SINOMAB BIO-B (03681) has announced that on March 31, 2026, the first patient in its Phase 2 clinical trial for SM17 in treating atopic dermatitis was successfully dosed in China. This Phase 2 study is a multicenter, randomized, double-blind, placebo-controlled trial designed to evaluate the efficacy and safety of a subcutaneous formulation of SM17 in approximately 210 patients with moderate-to-severe atopic dermatitis. Patients will be randomized in a 1:1:1:1:1 ratio into five groups to receive different doses of SM17 or a placebo subcutaneously. The primary endpoint is the percentage change from baseline in the Eczema Area and Severity Index (EASI) at week 16. Secondary endpoints, including other efficacy measures such as the proportion of subjects achieving EASI50, EASI75, EASI90, and IGA0/1, safety endpoints defined by the incidence of treatment-emergent adverse events (TEAEs), as well as pharmacokinetic (PK) profile, pharmacodynamic (PD) profile, and immunogenicity, will be assessed at week 16 and at other time points up to week 24.

SM17 is a novel, first-in-class humanized IgG4-k monoclonal antibody designed to regulate type 2 inflammatory responses by targeting the receptor for interleukin-25 (IL-25), an alarmin molecule that plays a central role in type 2 immunity. By binding to the IL-25 receptor (IL-17RB) on type 2 innate lymphoid cells (ILC2s) and Th2 cells, SM17 inhibits IL-25-mediated signaling and suppresses downstream inflammatory cytokines, including IL-4, IL-5, and IL-13. IL-25 is a key cytokine classified as an alarmin and has been implicated in the pathogenesis of various inflammatory and immune diseases, such as atopic dermatitis, asthma, and inflammatory bowel disease (IBD). Despite advances in targeted therapies, these chronic inflammatory and immune-mediated conditions continue to impose a significant disease burden, including persistent symptoms, progressive tissue damage, and severely impaired quality of life. While current treatments are effective for many patients, they are often limited by safety concerns, poor adherence, and a failure to achieve sustained remission in some individuals. These unmet medical needs highlight the persistent demand for new therapeutic options with improved convenience, favorable safety profiles, and differentiated efficacy.

On April 7, 2025, the company announced positive topline results from its Phase 1b study of SM17 in Chinese patients with moderate-to-severe atopic dermatitis. Key data after the 12-week unblinding showed that in the high-dose group, 91.7% of patients achieved itch relief (NRS-4), 75% achieved skin lesion healing (EASI 75), and 41.7% achieved complete or almost complete clearance of atopic dermatitis signs (IGA 0/1). These results demonstrate SM17's competitive advantage as a potential first-in-class biologic for atopic dermatitis that offers dual efficacy in relieving itch and repairing skin.

On March 27, 2026, the company reported ideal topline results from a Phase 1 bridging study on the route of administration for SM17: healthy subjects receiving the subcutaneous formulation exhibited good tolerability and safety, and the pharmacokinetic profile supported a successful switch in the administration route. The company believes that upstream therapies targeting the Th2 inflammatory cytokine pathway, such as those involving the IL-25 receptor, will have a broad effect on skin inflammation, indicating that SM17 holds significant potential for being a safer, more effective, and differentiated treatment for atopic dermatitis.