LAUSR

Abstract Background and Objective: Nivolumab and Ipilimumab are immune checkpoint inhibitors. The combination of Nivolumab and Ipilimumab has been reported to have complementary effects in the treatment of metastatic melanoma. The combination therapy of Nivolumab and Ipilimumab (N+I) has shown synergistic effects in cancer immunotherapy but this is still controversial due to the higher incidence of toxicity. Hence, we conducted a meta-analysis to evaluate the efficacy and safety profile of Nivolumab combined with Ipilimumab and compared the different dosing schedules of the N+I combination. Methods: By searching in PubMed, PMC, Cochrane library and major conference abstracts, eligible sixteen studies including N+I therapy and Nivolumab monotherapy were selected to analyze overall response rate (ORR), progression-free survival (PFS), overall survival (OS), and high-grade (3-4) adverse effects (AEs). Results: Compared with monotherapy of Nivolumab, N+I significantly improved ORR (RR=1.40 [95% CI 1.27, 1.54], P<0.00001) and PFS (Hazard Ratio (HR)=0.83 [95% CI 0.77, 0.90], P<0.00001), but not OS (HR=0.93 [95% CI 0.84, 1.03], P=0.16). In a sub-analysis, the combination of Nivolumab 1mg/kg plus Ipilimumab 3mg/kg (N1I3) and Nivolumab 3mg/kg plus Ipilimumab 1mg/kg (N3I1) achieved better ORR and PFS than Nivolumab 3mg/kg (N3) alone. Remarkably, OS was also prolonged with the N1I3 combination compared with the N3I1 combination or N3. Furthermore, a higher incidence of high-grade AEs also occurred with the combination therapy of N1I3. Conclusions: N+I combination therapy showed greater ORR and PFS compared with Nivolumab monotherapy. N1I3 combination provided the benefit of ORR, PFS and OS but was associated with a higher incidence of toxicity.