Analysis of Treatment-Free Survival of Patients with Advanced Melanoma Receiving Nivolumab As Monotherapy or in Combination with Relatlimab in RELATIVITY-047

BACKGROUND:Treatment-free survival (TFS; time spent free of systemic anticancer therapy) is increasingly used to support traditional endpoints. TFS was previously evaluated in patients with advanced melanoma treated with nivolumab plus ipilimumab. This analysis compared TFS for nivolumab plus relatlimab and nivolumab monotherapy in patients with advanced melanoma. METHODS:Data were from 714 patients in the phase 2/3 RELATIVITY-047 trial (ClinicalTrials.gov identifier: NCT03470922). TFS was defined as the difference in restricted mean event times between the Kaplan-Meier curves for time to protocol therapy cessation and time to subsequent systemic anticancer therapy initiation or death. TFS was further partitioned into time with and time without grade ≥3 treatment-related adverse events (TRAEs). Subgroup analysis based on tumor BRAF mutational status and tumor programmed death ligand 1 (PD-L1) expression level was conducted. Between-treatment group differences were calculated with bootstrapped 95% CIs. RESULTS:At 48 months from randomization, Kaplan-Meier estimates of overall survival were 52% and 43% for patients in the nivolumab plus relatlimab and nivolumab groups, respectively; 38% and 33% of patients in these respective groups were free of subsequent systemic therapy. The 48-month mean TFS was 2.9 months (95% CI 1.0 to 4.9) longer with nivolumab plus relatlimab than with nivolumab (9.7 vs 6.8 months, respectively). Mean TFS represented 20% and 14% of the 48-month period after initiating nivolumab plus relatlimab and nivolumab, respectively. Considering only time without grade ≥3 TRAEs, the 48-month mean TFS was 2.6 months (95% CI 0.8 to 4.5) longer with nivolumab plus relatlimab than with nivolumab (9.1 vs 6.5 months, respectively). The 48-month mean total TFS was consistently longer with nivolumab plus relatlimab than with nivolumab in the BRAF mutant (9.4 vs 6.5 months), BRAF wild-type (9.9 vs 6.9 months), PD-L1 ≥1% (12.3 vs 7.7 months), and PD-L1<1% (7.9 vs 6.2 months) subgroups. CONCLUSIONS:This analysis demonstrated TFS benefit during the 48 months since initiating nivolumab plus relatlimab compared with nivolumab alone in patients with advanced melanoma. A direct comparison between nivolumab plus relatlimab and nivolumab plus ipilimumab is needed to determine the differences between the regimens in TFS and those in traditional endpoints.