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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.
SUBMITTER: Yuan Y
PROVIDER: S-EPMC8691850 | biostudies-literature | 2021 Sep
REPOSITORIES: biostudies-literature
Yuan Yuan Y Lee Jin Sun JS Yost Susan E SE Frankel Paul H PH Ruel Christopher C Egelston Colt A CA Guo Weihua W Padam Simran S Tang Aileen A Martinez Norma N Schmolze Daniel D Presant Cary C Ebrahimi Behnam B Yeon Christina C Sedrak Mina M Patel Niki N Portnow Jana J Lee Peter P Mortimer Joanne J
European journal of cancer (Oxford, England : 1990) 20210701
<h4>Background</h4>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<sup>+</sup>) human epidermal growth factor receptor 2 negative (HER2<sup>-</sup>) metastatic breast cancer (MBC).<h4>Patients and methods</h4>Women with stage IV HR<sup>+</sup> HER2<sup>-</sup> MBC were enrolled and treated with palbociclib, pembrolizumab and letro ...[more]