OSE Immunotherapeutics

Regulatory Filings • May 28, 2019

OSE Immunotherapeutics to Present at 5 th Annual Immuno-Oncology: BD&L and Investment Forum Forum to be held in Chicago, IL, on May 31, 2019

Nantes, France, May 28, 2019 - 8:00 a.m. CET - OSE Immunotherapeutics (ISIN: FR0012127173; Mnémo: OSE) today announced that Alexis Peyroles, chief executive officer, will provide a Company update, including recent accomplishments and future plans, at the upcoming 5 th Annual Immuno-Oncology: BD&L and Investment Forum. The Forum is being held on May 31, 2019 in Chicago, in parallel with the international annual American Society of Clinical Oncology (ASCO) meeting.

Details of the presentation:

• Date and Time: May 31, 2019, 10:30 AM Central Time
• Session: Track B
• Location: Waldorf Astoria Chicago Hotel, Faulkner
• Webcast: https://youtu.be/ue1fN\_e4JOo

About the Annual Immuno-Oncology: BD&L and Investment Forum

Taking place on the first day of ASCO, the 5th Annual Immuno-Oncology BD&L and Investment Forum is designed to bring together thought leaders from cancer research institutes, patient advocacy groups, pharma and biotech to facilitate partnering, funding and investment. We expect over 250 delegates and around 30 presentations by listed and private biotechnology companies seeking licensing & investment.

ABOUT OSE Immunotherapeutics

OSE Immunotherapeutics is a clinical-stage biotechnology company focused on developing and partnering therapies to control the immune system for immuno-oncology and autoimmmune diseases. The company has a diversified first-in-class clinical portfolio consisting of several scientific and technological platforms including neoepitopes and agonist or antagonist monoclonal antibodies, all ideally positioned to fight cancer and autoimmune diseases. The most advanced therapeutic-candidate, Tedopi® , is a proprietary combination of 10 neo-epitopes aimed at stimulating T-lymphocytes and is currently in Phase 3 development in non-small cell lung cancer (NSCLC) after checkpoint inhibitor failure (anti PD-1 and anti PD-L1) and in Phase 2 testing in pancreatic cancer in combination with checkpoint inhibitor Opdivo®. FR104 (an anti-CD28 mAb) has successfully completed Phase 1 testing and has potential to treat autoimmune diseases. BI 765063 (OSE-172) (anti-SIRPa monoclonal antibody) is under a license and collaboration agreement with Boehringer Ingelheim ; this checkpoint inhibitor has received CTA from French and Belgian health authorities for a Phase 1 clinical trial in multiple cancer indications. BiCKI® is a bispecific fusion protein platform built on the key backbone component anti-PD-1 (OSE-279) and targeting innovative targets. OSE-127 (monoclonal

antibody targeting the CD127 receptor, the alpha chain of the interleukin-7 receptor) is partnered with Servier under an option agreement up to the completion of a Phase 2 clinical trial planned in autoimmune bowel diseases; in parallel, Servier plans a development in the Sjögren syndrome. OSE-127 is currently under Phase 1 clinical trial.

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Contacts OSE Immunotherapeutics Sylvie Détry Sylvie.detry@ose-immuno.com +33 153 198 757

French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 607 768 283

U.S. Media: LifeSci Public Relations Darren Opland, Ph.D. darren@lifescipublicrelations.com +1 646 627 8387

U.S. and European Investors Chris Maggos chris@lifesciadvisors.com +41 79 367 6254

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 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 Reference Document filed with the AMF on 26 April 2019, including the annual financial report for the fiscal year 2018 , 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.