SinoMab BioScience Limited disclosed encouraging topline results from a Phase 1 bridging study assessing the subcutaneous (SC) formulation of its first-in-class monoclonal antibody SM17 in mainland China.
The randomized, double-blind, placebo-controlled trial enrolled 30 healthy participants who received single ascending SC doses of SM17, intravenous (IV) SM17, or placebo. Primary objectives were safety, tolerability and absolute bioavailability; pharmacokinetics (PK) and immunogenicity were secondary endpoints.
Safety outcomes were favorable across all cohorts. No serious adverse events occurred, and no treatment-emergent adverse events (TEAEs) of Grade ≥3 were reported. TEAEs in the SC groups were limited to Grade 1-2 events, with only one mild injection-site rash resolving within an hour. No participant discontinued the study, and vital signs, laboratory parameters and ECG readings showed no clinically relevant changes.
PK analysis indicated a predictable profile for the SC formulation. SM17 displayed a prolonged absorption phase via the SC route, while terminal half-life was comparable to IV administration. Maximum serum concentration (Cmax) and area under the curve (AUC) rose approximately dose-proportionally, and calculated absolute bioavailability was judged robust relative to a potential effective IV dose.
Immunogenicity remained low. Although a small percentage of anti-drug antibodies were detected, they were non-neutralizing and had no observable impact on safety or PK parameters.
The latest data complement previous findings: (1) a U.S. first-in-human Phase 1 trial completed in early 2024 demonstrated a clean safety profile; (2) a China-based Phase 1b proof-of-concept study in moderate-to-severe atopic dermatitis (AD) patients yielded positive efficacy signals announced in April 2025; and (3) an investigational new drug application for inflammatory bowel disease (IBD) received Chinese regulatory clearance in February 2026.
Based on the bridging results, SinoMab plans to initiate a Phase 2 clinical study of SC SM17 in AD patients in China as early as mid-2026. Detailed trial data are expected to be presented at upcoming academic forums.