OSE Immunotherapeutics

Board/Management Information • May 31, 2023

OSE Immunotherapeutics' Board of Directors Proposes the Appointment of Eric Leire, MD, as New Independent Director

Ahead of the General Shareholders' Meeting of June 22, 2023

Nantes, France – May 31, 2023, 6:00 p.m. CET – OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) today announced that the Board of Directors, upon the proposal of the Nomination and Remuneration Committee, has proposed Eric Leire, MD, as an independent Director of the Company. This appointment reflects the Company's willingness to enlarge the Board's skills and expertise and to strengthen its international scope to support its growth.

Moreover, the Board of Directors proposes the appointment of Nicolas Poirier*, Chief Executive Officer of OSE Immunotherapeutics, as director and of Anne-Laure Autret-Cornet, Chief Financial Officer, as director representing the employee shareholders who voted in her favor. The renewal of the term of office of Pr. Brigitte Dréno and Pr. Gérard Tobelem as independent directors is also proposed.

Eric Leire brings a professional international experience, both in the US and in Europe, in biotechnology and in the pharmaceutical industry. He is currently President and Chief Executive Officer of Genflow Biosciences Ltd (listed on LSE:GENF / gene therapy, senescence domain). Previously, he was Chairman and President and Chief Executive Officer of two companies in the US: Enochian Biosciences (listed on Nasdaq ENOB / cell and gene therapy, VIH and cancer) and DanDrit Biotech (listed on OTCQB). He formerly held the position of Marketing manager in the pharmaceutical industry in the US and in Europe (Pfizer, Schering Plough, Boots Pharma). Through his active experience in venture capital funds in the health field at Medwell Capital (Canada) and Biofund Venture (Denmark), he has developed biotech companies financed by investment funds.

Eric Leire is a Medical Doctor (Grenoble University), holder of a postgraduate diploma (DESS) in Health law (Sceaux University). He spent 3 years as a researcher at the Harvard AIDS Institute. He holds an MBA from HEC (ISA) and from Kellogg Graduate School of Management (Chicago). Eric Leire is American and French citizen.

* Nicolas Poirier, previously director representing the employee shareholders, resigned with effect at the General Shareholders' Meeting approving 2022 financial statements, further to his appointment as Chief Executive Officer on October 7, 2022.

ABOUT OSE Immunotherapeutics

OSE Immunotherapeutics is a biotech company dedicated to developing first-in-class assets in immuno-oncology and immuno-inflammation. The Company's current well-balanced first-in-class clinical pipeline includes:

• Tedopi® (immunotherapy activating tumor specific T-cells, off-the-shelf, neoepitope-based): this cancer vaccine is the Company's most advanced product; positive results from the Phase 3 trial (Atalante 1) in Non-Small Cell Lung Cancer patients in secondary resistance after checkpoint inhibitor failure. Other Phase 2 trials, sponsored by clinical oncology groups, of Tedopi® in combination are ongoing in solid tumors.
• OSE-279 (anti-PD1): ongoing Phase 1/2 in solid tumors or lymphomas (first patient included). OSE-279 is the backbone therapy of the BiCKI® platform.
• OSE-127 lusvertikimab (humanized monoclonal antibody antagonist of IL-7 receptor); ongoing Phase 2 in Ulcerative Colitis (sponsor OSE Immunotherapeutics); ongoing preclinical research in leukemia (OSE Immunotherapeutics).

• FR-104/VEL-101 (anti-CD28 monoclonal antibody): developed in partnership with Veloxis Pharmaceuticals, Inc. in transplantation; ongoing Phase 1/2 in renal transplant (sponsor Nantes University Hospital); Phase 1 ongoing in the US (sponsor Veloxis Pharmaceuticals, Inc.).
• OSE-172/BI 765063 (anti-SIRPα monoclonal antibody on CD47/SIRPα pathway) developed in partnership with Boehringer Ingelheim in advanced solid tumors; positive Phase 1 dose escalation results in monotherapy and in combination, in particular with anti-PD-1 antibody ezabenlimab; international Phase 1b ongoing clinical trial in combination with ezabenlimab alone or with other drugs in patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) and hepatocellular carcinoma (HCC).

OSE Immunotherapeutics expects to generate further significant value from its two proprietary drug discovery platforms, which are central to its ambitious goal to deliver next-generation first-in-class immunotherapeutics:

• BiCKI® platform focused on immuno-oncology (IO) is a bispecific fusion protein platform built on the key backbone component of anti-PD1 combined with a new immunotherapy target to increase anti-tumor efficacy. BiCKI-IL-7 is the most advanced BiCKI® candidate targeting anti-PD1xIL-7.
• Myeloid platform focused on optimizing the therapeutic potential of myeloid cells in IO and immuno-inflammation (I&I). OSE-230 (ChemR23 agonist mAb) is the most advanced candidate generated by the platform, with the potential to resolve chronic inflammation by driving affected tissues to tissue integrity.

Additional information about OSE Immunotherapeutics assets is available on the Company's website: www.ose-immuno.com Click and follow us on Twitter and LinkedIn

French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 6 07 76 82 83

Contacts

OSE Immunotherapeutics Sylvie Détry sylvie.detry@ose-immuno.com +33 1 53 198 757

Nicolas Poirier Chief Executive Officer nicolas.poirier@ose-immuno.com +33 6 68 08 85 68

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 in light of 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 forwardlooking 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 May 2, 2023, including the annual financial report for the fiscal year 2022, 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 forwardlooking information or statements.