TH-302 (CAS 918633-87-1) is a hypoxia-activated prodrug comprising a 2-nitroimidazole moiety linked to a brominated isophosphoramide mustard Under severe hypoxic conditions (approximately 0 1% O ) TH-302 undergoes bioreductive activation releasing the cytotoxic alkylating agent Br-IPM selectively within hypoxic tumor microenvironments In vitro studies demonstrate markedly increased cytotoxicity against tumor cell lines under hypoxia with IC50 values ranging from 0 1 to 0 8 M for H460 Caki-1 SK-MEL-5 DU145 and HCT116 cells while IC50 values exceed 40 M in normoxic conditions In H460 xenograft mouse models TH-302 induces dose-dependent tumor growth inhibition without hematological toxicity and increases H2AX-positive cells indicating DNA damage TH-302 is utilized to investigate tumor hypoxia-targeting therapies and mechanisms of selective cytotoxicity