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Yuan Y, Lee J, Yost SE, Frankel PH, Ruel C, Egelston CA, Guo W, Padam S, Tang A, Martinez N, Schmolze D, Presant C, Ebrahimi B, Yeon C, Sedrak M, Patel N, Portnow J, Lee P, Mortimer J. Phase I/II trial of palbociclib, pembrolizumab and letrozole in patients with hormone receptor-positive metastatic breast cancer. Eur J Cancer 2021; 154:11-20. [PMID: 34217908 PMCID: PMC8691850 DOI: 10.1016/j.ejca.2021.05.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/11/2021] [Accepted: 05/24/2021] [Indexed: 01/15/2023]
Abstract
BACKGROUND CDK4/6 inhibitors modulate immune response in breast cancer. This phase I/II trial was designed to test the safety and efficacy of palbociclib, pembrolizumab and letrozole in women with hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (MBC). PATIENTS AND METHODS Women with stage IV HR+ HER2- MBC were enrolled and treated with palbociclib, pembrolizumab and letrozole. Primary end-points were safety, tolerability and efficacy. RESULTS Between November 2016 and July 2020, 23 patients were enrolled with 20 evaluable for response, including 4 patients in cohort 1 and 16 patients in cohort 2. Cohort 1 median age was 48 years (33-70) and cohort 2 median age was 55 (37-75). Cohort 1 closed early due to limited accrual. Grade III-IV adverse events were neutropenia (83%), leucopaenia (65%), thrombocytopenia (17%) and elevated liver enzymes (17%). In cohort 1, 50% achieved a partial response (PR) and 50% had stable disease (SD). In cohort 2, 31% achieved complete response (CR), 25% had PR and 31% had SD by Response Evaluation Criteria in Solid Tumours version 1.1. Median progression-free survival was 25.2 months (95% confidence interval [CI] 5.3, not reached) and median overall survival was 36.9 months (95% CI 36.9, not reached) in cohort 2 with a median follow-up of 24.8 months (95% CI 17.1, not reached). A correlative immune biomarker analysis was published separately. CONCLUSION The combination of palbociclib, pembrolizumab and letrozole is well tolerated, and a complete response rate of 31% was identified in HR+ MBC patients who received this combination as front-line therapy. Confirmatory trials are required to better understand the immune-priming effects of CDK4/6 inhibitors.
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Affiliation(s)
- Y. Yuan
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA,Corresponding author: Dr. Yuan Yuan, Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center, 1500 E. Duarte Road, Duarte, CA 91010 USA, Phone: 626-256-4673, Fax: 626-301-8233,
| | - J. Lee
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - S. E. Yost
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - P. H. Frankel
- Department of Biostatistics, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - C. Ruel
- Department of Biostatistics, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - C. A. Egelston
- Department of Immune-Oncology, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - W. Guo
- Department of Immune-Oncology, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - S. Padam
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - A. Tang
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - N. Martinez
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - D. Schmolze
- Department of Pathology, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - C. Presant
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - B. Ebrahimi
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - C. Yeon
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - M. Sedrak
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - N. Patel
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - J. Portnow
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - P. Lee
- Department of Immune-Oncology, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
| | - J. Mortimer
- Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center and Beckman Research Institute, Duarte, CA, USA
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