OSE Immunotherapeutics to host a KOL webcast dedicated to lusvertikimab on September 2, 2026

NANTES, France, August 28, 2026 – 7:30am CET - OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) (the "Company"), today announced that the Company will host a webcast with international experts in Inflammatory Bowel Diseases (IBD) to discuss its lead asset lusvertikimab on September 2, 2026, at noon ET (6pm CET).

The discussion will focus on IL-7R biology, promising results from the CoTiKis Phase 2 clinical trial in Ulcerative Colitis, future development plans in Chronic Pouchitis and will conclude with questions from the audience.

Invited experts are Laurent Peyrin-Biroulet, MD, PhD, (Nancy University Hospital, France) and Maia Kayal, MD, MS, (Icahn School of Medicine at Mount Sinai, New York). They will be joined by Marc Le Bozec, Chief Executive Officer and Aurore Morello, PhD, Chief Scientific Officer, OSE Immunotherapeutics.

KOL Webcast on Wednesday, September 2, 2026

6pm CET / noon ET

Live in English with optional French subtitles

Link to Webcast:
https://ose-immunotherapeutics.engagestream.euronext.com/2026-09-02-lusvertikimab

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 listed on Euronext. Additional information about OSE Immunotherapeutics assets is available on the Company’s website: www.ose-immuno.com. Follow us on LinkedIn.

Contacts

OSE Immunotherapeutics: investors@ose-immuno.com

FP2COM (Media Relations): Florence Portejoie: 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’ 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.