641TiP Phase Ib/II trial of pembrolizumab (pembro) + vibostolimab combination therapy in patients (Pts) with adenocarcinoma metastatic castration-resistant prostate cancer (mCRPC) or treatment-emergent neuroendocrine mCRPC (t-NE): KEYNOTE-365 cohorts G and H

Abstract

Treatment options are limited for pts with mCRPC that progresses with NHAs or docetaxel, and outcomes are poor for the ∼20% of pts who develop t-NE. Pembro showed antitumor activity as monotherapy in docetaxel-pretreated pts with adenocarcinoma mCRPC in the phase II KEYNOTE-199 trial and in combination with olaparib in cohort A of the phase III KEYNOTE-365 trial. The TIGIT inhibitor vibostolimab showed antitumor activity in preclinical tumor models. Combining PD-1 and TIGIT inhibition might have enhanced benefit in adenocarcinoma mCRPC and t-NE versus monotherapy.