KEYNOTE-641: a Phase III study of pembrolizumab plus enzalutamide for metastatic castration-resistant prostate cancer.

Current treatment options for men with metastatic castration-resistant prostate cancer (mCRPC) are noncurative, and median survival upon development of mCRPC is approximately 3 years. The novel hormonal agent enzalutamide has an established role in the mCRPC treatment paradigm, and emerging evidence suggests potential synergism with enzalutamide and the PD-1 inhibitor pembrolizumab in men with mCRPC. Here, we describe the design and rationale for the multicenter, randomized, double-blind, Phase III KEYNOTE-641 study, which will be conducted to compare the efficacy and safety of pembrolizumab plus enzalutamide with that of enzalutamide plus placebo in mCRPC.