STEAP1 and neoplasm: Importantly, STEAP1 has low levels of expression in non-neoplastic tissues, making it an ideal target for PCa therapy.49,65–67 Preclinical studies demonstrated AMG509-induced T-cell mediated lysis of STEAP1 expressing cancer cells in various xenograft tumor models.68 Results from an ongoing phase I trial of AMG509 (NCT04221542) reporting data from 97 subjects with mCRPC are highly encouraging.