obligations including its universal registration document (Document d'Enregistrement Universel) and in its Annual Report on Form 20-F filed with the U.S. Securities and Exchange Commission on March 24, 2025 under the caption“Risk Factors.” These risks, contingencies and uncertainties include, among other things, the uncertainties inherent in research and development, future clinical data and analysis, decisions by regulatory authorities, such as the FDA or the EMA, regarding whether and when to approve any drug candidate, as well as their decisions regarding labelling and other matters that could affect the availability or commercial potential of such product candidates, and the availability of funding sufficient for the Company's foreseeable and unforeseeable operating expenses and capital expenditure requirements. Special consideration should be given to the potential hurdles of clinical and pharmaceutical development, including further assessment by the Company and regulatory agencies and IRBs/ethics committees following the assessment of preclinical, pharmacokinetic, carcinogenicity, toxicity, CMC and clinical data. Furthermore, these forward-looking statements, forecasts and estimates are made only as of the date of this press release. Readers are cautioned not to place undue reliance on these forward-looking statements. Abivax disclaims any obligation to update these forward-looking statements, forecasts or estimates to reflect any subsequent changes that the Company becomes aware of, except as required by law. Information about pharmaceutical products (including products currently in development) that is included in this press release is not intended to constitute an advertisement. This press release is for information purposes only, and the information contained herein does not constitute either an offer to sell or the solicitation of an offer to purchase or subscribe for securities of the Company in any jurisdiction. Similarly, it does not give and should not be treated as giving investment advice. It has no connection with the investment objectives, financial situation or specific needs of any recipient. It should not be regarded by recipients as a substitute for exercise of their own judgment. All opinions expressed herein are subject to change without notice. The distribution of this document may be restricted by law in certain jurisdictions. Persons into whose possession this document comes are required to inform themselves about and to observe any such restrictions.

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