OBJECTIVESThe study aimed to explore the bioequivalence of a proposed biosimilar HL02 vs. its reference products (US-trastuzumab) among healthy Chinese men.METHODSIn this study, nine healthy male subjects received single ascending doses of trastuzumab biosimilar (HL02, 2-8 mg/kg), and then a randomized, double-blind, two-arm, parallel study was conducted to investigate the PK similarity of HL02 (6 mg/kg) with that of US-trastuzumab as a reference drug.RESULTSPK properties exhibited by HL02 (N = 55) were similar to those of US-trastuzumab (N = 52). The comparison of biosimilarity with US-trastuzumab showed that the 90% confidence intervals (CIs) of the ratios for Cmax, AUC0-t, and AUC0-∞ were within 80-125%. Nineteen subjects were positive for ADA and negative for NAb in both HL02 and US-trastuzumab groups. In total, 81.67% of subjects in HL02 and 78.95% in US-trastuzumab groups showed treatment-related mild or moderate adverse events, mild elevation of transaminase level being the most common adverse events (AE) recorded.CONCLUSIONSThe PK characteristics and immunogenicity exhibited by HL02 were similar to that of the reference product, US-trastuzumab. The safety profiles were similar in both the treatment groups with mild-moderate adverse effects.