anti-STEAP1 antibody-drug conjugate ADRX-0405

An antibody-drug conjugate (ADC) composed of a humanized immunoglobulin G1 (IgG1) monoclonal antibody targeting the tumor-associated antigen (TAA) six transmembrane epithelial antigen of the prostate 1 (STEAP1) conjugated, through a protease-cleavable linker, to a topoisomerase 1 (TOP1) inhibitor payload, with potential antineoplastic activity. Upon administration of anti-STEAP1 ADC ADRX-0405, the antibody moiety targets and binds to STEAP1 expressed on tumor cells. Following receptor internalization and linker cleavage, the TOP1 inhibitor targets and inhibits the activity of DNA topoisomerase 1, thereby inhibiting DNA replication and resulting in cell cycle arrest and tumor cell apoptosis of STEAP1-overexpressing tumor cells. STEAP1 is overexpressed in a variety of cancers, including prostate cancer, while its expression in normal healthy tissue is limited.