Mabwell’s COPD antibody cuts exacerbations up to 81% as Phase III approaches

Mabwell (SSE: 688062; HKEX: 02493) has reported an eye-catching early clinical signal for its experimental chronic obstructive pulmonary disease antibody 9MW1911, with the highest tested dose associated with an 81% reduction in the annualised rate of moderate-to-severe exacerbations compared with placebo.

The same 900mg dose was associated with a 100% reduction in annualised severe COPD exacerbations, while the 600mg arm showed reductions of 24% for moderate-to-severe exacerbations and 47% for severe exacerbations. Mabwell disclosed the results from its Phase Ib/IIa 9MW1911-C03 study ahead of presentation at the European Respiratory Society International Congress 2026.

Those percentages are potentially important but require unusually careful interpretation.

Only 80 participants were enrolled across placebo and four active-dose groups of 100mg, 300mg, 600mg and 900mg, and the study’s primary objective was safety, tolerability and pharmacokinetics rather than establishing definitive treatment efficacy. Exacerbation outcomes were preliminary efficacy assessments generated from a relatively small dose-escalation trial.

Mabwell is nevertheless moving quickly. The company says enrolment in a larger Phase IIb COPD study has already been completed and expects to initiate Phase III around the end of 2026. The United States Food and Drug Administration has also cleared an investigational new drug application for a separate Phase IIa COPD study in the United States.

Why is an 81% reduction in COPD exacerbations interesting but not yet decisive?

COPD exacerbations are clinically and economically important because worsening episodes can lead to emergency treatment, hospitalisation, accelerated loss of lung function and substantial healthcare costs.

A therapy capable of materially reducing those events could therefore address an important unmet need.

The problem is that large percentage reductions can emerge from small studies when the absolute number of events is limited. With only 80 patients spread across five groups, each treatment arm is necessarily small, making individual events capable of moving annualised rates substantially.

Mabwell itself describes the efficacy findings as preliminary signals rather than definitive evidence.

That distinction should remain at the centre of the investment interpretation.

The 81% reduction at 900mg is considerably stronger than the 24% reduction seen at 600mg for moderate-to-severe exacerbations. That could represent a genuine dose-response relationship, but the study is too small to conclude that the high-dose effect will reproduce at scale.

The completed Phase IIb study therefore becomes critical because it can test the signal in a substantially larger population before Mabwell commits fully to pivotal development.

What is Mabwell targeting with the 9MW1911 anti-ST2 antibody?

9MW1911 is a monoclonal antibody targeting ST2, a receptor involved in inflammatory signalling.

COPD is biologically heterogeneous, which means patients can have different inflammatory drivers even when they share the same broad clinical diagnosis. Drug developers have therefore been searching for more precise inflammatory pathways that could produce meaningful reductions in exacerbations for selected populations.

Mabwell’s early study is notable because most participants had blood eosinophil counts of 300 cells per microlitre or lower.

That characteristic could become important if later studies confirm efficacy because several biologic approaches to airway disease have historically focused on patients with more pronounced eosinophilic inflammation.

The company has not yet established that 9MW1911 works across a broad COPD population. What it has shown is that sufficient early safety and pharmacokinetic evidence exists to justify further testing, alongside a preliminary exacerbation signal at the higher doses.

Pharmacokinetic analysis found exposure increased approximately proportionally across the 100mg to 900mg range, while trough concentrations reached steady state at around week 12. Mabwell characterised overall safety and tolerability as favourable in the study.

Later-stage trials will need to test those observations across many more patients and longer follow-up.

Why is Mabwell already talking about Phase III before the larger efficacy dataset is public?

The development sequence shows Mabwell is attempting to compress the time between early clinical validation and pivotal testing.

Phase Ib/IIa has finished, Phase IIb enrolment is complete and Phase III is expected to begin around the end of 2026. Meanwhile, the FDA has cleared a US Phase IIa study.

That creates several overlapping clinical workstreams.

If the Phase IIb data reinforce the dose-response and exacerbation findings, entering Phase III relatively quickly could give Mabwell an opportunity to establish 9MW1911 as a globally relevant respiratory programme rather than a China-only asset.

The opposite scenario is equally important.

If the larger trial shows a much smaller effect than the early 900mg signal, Mabwell may need to reconsider dose selection, target population, statistical assumptions or the timing of Phase III.

The fact that a Phase III start is planned does not mean pivotal success has been de-risked. It means the company is preparing operationally to move quickly if the supporting evidence remains favourable.

How did Mabwell shares respond to the COPD data?

Mabwell’s Shanghai-listed shares closed at CNY27.42 on September 4, down 2.63% for the session after gaining 2.29% on September 3. The stock had closed at CNY28.33 on August 31, meaning it declined about 3.2% across the four September trading sessions through September 4.

That trading pattern provides no evidence that investors immediately treated the COPD release as a decisive value-creating event.

The restrained reaction is understandable because 9MW1911 remains an investigational programme and the most impressive percentages come from a small early-stage study.

Investors are likely to place substantially greater weight on Phase IIb results and the eventual Phase III design.

Mabwell is also a broader biopharmaceutical company with multiple clinical and commercial programmes, meaning daily share movements cannot safely be attributed to a single study update without stronger evidence.

The clinical signal nonetheless gives investors a new data point to monitor. A reproducible reduction in exacerbations across a larger controlled trial would materially change the credibility of the programme.

What would make 9MW1911 commercially meaningful in the COPD market?

Three things need to happen.

First, Mabwell must reproduce the efficacy signal in a larger study. An 81% reduction from a small Phase Ib/IIa cohort is interesting; a statistically robust and clinically meaningful reduction in a larger randomised trial would be far more valuable.

Second, dose selection needs to become clearer. The apparent difference between the 600mg and 900mg groups suggests dose may matter substantially, but larger datasets are needed to determine whether that pattern is real and whether a higher dose remains practical from safety, manufacturing and commercial perspectives.

Third, Mabwell will need to identify the patient population most likely to benefit.

COPD encompasses a broad range of inflammatory phenotypes, smoking histories, exacerbation patterns and coexisting treatments. A biologic that works exceptionally well in a definable subgroup can still become commercially attractive even if it is not appropriate for every COPD patient.

The upcoming Phase IIb data should therefore tell investors far more than the current headline percentages.

Mabwell has produced a signal strong enough to justify attention and is preparing for Phase III around year-end. It has not yet produced evidence strong enough to call 9MW1911 a proven COPD therapy.

That gap between an 81% early signal and reproducible late-stage efficacy is now the entire story.