OSE Immunotherapeutics Presents First Positive Clinical Results With its anti-PD1 OSE-279 in Advanced Solid Tumors

On October 16, 2023 OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) reported the first Phase 1/2 positive clinical results with high affinity anti-PD1 monoclonal antibody OSE-279 in advanced solid tumors at the AACR (Free AACR Whitepaper)-NCI-EORTC AACR-NCI-EORTC (Free AACR-NCI-EORTC Whitepaper) International Conference on Molecular Targets and Cancer Therapeutics (EORTC-NCI-AACR) (Free ASGCT Whitepaper) (Free EORTC-NCI-AACR Whitepaper), held in Boston, MA (October 11 – 15, 2023 – Abstract number 35371, Poster C063) (Press release, OSE Immunotherapeutics, OCT 16, 2023, View Source [SID1234636046]).

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Silvia Comis, Head of Clinical Development and Regulatory Affairs of OSE Immunotherapeutics, comments: "These first efficacy and safety positive results from clinical Phase 1/2 assessing the therapeutic potential of our proprietary anti-PD1 monoclonal antibody OSE-279 in advanced solid tumors are very promising. These results encourage further clinical development of OSE-279 in the future as a monotherapy treatment in pre-identified cancer niche indications, with still high unmet medical needs. This product will also be available for combination with other OSE drug candidates or with external assets opening new potential partnerships."

The communication reported on the first positive results from the Phase 1/2 clinical trial evaluating OSE-279 monotherapy in patients with advanced solid tumors, with no therapeutic option available. These data have shown a manageable safety profile with preliminary signs of efficacy in the first 13 patients included with 8 tumor types and treated by a dose of 100 and 300 mg every 3 weeks (q3w) or 600 mg every 6 weeks (q6w). One confirmed partial response in a hepatocellular carcinoma patient (-81% tumor shrinkage) after a single dose of OSE-279 300 mg and 2 yet unconfirmed partial responses in anal squamous cell carcinoma (-46% tumor shrinkage) and undifferentiated pleomorphic sarcoma (-33% tumor shrinkage) with OSE-279 600 mg, were reported out of 11 patients with at least one post baseline tumor assessment. Furthermore, stable disease longer than 16 weeks was observed in 3 patients (Disease Control Rate: 55%). Pharmacokinetic profile showed good exposure and dose-proportionality and both pharmacokinetic and pharmacodynamic profiles were consistent with modelling. Receptor occupancy was maintained and within the boundaries of simulation. A Phase 2 dose (RP2D) of 300 mg was recommended every 3 weeks and 600 mg appears to be a good candidate for the RP2D every 6 weeks.

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. OSE-279 is also the key anti-PD1 backbone component of OSE’s bifunctional checkpoint inhibitor BiCKI platform that is targeting PD1 and other new immune targets.

The first-in-human open label Phase 1/2 dose escalation and expansion study 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 rates. Secondary objectives include assessment of OSE-279’s antitumor activity, evaluation of the safety profile, pharmacokinetic and receptor occupancy or pharmacodynamic profile (NCT05751798).