France - OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) presented positive topline results from the Phase 1/2 clinical trial evaluating OSE-279, a high-affinity anti-PD1 monoclonal antibody, in patients with solid tumors , at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics held in Boston (October 11 - 15, 2023, Abstract no. 35371, Poster no. C063).

Silvia Comis, Director of Clinical Development and Regulatory Affairs at OSE Immunotherapeutics, comments : 'These first positive Phase 1/2 clinical efficacy and safety results evaluating the therapeutic potential of our anti-PD1 monoclonal antibody in solid tumors advances are very promising. They are encouraging for the continued clinical development of OSE-279 as a monotherapy in the future in pre-identified niche indications affecting cancers with high medical need. This product could also be explored in combination with other OSE drug candidates or with external active ingredients, opening the way to potential new partnerships.'

The communication concerns the first positive results of the Phase 1/2 clinical trial evaluating OSE-279 as monotherapy in patients with solid tumors, with no available therapeutic option. These data show an acceptable safety profile with first signs of effectiveness in the first 13 patients included, presenting 8 tumor types, treated at doses of 100 and 300 mg every 3 weeks or at a dose of 600 mg every 3 weeks. 6 weeks. Three responses were reported in 11 patients who had at least one post-inclusion tumor assessment: a partial response was confirmed in a patient with hepatocellular carcinoma (81% tumor reduction) after a single dose of 300 mg, and two partial responses (not yet confirmed) observed at the dose of 600 mg: one in an anal squamous cell carcinoma (46% tumor reduction) and the other in an undifferentiated pleomorphic sarcoma (33% tumor reduction). Furthermore, stable disease lasting more than 16 weeks was observed in three other patients (disease control rate: 55%). The pharmacokinetic profile showed good exposure and dose proportionality, the pharmacodynamic (receptor occupancy) and pharmacokinetic profiles were consistent with the modeling. The 300 mg dose is recommended for phase 2 (DRP2) for administration every 3 weeks, and the 600 mg dose appears to be a good option for DRP2 for administration every 6 weeks.

OSE-279 is a high-affinity humanized anti-PD1 monoclonal antibody that blocks both PD-L1 and PD-L2, PD1 ligands overexpressed by tumor cells and the tumor microenvironment. OSE-279 also forms the anti-PD1 backbone of OSE's BiCKI platform of bispecific checkpoint inhibitors targeting PD1 and other novel immunotherapy targets.

This first-in-human study is a phase 1/2, open-label, dose escalation and expansion trial that aims to determine the maximum tolerated dose, and/or the recommended phase 2 dose of OSE-279 as monotherapy. in solid tumors, with two possible administration rates. Secondary objectives include evaluation of antitumor activity, safety profile, pharmacokinetics and receptor occupancy defining the pharmacodynamic profile (NCT05751798).

ABOUT OSE IMMUNOTHERAPEUTICS

OSE Immunotherapeutics is a biotechnology company that develops first-in-class products in immuno-oncology and immuno-inflammation. Its first-in-class clinical portfolio includes: Tedopi (specific T lymphocyte activation immunotherapy against cancer cells, 'off-the-shelf' based on neo-epitopes): the Company's most advanced product; positive results from the Phase 3 trial (Atalante 1) in non-small cell lung cancer (NSCLC) in patients with secondary resistance after failure of a checkpoint inhibitor. Other trials, promoted by clinical groups in oncology, of Tedopi in combination are underway in solid tumors.

OSE-279 (anti-PD1): First positive results from the ongoing Phase 1/2 study in solid tumors. OSE-279 is the basic framework of the BiCKI platform.

OSE-127 - Lusvertikimab (humanized monoclonal antibody antagonist of the IL-7 receptor): Phase 2 in progress in ulcerative colitis (promoter OSE Immunotherapeutics); ongoing preclinical research work in leukemia (OSE Immunotherapeutics).

VEL-101/FR104 (anti-CD28 monoclonal antibody): developed in partnership with Veloxis Pharmaceuticals, Inc. in transplantation; Phase 1/2 underway in kidney transplantation (under the promotion of the University Hospital Center of Nantes); Phase 1 underway in the United States (promoter Veloxis Pharmaceuticals, Inc.).

BI 765063 (anti-SIRP monoclonal antibody on the SIRP/CD-47 axis): developed in partnership with Boehringer Ingelheim (BI) in advanced solid tumors; positive results from Phase 1 of dose escalation in monotherapy and in combination, in particular with the anti-PD1 antibody ezabenlimab; BI-promoted international Phase 1b ongoing in combination with ezabenlimab alone or with other drugs in relapsed or metastatic head and neck cancer and hepatocellular carcinoma.

OSE Immunotherapeutics is developing two patented research platforms whose objective is to deliver first-in-class immunotherapy treatments: BiCKI platform, targeted at immuno-oncology (IO), bispecific fusion protein platform built around a central anti-PD-1 backbone fused with new immunotherapy targets to increase anti-tumor effectiveness. The most advanced candidate is BiCKI-IL-7 which targets anti-PD1xIL-7.

Myeloid platform, which aims to optimize the therapeutic potential of myeloid cells in IO and immuno-inflammation (I&I). OSE-230 (ChemR23 agonist antibody) is the most advanced candidate in this platform; it has the potential to resolve chronic inflammation by restoring the integrity of pathological tissue.

Forward-looking statements

This press release contains, implicitly or expressly, information and statements that may be considered forward-looking regarding OSE Immunotherapeutics. They do not constitute historically proven facts. This information and statements include financial projections based on assumptions or assumptions made by the management of OSE Immunotherapeutics in light of their experience and their perception of historical trends, current economic and industry conditions, future developments and other factors that they consider appropriate.

These forward-looking statements can often be identified by the use of the conditional tense and by the verbs 'expect', 'anticipate', 'believe', 'plan' or 'estimate' and their variations and conjugations as well as by other similar terms. Although the management of OSE Immunotherapeutics believes that these forward-looking statements are reasonable, OSE Immunotherapeutics shareholders and other investors are alerted to the fact that their achievement is inherently subject to numerous known and unknown risks and uncertainties, which are difficult to predict. and outside the control of OSE Immunotherapeutics. These risks may cause actual results and developments to differ materially from those indicated or implied in these forward-looking statements. These risks include in particular those developed or identified in public documents filed by OSE Immunotherapeutics with the AMF. Such forward-looking statements constitute no guarantee of future performance. This press release only includes summary elements and should be read in conjunction with the Universal Registration Document of OSE Immunotherapeutics, registered by the AMF on May 2, 2023, including the 2022 annual financial report, available on the OSE website Immunotherapeutics. OSE Immunotherapeutics undertakes no obligation to update forward-looking information and statements except as required by applicable laws and regulations.

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