Study of Pembrolizumab (MK-3475) Plus Docetaxel Versus Placebo Plus Docetaxel in Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer (mCRPC) (MK-3475-921/KEYNOTE-921)
Summary
The purpose of this study is to assess the efficacy and safety of the combination of pembrolizumab (MK-3475) and docetaxel in the treatment of men with metastatic castration-resistant prostate cancer (mCRPC) who have not received chemotherapy for mCRPC but have progressed on or are intolerant to Next Generation Hormonal Agent (NHA). There are two primary study hypotheses. Hypothesis 1: The combination of pembrolizumab plus docetaxel plus prednisone is superior to placebo plus docetaxel plus prednisone with respect to Overall Survival (OS). Hypothesis 2: The combination of pembrolizumab plus docetaxel plus prednisone is superior to placebo plus docetaxel plus prednisone with respect to Radiographic Progression-free Survival (rPFS) per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as assessed by blinded independent central review.
Timeline
- Start
- 2019-05-02
- Primary completion
- 2022-06-20
- Completion
- 2023-07-18
Outcome
Mixed primary results
registry analysis (superiority test); Pembrolizumab + Docetaxel vs Placebo + Docetaxel; p = 0.1677; Hazard Ratio (HR) 0.92 (95% CI 0.78 to 1.09) NCT03834506 ↗
registry analysis (superiority test); Pembrolizumab + Docetaxel vs Placebo + Docetaxel; p = 0.0335; Hazard Ratio (HR) 0.85 (95% CI 0.71 to 1.01) NCT03834506 ↗
Publications
- Results Petrylak DP, Ratta R, Matsubara N, Korbenfeld E, Gafanov R, Mourey L, Todenhofer T, Gurney H, Kramer G, Bergman AM, Zalewski P, De Santis M, Armstrong AJ, Gerritsen W, Pachynski R, Byun SS, Retz M, Levesque E, McDermott R, Bracarda S, Manneh R, Levartovsky M, Li XT, Schloss C, Poehlein CH, Fizazi K. Pembrolizumab Plus Docetaxel Versus Docetaxel for Previously Treated Metastatic Castration-Resistant Prostate Cancer: The Randomized, Double-Blind, Phase III KEYNOTE-921 Trial. J Clin Oncol. 2025 May 10;43(14):1638-1649. doi: 10.1200/JCO-24-01283. Epub 2025 Mar 5.
- Petrylak DP, Ratta R, Gafanov R, Facchini G, Piulats JM, Kramer G, Flaig TW, Chandana SR, Li B, Burgents J, Fizazi K. KEYNOTE-921: Phase III study of pembrolizumab plus docetaxel for metastatic castration-resistant prostate cancer. Future Oncol. 2021 Sep;17(25):3291-3299. doi: 10.2217/fon-2020-1133. Epub 2021 Jun 8.
Drugs
| Evaluation | Drug | Modality | Dose | Route |
|---|---|---|---|---|
| Subject | Pembrolizumab | Monoclonal antibody | 200 mg | Intravenous |
| Background | Dexamethasone | Small molecule | 8 mg | Oral |
| Background | Docetaxel | Small molecule | 75 mg/m2 | Intravenous |
| Background | Prednisone | Other / unclassified | 5 mg | Oral |