First-Line Nivolumab Plus Relatlimab Versus Nivolumab Plus Ipilimumab in Advanced Melanoma: An Indirect Treatment Comparison Using RELATIVITY-047 and CheckMate 067 Trial Data

PURPOSE Nivolumab plus relatlimab and nivolumab plus ipilimumab have been approved for advanced melanoma on the basis of the phase II/III RELATIVITY-047 and phase III CheckMate 067 trials, respectively. As no head-to-head trial comparing these regimens exists, an indirect treatment comparison was conducted using patient-level data from each trial. METHODS Inverse probability of treatment weighting (IPTW) adjusted for baseline characteristic differences. Minimum follow-ups (RELATIVITY-047, 33 months; CheckMate 067, 36 months) were selected to best align assessments. Outcomes included progression-free survival (PFS), confirmed objective response rate (cORR), and melanoma-specific survival (MSS) per investigator; overall survival (OS); and treatment-related adverse events (TRAEs). A Cox regression model compared PFS, OS, and MSS. A logistic regression model compared cORRs. Subgroup analyses were exploratory. RESULTS After IPTW, key baseline characteristics were balanced for nivolumab plus relatlimab (n = 339) and nivolumab plus ipilimumab (n = 297). Nivolumab plus relatlimab demonstrated similar PFS (hazard ratio HR, 1.08 95% CI, 0.88 to 1.33), cORR (odds ratio, 0.91 95% CI, 0.73 to 1.14), OS (HR, 0.94 95% CI, 0.75 to 1.19), and MSS (HR, 0.86 95% CI, 0.67 to 1.12) to nivolumab plus ipilimumab. Subgroup comparisons showed larger numerical differences favoring nivolumab plus ipilimumab with acral melanoma, BRAF -mutant melanoma, and lactate dehydrogenase >2 × upper limit of normal, but were limited by small samples. Nivolumab plus relatlimab was associated with fewer grade 3-4 TRAEs (23% v 61%) and any-grade TRAEs leading to discontinuation (17% v 41%). CONCLUSION Nivolumab plus relatlimab demonstrated similar efficacy to nivolumab plus ipilimumab in the overall population, including most—but not all—subgroups, and improved safety in patients with untreated advanced melanoma. Results should be interpreted with caution.