China-based Keymed Biosciences Inc. (HKEX: 02162) announced that its Phase II clinical trial of CM512, a recombinant bispecific antibody targeting both thymic stromal lymphopoietin (TSLP) and interleukin-13 (IL-13), met all study endpoints in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). The company said it is rapidly initiating a Phase III study and has confirmed 300 mg every 24 weeks as the going-forward dosing regimen.
CM512 simultaneously blocks TSLP, an epithelial-derived alarmin that sits upstream of the type 2 inflammatory cascade, and IL-13, a downstream effector cytokine that drives polyp growth and mucosal remodeling. Keymed describes it as the first long-acting IgG-like TSLP × IL-13 dual blocker.
The randomized, double-blind, placebo-controlled Phase II study enrolled 120 patients across three active dosing arms — 300 mg every 12 weeks, 300 mg every 24 weeks, and 600 mg every 24 weeks — plus placebo, over a 24-week treatment period followed by a 12-week safety follow-up. The primary endpoint was change from baseline in nasal polyp score at Week 24. Keymed reported that changes from baseline in nasal polyp score at Week 24 were statistically significantly superior to placebo across all CM512 groups, with comparable efficacy across all three dosing regimens. Reductions in nasal polyp size and nasal congestion were observed as early as Week 4, and the company said olfactory function recovery was also facilitated. The incidence of treatment-emergent adverse events was comparable to placebo, no serious adverse events were reported in CM512 groups, and anti-drug antibody rates were described as extremely low. No specific numerical data were disclosed; Keymed said detailed results will be presented at future international journals or conferences.
The selection of 300 mg Q24W — a twice-yearly subcutaneous dosing schedule — as the Phase III regimen reflects pharmacokinetic data from the completed Phase I study, which demonstrated a half-life of up to 70 days. That profile, reported in the Journal of Translational Medicine in April 2026, supports extended dosing intervals and would differentiate CM512 from Sanofi/Regeneron's Dupixent (dupilumab) and GSK's Nucala (mepolizumab), both of which require more frequent injections in CRSwNP. Amgen/AstraZeneca's Tezspire (tezepelumab), approved for CRSwNP in October 2025, also targets TSLP as a monotherapy; CM512's dual TSLP/IL-13 blockade represents a mechanistically distinct approach, though cross-trial comparisons of efficacy are not possible without head-to-head data.