Early experiences with PD-1 inhibitor treatment of platinum resistant epithelial ovarian cancer

Objective: In this study, we evaluated the toxicity and clinical efficacy of nivolumab, a programmed cell death protein 1 (PD-1) inhibitor, on patients with platinum resistant ovarian cancer. Methods: Every second week, 18 patients with platinum resistance ovarian cancer received nivolumab until disease progression occurred. We assessed toxicity, disease control rate, progression free survival (PFS) and overall survival (OS). Radiological response evaluation according to irRECIST was performed every 12th week, while clinical evaluation was done every second week. Results: The disease control rate was 44% (95% confidence interval [CI]=19-87) as 8 showed stable disease, 6 showed progressive disease and 4 died before the first radiological response evaluation. The median OS was 30 weeks (95% CI=14-42; range, 3-95), and PFS was 15 weeks (95% CI=13-17). The median follow-up time was 30 weeks (range, 3-123). The rate of grade 2-5 adverse events was 28% (5 out of 18). Two patients (11%) developed grade 2 and 3 adverse events, respectively, while no grade 4 events were observed. One patient died from intestinal perforation, believed to be caused by concomitant bevacizumab rather than nivolumab. Conclusion: This study shows few adverse events, and promising clinical efficacy when using nivolumab for ovarian cancer.