Half-Year Report on Liquidity Contract with Invest Securities NANTES, France – January 20, 2026, 6:00pm CET – Under the liquidity contract entrusted by OSE Immunotherapeutics to Invest Securities, the following resources were available in the liquidity account as of December 31, 2025: 40,086 shares €413,431.33 in cash Over the period from 01/07/2025 to 31/12/2025: Number of executions on buy side: 926Number of executions on sell side: 1,019Traded volume on buy side: 169,447 shares for €993,349.58Traded volume on sell side: 157,153 shares for €948,518.44 As a reminder, in the last half-year report as of June 30, 2025, the following resources were available in the liquidity account: 27,792 shares€454,733.83 in cash As a reminder, at the time of the implementation of the liquidity contract on April 25, 2015, the following resources were available in the liquidity account: 0 shares€300,000 in cash ABOUT OSE IMMUNOTHERAPEUTICSOSE Immunotherapeutics is a biotech company dedicated to developing first-in-class assets in immuno-oncology (IO) and immuno-inflammation (I&I) that address the unmet patient needs of today and tomorrow. We partner with leading academic institutions and biopharmaceutical companies in our efforts to develop and bring to the market transformative medicines for people with serious diseases. OSE Immunotherapeutics is based between Nantes and Paris and is quoted on Euronext. Additional information about OSE Immunotherapeutics assets is available on the Company’s website: www.ose-immuno.com. Click and follow us on LinkedIn. Contacts OSE Immunotherapeutics: Fiona Olivier I fiona.olivier@ose-immuno.com FP2COM: Florence Portejoie I fportejoie@fp2com.fr I +33 6 07 768 283 Forward-looking statements This press release contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSE Immunotherapeutics. They do not constitute historical facts. These information and statements include financial projections that are based upon certain assumptions and assessments made by OSE Immunotherapeutics’ management considering its experience and its perception of historical trends, current economic and industry conditions, expected future developments and other factors they believe to be appropriate. These forward-looking statements include statements typically using conditional and containing verbs such as “expect”, “anticipate”, “believe”, “target”, “plan”, or “estimate”, their declensions and conjugations and words of similar import. Although the OSE Immunotherapeutics management believes that the forward-looking statements and information are reasonable, the OSE Immunotherapeutics’ shareholders and other investors are cautioned that the completion of such expectations is by nature subject to various risks, known or not, and uncertainties which are difficult to predict and generally beyond the control of OSE Immunotherapeutics. These risks could cause actual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. These risks include those discussed or identified in the public filings made by OSE Immunotherapeutics with the AMF. Such forward-looking statements are not guarantees of future performance. This press release includes only summary information and should be read with the OSE Immunotherapeutics Universal Registration Document filed with the AMF on April 30, 2025, including the annual financial report for the fiscal year 2024, available on the OSE Immunotherapeutics’ website. Other than as required by applicable law, OSE Immunotherapeutics issues this press release at the date hereof and does not undertake any obligation to update or revise the forward-looking information or statements.
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