(UroToday.com) Pembrolizumab monotherapy has demonstrated durable activity in PD-L1-positive metastatic castration-resistant prostate cancer.1, 2 A single-institution phase 2 study (n=28) of pembrolizumab plus enzalutamide in patients whose disease progressed after enzalutamide showed that the treatment combination demonstrated promising efficacy, suggesting that pembrolizumab plus enzalutamide may be a potential treatment option.3 KEYNOTE-199, is an open-label, global, multicohort, phase 2 study comprising five cohorts, which previously showed durable antitumor activity of pembrolizumab monotherapy in patients with mCRPC previously treated with a next-generation hormonal agent and docetaxel (cohorts 1-3).1 At the ESMO 2020 virtual annual meeting, Dr. Aurelius Omlin and colleagues, presented results including time to cytotoxic chemotherapy and time to new anticancer therapy from this multicohort phase 2 study in chemotherapy-naive patients with mCRPC treated with pembrolizumab plus enzalutamide after progression on enzalutamide and who had RECIST-measurable (cohort 4) or bone-predominant nonmeasurable (cohort 5) disease.