F-star Therapeutics Announces First Patient Dosed in FS222 Phase 1 Clinical Trial

On January 4, 2021 F-star Therapeutics, Inc. (NASDAQ: FSTX), a clinical-stage biopharmaceutical company dedicated to developing next generation immunotherapies to transform the lives of patients with cancer, reported that the first patient has been dosed in its Phase 1 trial evaluating FS222, a potentially best-in-class bispecific antibody targeting CD137 and PD-L1 (Press release, F-star, JAN 4, 2021, View Source [SID1234574525]).

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This multicenter, open-label, first-in-human trial will evaluate the safety, tolerability, and clinical activity of FS222 in adult patients diagnosed with advanced malignancies. The adaptive study design will allow for the early exploration of clinical activity of FS222 in a range of selected solid tumor types that will guide further targeted future clinical development.

Dr. Louis Kayitalire, CMO of F-star said: "There remains a significant opportunity to provide treatments for patients with difficult to treat cancers, and FS222 may offer an option for patients with low levels of PD-L1 expression. Activation of an immune response in these tumor types creates the potential for a best-in-class therapy, both as a monotherapy and, eventually, in combination. With three bispecifics now in the clinic, we believe we are closer than ever to providing treatment options that many patients have been waiting for."

FS222 targets critical tumoral immune-suppressing pathways via PD-L1 checkpoint blockade and has exhibited in preclinical studies important costimulatory effects through potent clustering and activation of CD137, which in turn, synergistically promote T cell activation and enhance cytotoxic T cell responses. In preclinical models, engagement of PD-L1 and CD137 by FS222 induced T cell proliferation and cytokine production associated with significant tumor regression, significantly better than that observed with a combination of CD137 and PD-L1 targeting antibodies.