Persistent response of an ovarian cancer patient after a short-term single-agent immunotherapy: a case report.

Epithelial ovarian cancer is extremely difficult to treat due to its high recurrence rate and acquired tolerance to chemotherapy. Immune checkpoint inhibitors (ICIs) are expected to be promising solutions for treatment failure. However, the low response rate to a single ICI agent was demonstrated in approximately all published clinical trials. Surprisingly patients with complete response were also noticed as an anecdote. Proper indicators of treatment response were urgently required. Programmed death- ligand 1 expression levels in the tumor tissues provide relatively limited discrimination. Tumor mutation burden (TMB) serves as a more reliable parameter. Here we presented an ovarian cancer case with multiple gene mutations and high TMB, who benefited from a short-term treatment of pembrolizumab and experienced a long-lasting complete response of 2 years till now. The patient was irradiated in the pelvic before pembrolizumab. Our study demonstrated that ICIs might provide survival benefits for ovarian cancer with high TMB and that pelvic radiation might have synergistical effects with immunotherapy.