China-based Mabwell will be presenting phase 1b/2a results for 9MW1911, its investigational anti-ST2 monoclonal antibody, showing reductions in chronic obstructive pulmonary disease (COPD) exacerbations at higher doses at the European Respiratory Society International Congress 2026 early this month, the company announced September 4, 2026.¹
The clinical results showed that, compared with placebo, the annualized rate of moderate to severe exacerbations was reduced by 24% and 81% in the 600 mg and 900 mg dose groups, respectively, while the annualized rate of severe exacerbations was reduced by 47% and 100% in those same groups.¹
Key facts
Drug: 9MW1911 (Mabwell)
Class: Anti-ST2 monoclonal antibody (IL-33 receptor blocker)
Indication studied: Chronic obstructive pulmonary disease (COPD)
Trial: 9MW1911 C03; phase 1b/2a, 80 patients
Key data: 24%-81% reduction in moderate-to-severe exacerbations (600/900 mg vs placebo)
Key data: 47%-100% reduction in severe exacerbations (600/900 mg vs placebo)
Safety: Favorable safety and tolerability profile reported
Milestone: First homegrown China-developed anti-ST2 antibody
Regulatory status: FDA IND cleared for phase 2a; phase 2b enrollment complete
Next milestone: Phase 3 trial expected to begin around end of 2026
What did the phase 1b/2a trial evaluate?
The randomized, double-blind, placebo-controlled, dose-escalation trial (9MW1911 C03) enrolled 80 former smokers with moderate to severe COPD, most with blood eosinophil counts of 300 cells/μL or lower, and demographic characteristics generally balanced across dose groups. Participants received intravenous 9MW1911 at doses of 100 mg, 300 mg, 600 mg, or 900 mg, or placebo, every 4 weeks.
Pharmacokinetic data showed trough concentrations reached steady state at approximately week 12, with exposure increasing approximately dose-proportionally across the 100-900 mg range.¹ 9MW1911 showed an overall favorable safety and tolerability profile, and the study's primary objective was to evaluate safety, tolerability, and pharmacokinetics, with efficacy and immunogenicity assessed as secondary measures, according to the company.¹
Why does targeting the interleukin-33/ST2 pathway matter in COPD?
COPD affects an estimated 400 million people worldwide and remains among the leading causes of death globally, with more than half of patients experiencing exacerbations despite maintenance inhaled therapies.² 9MW1911 targets ST2, the receptor for interleukin-33 (IL-33), a cytokine implicated in airway inflammation and mucus dysfunction that has emerged as a target of interest across COPD independent of eosinophil levels.¹
In related news, a separate antibody targeting IL-33 itself, tozorakimab (AstraZeneca), showed positive phase 3 results in COPD across broad patient populations, it was reported in March 2026.³ The trial results for both these antibody candidates suggest that targeting the IL-33 pathway can deliver meaningful clinical benefit in COPD, which is known to be a difficult-to-treat disease that carries inherent heterogeneity and significant unmet need.³
What's next for 9MW1911?
According to Mabwell, 9MW1911 is the first homegrown monoclonal antibody targeting ST2 developed in China. It was generated using the company's proprietary high-efficiency B lymphocyte screening platform.¹ Enrollment is complete for a larger phase 2b study, and Mabwell expects to initiate a phase 3 trial around the end of 2026. The company said FDA has also cleared an investigational new drug application for a phase 2a trial of 9MW1911 in patients with moderate to severe COPD in the United States.¹
What are the limitations?
These are preliminary, poster-presented topline results from a small, 80-patient trial not powered for definitive efficacy conclusions. The 600 mg and 900 mg efficacy comparisons involve small subgroup sizes, and full statistical significance was not reported for the exacerbation-reduction findings.
References
- Mabwell (Shanghai) Bioscience. ERS 2026 | Mabwell presents Phase Ib/IIa clinical results of anti-ST2 monoclonal antibody 9MW1911 in COPD patients. Press release. Published September 4, 2026. Accessed September 4, 2026. https://www.mabwell.com/en/news_info/id-244.html
- de Oca MM, Perez-Padilla R, Celli B, et al. The global burden of COPD: epidemiology and effect of prevention strategies. Lancet Respir Med. 2025;13(8):709-724. doi:10.1016/S2213-2600(24)00339-4
- AstraZeneca. Tozorakimab met primary endpoint in both OBERON and TITANIA Phase III trials in patients with COPD. Published March 27, 2026. Accessed September 4, 2026. https://www.astrazeneca.com/media-centre/press-releases/2026/tozorakimab-met-primary-endpoint-in-oberon-titania-phase-iii-trials-in-patients-with-copd.html
