On February 26, 2024 OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) reported an update on the positive results of OSE-279 in the Phase 1/2 clinical evaluation in advanced solid tumors at the 2024 ESMO (Free ESMO Whitepaper) Targeted Anticancer Therapies Congress (ESMO TAT) held in Paris, France (February 26 – 28, Abstract #368; FPN 30P) (Press release, OSE Immunotherapeutics, FEB 26, 2024, View Source [SID1234640481]).

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Silvia Comis, Head of Clinical Development and Regulatory Affairs of OSE Immunotherapeutics, comments: "We are very pleased to share this positive update on the preliminary efficacy and safety results from a Phase 1/2 study assessing the therapeutic potential of our proprietary high affinity anti-PD1 monoclonal antibody OSE-279 in advanced solid tumors. These new results and additional signal of efficacy with a high anti-tumor response rate in difficult-to-treat patients, highlight the value of OSE-279 as a potential strong anti-PD1 therapy and encourage further clinical development in the future in pre-identified cancer niche indications, with still high unmet medical needs. In parallel to OSE-279 monotherapy development, new cohort testing combinations with other OSE drug candidates, including cancer vaccine, are being explored."

The ESMO (Free ESMO Whitepaper)-TAT communication reported on the positive results from the Phase 1/2 clinical trial (NCT05751798) evaluating OSE-279 monotherapy in patients with advanced solid tumors, with no therapeutic option available.

The updated data show a good pharmacokinetic/pharmacodynamic (PK/PD) and manageable safety profile in line with previous anti-PD1 development and with a high signal of efficacy in the first 20 patients representing 13 different tumor types. Four confirmed ongoing partial responses (PR) with 600 mg every six weeks (q6w), with a response rate of 36%, were reported in patients with anal squamous cell carcinoma, undifferentiated pleomorphic sarcoma, oncocytic thyroid cancer, and alveolar soft part sarcoma. One still ongoing confirmed PR (81% reduction of target lesions) has been observed in a patient with hepatocellular carcinoma after one single dose of OSE-279 300 mg. Five stable diseases (SD) were reported at multiple dose levels. Treatment is ongoing in seven patients. Pharmacokinetic (PK) showed dose-proportionality and favorable exposure. Receptor occupancy (RO) was maintained. At 600 mg q6w, no dose-limiting toxicities (DLTs) were reported in 10 patients. Further to the recommendation of a Phase 2 dose (RP2D) of 300 mg q3w, the dose of 600 mg q6w has been selected as the second RP2D.

OSE-279 is a high affinity humanized anti-PD1 monoclonal antibody blocking both PD-L1 and PD-L2, the ligands of PD1 overexpressed by tumor cells and tumor microenvironment. Overexpression of PD-L1 and PD-L2 on tumor and myeloid cells in the tumor microenvironment is a mechanism of tumor immune escape.

Given the advantages of owning a proprietary and protected high affinity anti-PD1 antagonist antibody, OSE Immunotherapeutics has developed a global intellectual property strategy protecting OSE-279 until at least 2039. This has been achieved through recent grants of patents in the U.S., various European countries, China, Japan, Korea, Australia, and Mexico to date. These patents protect the original antibody sequences of OSE-279 associated with its innovative biological and manufacturing properties.

The first-in-human open label Phase 1/2 dose escalation and expansion study, initiated in December 2022, aims to determine the Maximum Tolerated Dose (MTD) and/or the RP2D of OSE-279 as a monotherapy in advanced solid tumors with two possible administration regimens. Secondary objectives include assessment of OSE-279’s antitumor activity, evaluation of the safety profile, pharmacokinetic and receptor occupancy or pharmacodynamic profile (NCT05751798).