SinoMab BioScience Limited: Major Progress in SM17 Phase 1 Bridging Study for Subcutaneous Administration in China

Key Highlights

• Positive topline results from Phase 1 bridging study for SM17’s administration route conversion (IV to SC) in China.
• Favorable safety and tolerability: Minimum injection reactions, no ≥ Grade 3 drug-related adverse events or serious adverse events.
• Predictable pharmacokinetic (PK) profiles: SC formulation shows dose-proportional exposure and robust bioavailability.
• Low immunogenicity: Non-neutralizing anti-drug antibodies detected, with no impact on safety or PK.
• Phase 2 clinical trial for atopic dermatitis (AD) in China expected to start as early as mid-2026.
• SM17 receives IND approval for IBD in China.

Detailed Study Findings

SinoMab BioScience Limited has announced the successful completion and favorable results of its Phase 1 bridging study for SM17, a novel monoclonal antibody, transitioning from intravenous (IV) to subcutaneous (SC) administration in China. The study enrolled 30 healthy participants, who were randomized to receive ascending doses of SM17 via SC injection, IV injection, or placebo. All follow-up visits were completed in February 2026.

Safety and Tolerability

• Incidence of treatment-emergent adverse events (TEAEs) was comparable across groups.
• No serious adverse events (SAEs) reported in any cohort.
• All TEAEs in SC groups were Grade 1 or 2; no study drug-related TEAEs of Grade ≥3.
• No TEAEs led to study discontinuation.
• Only one injection site reaction (skin rash, Grade 1) resolved spontaneously within one hour.
• No clinically relevant findings in vital signs, laboratory parameters, or ECGs.

Pharmacokinetics and Bioavailability

• SC administration resulted in a prolonged absorption phase.
• Terminal half-life similar between IV and SC routes.
• Maximum serum concentration (Cmax) and area under the curve (AUC) increased dose-proportionally across SC dose range.
• Calculated absolute bioavailability of SC formulation robust and competitive relative to IV dose.

Immunogenicity

• Low percentage of anti-drug antibodies (ADAs) detected; all were non-neutralizing.
• No impact on safety or PK parameters observed.

Implications for Investors

Potential Price Sensitivity: The successful transition to a subcutaneous formulation significantly enhances SM17’s commercial prospects. SC administration offers increased convenience for patients compared to IV, potentially expanding the addressable market and improving patient adherence. The absence of serious safety concerns, robust PK profile, and low immunogenicity further support the drug’s clinical development and commercial viability.

Upcoming Milestones: The Company expects to initiate a Phase 2 clinical study in China for atopic dermatitis (AD) as early as mid-2026. Additionally, SM17 has received IND approval for inflammatory bowel disease (IBD), opening doors for broader application across multiple inflammatory and immunology indications, including asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and idiopathic pulmonary fibrosis (IPF).

About SM17

SM17 is a first-in-class humanized IgG4-k monoclonal antibody targeting the IL-25 receptor (IL17RB), central to Type 2 immunity. By inhibiting IL-25-mediated signaling, SM17 suppresses downstream cytokines (IL-4, IL-5, IL-13) implicated in the pathogenesis of conditions like asthma, AD, and IBD. The dual mechanism of action enables modulation of both Th2 and Th17 pathways, positioning SM17 as a differentiated candidate in the inflammatory and immunology (I&I) sector.

Conclusion

The successful completion and positive outcomes from the Phase 1 bridging study mark a significant milestone for SinoMab BioScience’s SM17 program. The transition to subcutaneous delivery, combined with a favorable safety profile and expansion into multiple indications, could materially impact the Company’s valuation and future growth prospects. Investors should monitor further clinical updates and regulatory milestones, as these developments may drive share price appreciation.

Corporate Information

The announcement was made by Dr. Shui On Leung, Executive Director, Chairman, and CEO of SinoMab BioScience Limited in Hong Kong on 25 March 2026. The Board comprises notable industry figures including Dr. Haigang Chen, Mr. Xun Dong, Ms. Xiaosu Wang, Dr. Jianmin Zhang, Mr. George William Hunter Cautherley, Mr. Ping Cho Terence Hon, Dr. Chi Ming Lee, Ms. Chi Sau Giselle Lee, and Mr. Nan Shen.

Disclaimer

This article is for informational purposes only and does not constitute investment advice. Investors are advised to exercise their own judgment and consult with professional advisors before making any investment decisions. SinoMab BioScience Limited’s future performance is subject to market risks, regulatory approvals, and clinical trial outcomes.

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