Abstract
Promising antitumor activities of nivolumab, a fully humanized IgG4 inhibitor antibody against the programmed death-1 protein, were suggested in previous phase 1 studies. The present phase 2, single-arm study (JAPIC-CTI #111681) evaluated the antitumor activities of nivolumab and explored its predictive correlates in advanced melanoma patients at 11 sites in Japan. Intravenous nivolumab 2 mg/kg was given repeatedly at 3-week intervals to 35 of 37 patients enrolled from December 2011 to May 2012 until they experienced unacceptable toxicity, disease progression, or complete response. Primary endpoint was objective response rate. Serum levels of immune modulators were assessed at multiple time points. As of 21 October 2014, median response duration, median progression-free survival, and median overall survival were 463 days, 169 days, and 18.0 months, respectively. The overall response rate and 1- and 2-year survival rates were 28.6%, 54.3%, and 42.9%, respectively. Thirteen patients remained alive at the end of the observation period and no deaths were drug related. Grade 3-4 drug-related adverse events were observed in 31.4% of patients. Pretreatment serum interferon-γ, and interleukin-6 and -10 levels were significantly higher in the patients with objective tumor responses than in those with tumor progression. In conclusion, giving repeated i.v. nivolumab had potent and durable antitumor effects and a manageable safety profile in advanced melanoma patients, strongly suggesting the usefulness of nivolumab for advanced melanoma and the usefulness of pretreatment serum cytokine profiles as correlates for predicting treatment efficacy.