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Cancer research

Pembrolizumab Plus Enzalutamide Combo Fails to Improve Efficacy in Metastatic Prostate Cancer Patients

Strategic Insights

— 1 min read

Researchers at Oregon Health & Science University (OHSU) have conducted a Phase III clinical trial to evaluate the efficacy of pembrolizumab added to enzalutamide in patients with chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC). The study, KEYNOTE-641, involved 615 participants and showed that the combination of pembrolizumab and enzalutamide did not improve efficacy outcomes compared to enzalutamide alone. The study also observed additional toxicity with the combination regimen. The findings suggest that patients with mCRPC should not be treated with pembrolizumab plus enzalutamide as a first-line treatment.

Key Takeaways:

  • The Phase III KEYNOTE-641 study evaluated the efficacy of pembrolizumab plus enzalutamide versus placebo plus enzalutamide in 615 participants with chemotherapy-naive mCRPC.
  • The study showed that the combination of pembrolizumab and enzalutamide did not improve efficacy outcomes compared to enzalutamide alone.
  • 31.2% of participants with pembrolizumab plus enzalutamide and 10.8% with placebo plus enzalutamide experienced one or more treatment-related adverse events.
  • 71 participants (11.5%) and 21 participants (3.4%) discontinued study treatment due to treatment-related adverse events.
  • The study concluded that additional toxicity was observed with the combination regimen.
  • The research has been peer-reviewed and published in the Annals of Oncology.
  • Financial support for the research came from Merck Sharp Dohme LLC.
  • The study authors include J. N. Graff, M. Burotto, P. C. Fong, and others.

Statistics:

  • 192 participants (31.2%) with pembrolizumab plus enzalutamide experienced one or more treatment-related adverse events.
  • 67 participants (10.8%) with placebo plus enzalutamide experienced one or more treatment-related adverse events.
  • 71 participants (11.5%) with pembrolizumab plus enzalutamide discontinued study treatment due to treatment-related adverse events.
  • 21 participants (3.4%) with placebo plus enzalutamide discontinued study treatment due to treatment-related adverse events.

Sources:

  • NewsRx. New Prostate Cancer Study Findings Recently Were Reported by Researchers at Oregon Health & Science University (OHSU) (Pembrolizumab Plus Enzalutamide Versus Placebo Plus Enzalutamide for Chemotherapy-naive Metastatic Castration-resistant ...). Immunotherapy Weekly. August 20, 2025; p 1847.
  • Pembrolizumab Plus Enzalutamide Versus Placebo Plus Enzalutamide for Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer: the Randomized, Double-blind, Phase Iii Keynote-641 Study. Annals of Oncology, 2025;36(8):976-987.

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