Randomised, double-blind, parallel group Phase I study to compare PK profiles and to assess the safety and immunogenicity between HLX02 and Herceptin® (U.S. and EU).

Inclusion Criteria:

1. Voluntarily signed Informed Consent Form
2. Healthy Chinese male (healthy is defined as the fact that no clinically significant abnormalities are identified by medical history, physical examination, vital signs, chest X ray, 12-lead ECG and laboratory tests)
3. Aged ≥ 18 and ≤ 45 years
4. Body mass index (BMI) ≥ 19 and ≤ 28 kg/m2
5. Body weight ≥ 50 and ≤ 80 kg
6. LVEF within normal range as examined through echocardiogram within 14 days prior to randomization (>50%)
7. Immunogenicity (anti-drug [anti-trastuzumab] antibody [ADA]) tested as negative
8. Subject agrees that he and his female spouse/partner use reliable contraceptive methods from the time of administration of study drug until 3 months after the end of study, or subject is infertile

Exclusion Criteria:

1. Any clinically serious disease history or allergic disease, such as hematologic, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, mental and nervous diseases and tumor
2. Use of monoclonal antibodies or any biological agent within 6 months prior to the administration of the study drug
3. History of allergic reactions, including allergic reactions caused by any drug or excipient in clinical study
4. Use of any prescription or non-prescription drug or dietary supplement within 5 half lives of such drug or dietary supplement or 2 weeks prior to the administration of the study drug (whichever is longer). The traditional Chinese medicine-based dietary supplement should be discontinued 28 days prior to administration of the study drug
5. Donation of blood within 3 months prior to the administration of the study drug
6. Participation in other clinical studies within 3 months prior to the administration of the study drug
7. Positive test result(s) for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody, human immunodeficiency virus (HIV) antibody and treponema pallidum
8. History of drug abuse
9. Inability to follow the protocol requirements, instructions and study limitations as judged by investigators, such as noncooperation, inability to return to the site for follow-up visits or inability to complete the whole clinical study
10. Subject confirmed SARS-CoV-2 infection by appropriate test (including but not limited to nucleic acid test) in screening period