Primary Analysis and 4-Year Follow-Up of the Phase III NIBIT-M2 Trial in Melanoma Patients With Brain Metastases

Purpose: Phase II trials have shown encouraging activity with ipilimumab plus fotemustine and ipilimumab plus nivolumab in melanoma brain metastases. We report the primary analysis and 4-year follow-up of the NIBIT-M2 study, the first phase III trial comparing these regimens with fotemustine in patients with melanoma with brain metastases. Patients and methods: This phase III study recruited patients 18 years of age and older with BRAF wild-type or mutant melanoma, and active, untreated, asymptomatic brain metastases from nine centers, randomized (1:1:1) to fotemustine, ipilimumab plus fotemustine, or ipilimumab plus nivolumab. The primary endpoint was overall survival (OS). Results: From January, 2013 to September, 2018, 27, 26, and 27 patients received fotemustine, ipilimumab plus fotemustine, and ipilimumab plus nivolumab. Median OS was 8.5 months [95% confidence interval (CI), 4.8-12.2] in the fotemustine arm, 8.2 months (95% CI, 2.2-14.3) in the ipilimumab plus fotemustine arm (HR vs. fotemustine, 1.09; 95% CI, 0.59-1.99; P = 0.78), and 29.2 months (95% CI, 0-65.1) in the ipilimumab plus nivolumab arm (HR vs. fotemustine, 0.44; 95% CI, 0.22-0.87; P = 0.017). Four-year survival rate was significantly higher for ipilimumab plus nivolumab than fotemustine [(41.0%; 95% CI, 20.6-61.4) vs. 10.9% (95% CI, 0-24.4; P = 0.015)], and was 10.3% (95% CI, 0-22.6) for ipilimumab plus fotemustine. In the fotemustine, ipilimumab plus fotemustine, and ipilimumab plus nivolumab arms, respectively, 11 (48%), 18 (69%), and eight (30%) patients had treatment-related grade 3 or 4 adverse events, without treatment-related deaths. Conclusions: Compared with fotemustine, ipilimumab plus nivolumab significantly improved overall and long-term survival of patients with melanoma with asymptomatic brain metastases.