Phase II trial of pembrolizumab and epacadostat in recurrent clear cell carcinoma of the ovary: An NRG oncology study GY016

Lilian T. Gien, Danielle M. Enserro, Matthew S. Block, Steven Waggoner, Linda R. Duska, Andrea E. Wahner-Hendrickson, Premal H. Thaker, Floor Backes, Michael Kidd, Carolyn Y. Muller, Paul A. DiSilvestro, Allan Covens, David M. Gershenson, Kathleen N. Moore, Carol Aghajanian, Robert L. Coleman

Research output: Contribution to journalArticlepeer-review


Introduction: Early reports of PD-1 inhibition in ovarian clear cell carcinomas (OCCC) demonstrate promising response. We evaluated the combination of pembrolizumab and IDO-1 inhibitor epacadostat in patients with recurrent OCCC. Methods: This single arm, two-stage, phase 2 trial included those with measurable disease and 1–3 prior regimens. Patients received intravenous pembrolizumab 200 mg every 3 weeks and oral epacadostat 100 mg twice a day. Primary endpoint was overall response rate (ORR), secondary endpoints were toxicity, progression-free survival (PFS) and overall survival (OS). The study was powered to detect an absolute 25% increase in response (15% to 40%). Results: Between September 28, 2018 and April 10, 2019, 14 patients enrolled at first stage. Rate of accrual was 2.3 patients per month. Median age was 65 years (44–89), 10 (71.4%) had ≥2 prior regimens. ORR was 21% (95% CI 5–51%) within 7 months of study entry with 3 partial responses, and 4 had stable disease (disease control rate 50%). Median PFS was 4.8 months (95% CI: 1.9–9.6), OS 18.9 months (95% CI: 1.9-NR). Most common grade ≥ 3 adverse events were electrolyte abnormalities and gastrointestinal pain, nausea, vomiting, bowel obstruction. In July 2019, the study reached the pre-specified criteria to re-open to second stage; however, the study closed prematurely in February 2021 due to insufficient drug supply. Conclusions: Pembrolizumab and epacadostat demonstrated an ORR of 21% in this small cohort of recurrent OCCC. The rapid rate of accrual highlights the enthusiasm and need for therapeutic studies in patients with OCCC.

Original languageEnglish
Pages (from-to)61-68
Number of pages8
JournalGynecologic oncology
StatePublished - Jul 2024


  • Clear cell
  • IDO1
  • Ovarian
  • PD-1
  • Pembrolizumab


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