Is Pembrolizumab Monotherapy of Benefit in Previously Treated Advanced Clear Cell Gynecologic Cancer?

By: Julia Cipriano, MS
Posted: Monday, May 5, 2025

Pembrolizumab showed clinical benefit in a predominantly mismatch repair–proficient population of patients with previously treated advanced clear cell gynecologic cancer, based on the results of the multicenter phase II PEACOCC trial published in JAMA Oncology. According to Rebecca Kristeleit, MD, PhD, of Guy’s and St Thomas’ National Health Service (NHS) Foundation Trust and Comprehensive Cancer Centre, King’s College London, and colleagues, monotherapy with this PD-1 inhibitor also appeared to be tolerable.  

“Clear cell gynecologic cancer represents a disease subtype where there is significant unmet need, and efforts to identify effective therapies are required,” the investigators remarked. “PEACOCC is the only study examining pembrolizumab monotherapy in clear cell gynecologic cancer to date.”  

A total of 48 patients with PD-1 inhibitor–naive disease (ovarian: 85%; endometrial: 13%; cervical: 2%) who experienced radiologic progression after one or more prior courses of chemotherapy were administered 200 mg of intravenous pembrolizumab every 21 days up to 2 years. Those treated with 35 cycles of pembrolizumab were eligible for retreatment at the time of disease progression. 

The investigators reported grade 3 treatment-related adverse events in 19% of patients; no grade 4 or 5 toxicities were documented. Nearly all patients (98%) had mismatch repair–proficient tumors. The 12-week progression-free survival rate was 42%, and the best objective response rate was 25% (partial responders: n = 12). The median durations of progression-free and overall survival were 2.7 and 14.8 months, respectively, after a median follow-up of 46.9 months. 

“Clinical outcomes are superior to historical data for current standard-of-care chemotherapy, and translational research to identify those patients who benefit most is underway,” the investigators concluded. “Further evaluation of anti–PD-1 monotherapy or PD-1 inhibitor combinations in randomized clinical trials is justified for this poor-prognosis gynecologic cancer population.” 

Disclosure: For full disclosures of the study authors, visit jamanetwork.com.  

JAMA Oncology

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