Pembrolizumab with bevacizumab and cyclophosphamide for the treatment of recurrent ovarian clear cell carcinoma: A case series

Introduction Treatment for recurrent ovarian clear cell carcinoma (OCCC) is clinically challenging as response rates to traditional chemotherapy are low, and recurrence rates are high. Immunotherapy has shown promise for this ovarian cancer (OC) subtype, and tumor molecular testing allows for the identification of a patient population that might benefit most from this treatment. We describe the clinical course and somatic genomic testing of 4 patients who received pembrolizumab for recurrent OCCC concurrent with a combination of bevacizumab and/or cyclophosphamide. Methods All patients with OCCC treated with immune checkpoint inhibitors (ICI) within a single health system between 2018 and 2023 (excluding those on clinical trials) were identified via retrospective chart review. Results Four patients were included. The average age at diagnosis was 56.5 years, and the number of prior treatments ranged from 1 to 6. All patients received pembrolizumab combined with either bevacizumab and/or cyclophosphamide. All patients (n = 3) who received pembrolizumab and bevacizumab experienced a partial response. Responses were durable, ranging from 6 to 15 months. Somatic genomic testing results demonstrated microsatellite stability and low tumor mutational burden in all patient tumors, and 3 had AT-Rich Interaction Domain 1A gene (ARID1A) mutations. Notably, two patients had treatment-limiting toxicities, one with presumed immune-mediated grade 2 myocarditis, and another with grade 5 hepatitis. Conclusions Pembrolizumab, combined with bevacizumab and cyclophosphamide, is a promising treatment option for patients with recurrent OCCC, though careful risk assessment and counseling regarding toxicities is necessary to maximize the safety and efficacy of this treatment regimen. Prospective studies are needed for validation.