2559056-68-5

Biological Activity: Xaluritamig (AMG-509) is a bispecific T cell engager and cytolytic agent with a K_d of 27.6 nM for human CD3ε. Xaluritamig binds to CD3ε via an anti-CD3 single-chain variable fragment (scFv) domain, and to STEAP1 via a bispecific anti-STEAP1 antigen-binding fragment (Fab) domain, thereby recruiting and activating T cells and forming a bridge between T cells and STEAP1-expressing cancer cells. Xaluritamig induces T cell-mediated redirected cytotoxicity, tumor cell lysis, cytokine release, CD8⁺ T cell activation and expansion, as well as tumor stasis or regression. Xaluritamig contains an Fc domain with no effector function, which prolongs serum half-life, exhibits only minimal activity against cells with low STEAP1 expression and normal cells, and shows extremely low target-related off-tumor toxicity in cynomolgus monkeys. Xaluritamig is used in STEAP1×CD3 XmAb 2+1 immunotherapy and in research on metastatic castration-resistant prostate cancer and Ewing sarcoma^[1][2][3].