Nivolumab and hypofractionated radiotherapy in patients with advanced melanoma: A phase 2 trial

Background: Radiotherapy is thought to enhance anti-tumor immunity, particularly when delivered in a hypofractionated and multisite manner. Therefore, we investigated the effects of combining radiotherapy with nivolumab in patients with advanced melanoma.Methods: This was a multicenter, non-randomized, phase 2 trial that enrolled patients with treatment-naïve metastatic melanoma. They received nivolumab (240 mg / 2 weeks) plus radiotherapy (day 15, 6 Gy × 3). When feasible, one target from each organ was irradiated (no irradiation of all targets). The primary endpoint was 1-year overall survival (OS).Results: This trial included 64 patients between March 2017 and July 2019. The median follow-up was 23.5 (2.3-43.8) months. The median age was 68 (35-95) years, patients were mostly male (67 %) with an Eastern Cooperative Oncology Group Performance Status (ECOG-PS) score of 0 (72 %), stage IV-M1c disease (47 %), and were BRAF-wild-type (67 %). The 2-year OS and 1-year PFS rates were 65.2 % and 56 %, respectively (P = 0.22 and P = 0.03, vs. 58 % and 43 %, respectively, in the Checkmate 066 study). Thirty-seven (58 %) and twenty-seven (42 %) patients were irradiated at one and multiple targets, respectively. The ECOG-PS (1 vs. 0; HR = 3.5; P = 0.005) was an independent prognostic factor for OS. Irradiating more than one site and irradiating a smaller cumulative tumor volume tended to correlate with better outcome. Grade 3-4 treatment-related adverse events occurred in 21.9 % of the patients (no grade 5).Conclusions: Combined immunotherapy and hypofractionated radiotherapy did not improve survival compared to historical cohorts. The radiotherapy schedule needs to be optimized in order to improve these results.