BACKGROUND: GR1603 is a monoclonal antibody targeting the type I interferon receptor. The aim of this study was to evaluate the safety, tolerability, pharmacokinetics, immunogenicity and pharmacodynamics of GR1603 in healthy volunteers. METHODS: Healthy adults (≥18 years old) were enrolled in a placebo control, dose-escalation Phase I clinical trial receiving a single injectable dose of GR1603. Follow-up was 12 weeks. Adverse event (AE) profiles, vital signs, and blood samples were collected for assessment of safety, PK, and expression of type I interferon inducible genes. RESULTS: Of the 46 subjects, 44 completed treatment. In the experimental group of 34 subjects (mean age 26.6 years), 30 experienced treatment-emergent adverse events (TEAEs), with a total of 102 occurrences, resulting in an incidence rate of 88.2%. The most commonly reported drug-related AEs were upper respiratory tract infection (17.6%), all of which were ≤ grade 2. GR1603 exhibits non-linear PK in the dose range of 0.1 mg/kg to 9 mg/kg. All samples were negative for anti-drug antibodies before and after dosing. The degrees of IFN gene signature were significantly inhibited in the higher dose groups. CONCLUSION: The safety/tolerability, PK and exploratory metrics observed in this study support further clinical development of GR1603. CLINICAL TRIAL REGISTRATION: www.chictr.org.cn/searchproj.html identifier is ChiCTR2100045628.