The PSMA-targeting Half-life Extended BiTE Therapy AMG 160 has Potent Antitumor Activity in Preclinical Models of Metastatic Castration-resistant Prostate Cancer.

Abstract

Metastatic castration-resistant prostate cancer (mCRPC) remains a disease with high unmet medical need, as most patients do not achieve durable response with available treatments. Prostate-specific membrane antigen (PSMA) is a compelling target for mCRPC. It is highly expressed by primary and metastatic prostate cancer cells, with increased expression after progression on androgen deprivation therapy. We developed AMG 160, a half-life extended, bispecific T-cell engager immuno-oncology therapy that binds PSMA on prostate cancer cells and cluster of differentiation 3 on T cells for treatment of mCRPC. AMG 160 was evaluated <i>in vitro</i> and in mCRPC xenograft models. AMG 160 tolerability was assessed in nonhuman primates (NHP). AMG 160 activity as monotherapy and in combination with a PSMA-imaging agent, novel hormonal therapy, and immune checkpoint blockade was evaluated. AMG 160 induces potent, specific killing of PSMA-expressing prostate cancer cell lines <i>in vitro</i>, with half-maximal lysis of 6-42 pmol/L. <i>In vivo</i>, AMG 160 administered weekly at 0.2 mg/kg engages T cells administered systemically and promotes regression of established 22Rv-1 mCRPC xenograft tumors. AMG 160 is compatible with the imaging agent gallium 68-labeled PSMA-11, and shows enhanced cytotoxic activity when combined with enzalutamide or an anti-programmed death-1 antibody. AMG 160 exhibits an extended half-life and has an acceptable safety profile in NHPs. The preclinical characterization of AMG 160 highlights its potent antitumor activity <i>in vitro</i> and <i>in vivo</i>, and its potential for use with known diagnostic or therapeutic agents in mCRPC. These data support the ongoing clinical evaluation of AMG 160 in patients with mCRPC.<i>See related commentary by Kamat et al., p. 2675</i>.