Complete remission of heavily treated ovarian clear cell carcinoma with ARID1A mutations after pembrolizumab and bevacizumab combination therapy: a case report

Background: Patients with ovarian clear cell carcinoma (OCCC) have a poor prognosis because they show low sensitivity to platinum-based chemotherapy. New treatments for refractory OCCC are urgently needed. Case presentation: We present a patient with refractory OCCC in whom conventional chemotherapy failed. Cachexia was induced by the disseminating recurrent tumors. Tumor tissue staining and genomic analysis revealed PD-L1 negativity, a low tumor burden, stable microsatellite instability, and two mutations in ARID1A. The patient was administered pembrolizumab combined with bevacizumab triweekly. Her serum CA-125 level decreased dramatically after the first cycle. A computerized tomography scan showed marked regression of the recurrent masses after 3 cycles, and the patient reached complete remission after 9 cycles. She showed good recovery from cachexia. We observed no marked side effects except for mild polyarthritis of the small joints. Conclusions: The therapeutic effect of checkpoint inhibitors combined with angiogenesis inhibitors is very promising in our patient with OCCC. Further clinical trials of tumors including ARID1A mutations are warranted.