OSE Immunotherapeutics

Earnings Release • Apr 16, 2024

OSE Immunotherapeutics' Global License to Develop a Novel Monoclonal Antibody for the Treatment of Chronic Inflammation Becomes Effective

NANTES, France, April 16, 2024 – OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE), a clinical-stage immunotherapy company, today announced that the Hart-Scott-Rodino waiting period has expired with respect to its global license with AbbVie to develop OSE-230, a monoclonal antibody designed to resolve chronic and severe inflammation, currently in the pre-clinical development stage.

As part of the partnership agreement announced on February 28, 2024, AbbVie received from OSE Immunotherapeutics an exclusive global license and collaboration agreement to develop OSE-230, a monoclonal antibody designed to resolve chronic inflammation.

Under the terms of this agreement, AbbVie will now make an upfront payment of \$48 million to OSE Immunotherapeutics. In addition, OSE Immunotherapeutics will be eligible to receive up to an additional \$665 million in clinical development, regulatory and commercial milestones and potential tiered royalties on global net sales of OSE-230.

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).

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): first positive results in the ongoing Phase 1/2 in solid tumors.
• 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); successful Phase 1 in the US (sponsor Veloxis Pharmaceuticals, Inc.).
• BI 765063 and BI 770371 (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-230 (ChemR23 agonist mAb) developed in partnership with AbbVie in chronic inflammation.

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

• Pro-resolutive mAb platform focused on targeting and advancing inflammation resolution and optimizing the therapeutic potential of targeting Neutrophils and Macrophages in I&I. OSE-230 (licensed to AbbVie) is the first candidate generated by the platform, additional discovery programs ongoing on new pro-resolutive GPCRs.
• Myeloid Checkpoint platform focused on optimizing the therapeutic potential of myeloid cells in IO by targeting immune regulatory receptors expressed by Macrophages and Dendritic cells. BI 765063 and BI 770371 (licensed to Boehringer Ingelheim) are the most advanced candidates generated by the platform. Ongoing additional discovery programs, in particular with positive preclinical results obtained in monotherapy with new anti-CLEC-1 mAbs.
• Cytokine platform focused on leveraging the Cis-Delivery of cytokine in IO and I&I. BiCKI® 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-7v is the most advanced BiCKI® candidate targeting anti-PD1xIL-7. Ongoing additional discovery programs on Cis-Demasking technologies.

Additional information about OSE Immunotherapeutics assets is available on the Company's website: www.oseimmuno.com. Click and follow us on X and LinkedIn

Forward-looking statements

This press release contains express or implied information and statements that might be deemed forward-looking information andstatements 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 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 forward-looking information or statements.

Contacts

Sylvie Détry sylvie.detry@ose-immuno.com

Nicolas Poirier Chief Executive Officer nicolas.poirier@ose-immuno.com French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 6 07 768 283

U.S. Media Contact RooneyPartners LLC Kate Barrette kbarrette@rooneypartners.com +1 212 223 0561