PVZB3001

PVZB3001 is a **bisisothiourea derivative** identified as a potent, dual inhibitor of both **indoleamine 2,3-dioxygenase 1 (IDO1)** and **tryptophan 2,3-dioxygenase (TDO)**—two heme-containing enzymes in the tryptophan-kynurenine pathway that mediate immunosuppression in a range of tumor types. PVZB3001 inhibits kynurenine production in tumor cells (A172 and A431) stimulated with interferon-γ (IFN-γ), with **IC50** values in the submicromolar range for both IDO1 and TDO. The dual inhibition of these enzymes by PVZB3001 leads to reduced kynurenine-mediated suppression of immune effector cells—including natural killer (NK) cells—potentially restoring anti-tumor immune responses. In preclinical models, PVZB3001 demonstrated the ability to suppress tumor growth and modulate the kynurenine/tryptophan ratio when administered orally. It represents a lead compound for immunotherapeutic development as a small-molecule immune checkpoint modulator targeting tryptophan metabolism[1][3].