A Trial of SHR-1703 in Healthy Adults

Inclusion Criteria: * Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form. * Able to read, comprehend and write at a sufficient level to complete study materials. * Aged 18 to 55 years (inclusive). * Body weight equal or more than 45.0 kg and BMI within the range between 19 and 24kg/m2 (inclusive). * AST, ALT, alkaline phosphatase and bilirubin equal or less than ULN. * Healthy Chinese as determined by a responsible and experienced physician, based on a medical evaluation including medical history, physical examination, laboratory tests. A subject with a clinical abnormality or laboratory parameters outside the reference range for the population being studied may be included only if the Investigator and the Jiangsu HengRui Medicine Co Medical Monitor agree that the finding is unlikely to introduce additional risk factors and will not interfere with the study procedures. * Subjects must commit to consistent and correct use of an acceptable method of birth control from the start of trial to the next month after the last visit. * A negative pre-study drug/alcohol screen. Exclusion Criteria: * Allergy/intolerance to the SHR-1703 and/or excipients in the formulation, or any other Biologics * Positive Hepatitis B surface antigen or positive Hepatitis C antibody or human immunodeficiency virus - HIV antibody or Syphilis serological test at screening * The subject has participated in a clinical trial and has received an investigational product within the following time period prior to screening in the current study: 3 months, 5 half-lives or fellow-up period of the investigational product (whichever is longer). * Use of any medicines, including prescription or Over-the-Counter drugs (including herbal and dietary supplements, not including regular vitamins and paracetamol which be used occasionally in the recommended dose) within 1 month or 5 half-lives (whichever is longer) prior to the administration. * Subjects who have received immune inhibitors within 6 months prior to screening * Subjects who have had severe trauma or surgery within 6 months prior to screening, or who plan to undergo surgery during the trial. * Blood donation history within 1 month prior to screening ,or severe blood loss(total blood volume≥400 ml)，or blood transfusion within 2 months * Subjects who are inoculated live (attenuated) vaccine within 1 month prior to screening or during the trial. * Subject who is an immediate family member of the participating investigator, sub-investigator, study coordinator, or employee of the participating investigator. * At the discretion of the investigator, a subject will not be eligible for this study if he/she is in the following cases: the subject is not able to complete the study, or present a significant risk to the subject, or present other factors(e.g. infirmity. etc.) that may prevent the enrolment.