CA-170 (CA170) is a first-in-class, orally available, tripeptide small-molecule dual antagonist of VISTA/PD-L1, important negative checkpoint regulators of immune activation.
CA-170 demonstrated dose-dependent enhancement in the proliferation of PD-L1, PD-L2, and VISTA-inhibited T lymphocytes, and exhibited antitumor effects similar to those of antibodies, including tumor shrinkages and prolonged stable disease without adverse effects.
CA170 has excellent oral bioavailability, a relatively short half-life, and it can dose-dependently enhance the proliferation of T lymphocytes due to its ability to inhibit VISTA.
In syngeneic murine tumor models, the antitumor effects of CA170 were similar to VISTA-blocking antibody.
CA170 was well tolerated in phase I clinical trials and is undergoing phase II clinical trials for lung cancer, head and neck/oral cavity cancer, MSI-H positive cancers, and Hodgkin lymphoma.