A Study Comparing a Pre-filled Safety Syringe and an Autoinjector for SHR-1703 Injection in Healthy Participants

Prior treatment

• Participation in another drug/device clinical trial within 3 months prior to screening (defined as signed ICF and received study drug/device, or still in follow-up or within 5 half-lives of prior investigational drug, whichever is longer).
• Use of any prescription drugs, OTC drugs, or herbal medicines within 1 month prior to dosing (except routine vitamins ≤100% RDA or occasional paracetamol ≤2 g/day for ≤5 days/month), or less than 5 half-lives washout.
• Major trauma or surgery within 6 months prior to screening, or planned surgery during the study.
• Blood donation or significant blood loss (≥400 mL) within 1 month, or blood transfusion within 2 months prior to screening.
• Receipt or planned receipt of live (attenuated) vaccine within 1 month prior to dosing or during the study.
• Suspected or confirmed parasitic infection within 6 months prior to screening.

Other illness

• Suspected or confirmed active tuberculosis (clinical symptoms or imaging evidence within 3 months).
• Any other condition deemed by the investigator to preclude study participation or increase risk to the participant.

Lab values

• AST, ALT, or bilirubin \> ULN at screening/baseline.
• eGFR \< 90 mL/min/1.73m² at screening/baseline.
• Positive for HBsAg, HBcAb with HBV-DNA \> ULN, HIV-Ab, syphilis serology, or HCV-Ab at screening.

Other

• Clinically significant abnormal blood pressure (SBP \>140 or \<90 mmHg; DBP \>90 or \<60 mmHg) at screening/baseline.
• QTcF \> 450 ms on repeated 12-lead ECG at screening/baseline.
• Pregnant or breastfeeding women, or positive pregnancy test (HCG).
• Investigator or site personnel directly involved in the study.

• Aged 18-55 years at ICF signing.
• Screening BMI 19-26 kg/m², weight 50-80 kg.
• Normal or NCS findings at screening/baseline: physical exam, lab tests (CBC, blood chemistry, UA, coagulation), ECG, abdominal ultrasound, chest X-ray.
• Investigator-assessed absence of diseases that could significantly impact the study or pose additional health risks; stable health expected, no medical intervention needed. Clinically significant lab abnormalities may be retested within 1 week if justified; retest results determine eligibility.
• Females of childbearing potential and males with female partners of childbearing potential must avoid sperm/egg donation, have no pregnancy plan, and use appropriate contraception from ICF signing through 14 months post-last dose (see Section 13.1.2).
• No heavy smoking (\<5 cigarettes/day) or alcohol abuse (≤15 g/day \[e.g., 450 mL beer, 150 mL wine, or 50 mL low-alcohol liquor\], ≤2×/week) within 6 months pre-screening; no drug abuse history. Negative drug screen and alcohol breath test at baseline.