The checkpoint inhibitor nivolumab is active in metastatic melanoma patients who have failed ipilimumab. In this phase I/II study, we assessed nivolumab's safety in 92 ipilimumab refractory patients with unresectable stage III or IV melanoma, including those who experienced grade 3-4 drug related toxicity to ipilimumab. We report long-term survival, response duration, and biomarkers in these patients after nivolumab treatment (3 mg/kg) every 2 weeks for 24 weeks, then every 12 weeks for up to 2 years, with or without a multipeptide vaccine. Response rate for ipilimumab-refractory patients was 30% (95%CI: 21% - 41%). Median duration of response was 14.6 months, median progression-free survival was 5.3 months, and median overall survival was 20.6 months, when followed up a median of 16 months. One and two year survivals were 68.4% and 31.2%, respectively. Ipilimumab-naïve and -refractory patients showed no significant difference in survival. The 21 patients with prior grade 3-4 toxicity to ipilimumab that was managed with steroids, tolerated nivolumab well, with 62% (95%CI: 38% - 82%) having complete or partial remissions or stabilized disease at 24 weeks. High numbers of myeloid-derived suppressor cells (MDSCs) were associated with poor survival. Thus, survival and long-term safety were excellent in ipilimumab-refractory patients treated with nivolumab. Prior grade 3-4 immune-related adverse effects from ipilimumab were not indicative of nivolumab toxicities, and patients had a high overall rate of remission or stability at 24 weeks. Prospectively evaluating MDSC numbers before treatment could help assess the expected benefit of nivolumab.
- Received August 11, 2015.
- Revision received December 7, 2015.
- Accepted January 12, 2016.
- Copyright © 2016, American Association for Cancer Research.