FPA154

FPA154 is a novel tetravalent anti-GITR agonist antibody developed by Five Prime Therapeutics in collaboration with Inhibrx for immuno-oncology applications. It features a unique design with four GITR binding sites, distinguishing it from conventional bivalent GITR agonist antibodies, and promotes antitumor immune responses through multiple mechanisms including depletion of GITR-expressing regulatory T cells (Tregs) via antibody-dependent cellular cytotoxicity (ADCC) and GITR agonism that enhances effector T cell activity independent of Fc binding. The program targeted solid tumors but was terminated by Five Prime prior to clinical advancement.