OSE Immunotherapeutics Reaffirms Commitment to Holding a Transparent and Serene General Meeting in Compliance with Market Rules

OSE Immunotherapeutics Reaffirms Commitment to Holding a Transparent and Serene General Meeting in Compliance with Market Rules

Nantes, June 20^th, 2025, 7:30 p.m. - OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE), publishes a “Questions and Answers” document for all its shareholders and informs the market of ongoing procedures, in line with its commitment to holding the annual General Meeting with transparency, serene debates, and compliance with market rules.

In line with its continuous information and transparency approach towards shareholders, the Company has published a "Questions and Answers" document, accessible at the following address: , intended to answer the main questions of shareholders regarding recent events.

Nicolas Poirier, CEO of OSE, states: "We have a responsibility to all those who expect seriousness and results from OSE, primarily the patients. We cannot leave the false information communicated to the market unanswered. For example, there is no plan to use venture debt instruments. In response to these unfounded rumors, we have decided to publish this "Questions and Answers" document. An exchange with all shareholders will be organized soon in the same spirit."

Following the declaration of a concerted action and the submission of several resolutions aimed at significantly altering the composition of the Board of Directors by a group of shareholders¹, the Company reminds the market, that it had requested and obtained, by order of the President of the Nantes Commercial Court dated June 10, 2025, the postponement of the General Meeting initially scheduled for June 25, 2025².

The "group of shareholders" notified the Company today of their challenge to this decision, through a request for the retraction of the June 10, 2025 order, with a hearing scheduled for Tuesday, June 24, 2025.

The postponement of the General Meeting to a later date, aims to address the concerns expressed by certain shareholders in this tense context and to ensure that the consultation of its shareholders can take place in a serene democratic framework, ensuring complete and fair information. This general meeting cannot be a stage for attempts to destabilize and spread erroneous information about the Company.

In this regard, OSE Immunotherapeutics has filed a request today with the Nantes Commercial Court, within the framework of an accelerated procedure (known as "fixed date"), for an action against this same group of shareholders. This action concerns the regularity of the declaration of the concerted action, with the aim of ensuring compliance with the principles of transparency governing shareholder democracy ahead of the Company's next General Meeting.

Subject to the evolution of legal proceedings, the Company currently plans to hold the General Meeting on September 30, 2025.

In this context, the Board of Directors reaffirms its commitment in favor of a transparent, responsible and constructive dialogue among all stakeholders. This commitment is reflected in the procedures and actions undertaken by the Company but also by the joint mobilization of the management and the Board of Directors to install a dialogue with the "group of shareholders". A constructive and formal framework for exchange has thus been proposed to move forward together in the interest of the Company and all its shareholders.

ABOUT OSE IMMUNOTHERAPEUTICS

OSE 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: . Follow us on LinkedIn.

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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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