(UroToday.com) The European Society of Medical Oncology (ESMO) 2021 annual meeting’s prostate cancer session included a presentation by Dr. Emmanuel S. Antonarakis discussing updated results of KEYNOTE-199 with four years of follow-up assessing pembrolizumab monotherapy for docetaxel-pretreated mCRPC. KEYNOTE-199 is a multi-cohort phase II study to evaluate pembrolizumab in mCRPC with previous analyses of three cohorts of patients (Cohort 1: RECIST-measurable, PD-L1+; Cohort 2: RECIST-measurable, PD-L1−; Cohort 3: bone-predominant irrespective of PD-L1) who were previously treated with a next-generation hormonal agent and docetaxel showing durable antitumor activity and a manageable safety profile with pembrolizumab. At the 2021 ESMO meeting, Dr. Antonarakis provided an updated efficacy and safety data with 4 years of follow-up.