KYPS-80

KYPS-80 is a novel small-molecule dual inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO2) currently in preclinical development for cancer immunotherapy. These enzymes are critical components of the kynurenine pathway, which tumors exploit to create an immunosuppressive microenvironment by depleting tryptophan and producing kynurenine. By inhibiting both IDO1 and TDO2, KYPS-80 aims to restore the activity of effector T cells within the tumor. Preclinical studies presented at the AACR 2026 meeting demonstrated that KYPS-80, as a monotherapy and in combination with pembrolizumab, effectively suppressed tumor growth and enhanced CD8+ T cell activation in humanized mouse models of lung adenocarcinoma.