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Adding Pembrolizumab to Docetaxel in Metastatic Castration-Resistant Prostate Cancer

By: Julia Fiederlein Cipriano
Posted: Monday, March 13, 2023

According to Daniel P. Petrylak, MD, of Yale Cancer Center, New Haven, Connecticut, and colleagues, the addition of pembrolizumab to docetaxel did not appear to significantly improve radiographic progression–free or overall survival in patients with metastatic castration-resistant prostate cancer who previously underwent androgen-deprivation therapy. The results of the phase III KEYNOTE-921 trial, which were presented during the 2023 American Society for Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract 19), also revealed no notable increase in treatment-related adverse events with this combination.

A total of 1,030 patients were randomly assigned in a 1:1 ratio to receive docetaxel and prednisone in combination with either pembrolizumab or a placebo. According to the investigators, the dual primary endpoints of radiographic progression–free (median, 8.6 vs. 8.3 months; hazard ratio [HR] = 0.85; P = .0335) and overall (median, 19.6 vs. 19.0 months; HR = 0.92; P = .1677) survival were not met with pembrolizumab versus the placebo. The median durations of time to initiation of the first subsequent anticancer therapy were 10.7 and 10.4 months, respectively (HR = 0.86).

A total of 94.6% (grade ≥ 3: 43.2%) of patients treated with pembrolizumab and 94.9% (grade ≥ 3: 36.6%) of those who received the placebo reported treatment-related adverse events. Two and seven treatment-related deaths were reported with pembrolizumab and the placebo, respectively. Immune-mediated adverse events and infusion reactions occurred in 23.3% (grade ≥ 3: 6.2%) of patients treated with pembrolizumab and 12.3% (grade ≥ 3: 1.2%) of those who received the placebo; pneumonitis (7.0% vs. 3.1%) and hypothyroidism (6.4% vs. 3.3%) were observed most frequently.

Disclosure: For full disclosures of the study authors, visit

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