Ovarian carcinosarcoma is a rare malignancy associated with a high rate of cancer-related mortality even at early stages. Guidelines for systemic treatment have been difficult to establish because the disease is commonly excluded from prospective clinical trials. Ovarian carcinosarcoma is usually managed as high-grade epithelial ovarian cancer despite major histologic differences. Owing to the rarity and poor prognosis of ovarian carcinosarcoma, salvage treatments and their efficacy have been poorly described.

A patient heavily treated for ovarian carcinosarcoma showed an objective response to an immune checkpoint inhibitor, pembrolizumab. Pembrolizumab in this patient appeared to provide tumor control in multifocal metastatic sites.

Pembrolizumab should be evaluated in prospective trials for the treatment of ovarian carcinosarcoma and further work is needed to identify patients most likely to respond to this type of intervention.