BACKGROUNDNivolumab (Opdivo®) is the first anti-PD-1 antibody approved in the world. LY01015 is a potential biosimilar of nivolumab.OBJECTIVESThis phase I study aimed to establish the pharmacokinetic equivalence between LY01015 and the original investigational nivolumab (Opdivo®) in healthy Chinese male subjects. Additionally, safety and immunogenicity were assessed.PATIENTS AND METHODSA randomized, double-blind, parallel-controlled, phase I trial was conducted with 176 healthy male adults receiving a single intravenous infusion of LY01015 or nivolumab at 0.3 mg/kg. Pharmacokinetics, safety, and immunogenicity were evaluated over a 99-day period. The primary pharmacokinetics endpoint was AUC0-∞, and the secondary pharmacokinetic endpoints included AUC0-t and Cmax. Pharmacokinetic bioequivalence was confirmed using standard equivalence margins of 80.00-125.00%.RESULTSThis study is the first to report on the pharmacokinetics, safety, and immunogenicity of Opdivo® in healthy individuals. The pharmacokinetics profiles of LY01015 and Opdivo® were found to be comparable. The geometric mean ratios (90% confidence intervals) for the AUC0-∞, AUC0-t, and Cmax of LY01015 to Opdivo® were 94.49% (90.29-98.88%), 94.92% (88.73-101.54%), and 96.55% (93.32-99.90%), respectively, falling within the conventional bioequivalence criteria of 80.00-125.00%. The safety and immunogenicity were also comparable between the two groups.CONCLUSIONSLY01015 demonstrated highly similar pharmacokinetics to nivolumab in healthy Chinese male subjects. Both drugs exhibited comparable safety and immunogenicity profiles.TRIAL REGISTRATIONThis trial is registered at the Chinese Clinical Trial Registry website ( https://www.chictr.org.cn/ #ChiCTR2200064771).