Connect Biopharma's rademikibart cuts asthma treatment failure by 66%

Connect Biopharma has reported positive preliminary topline data from its Phase 2 Seabreeze STAT Asthma study, showing that rademikibart, its anti-IL-4Rα monoclonal antibody, reduced treatment failure rates and improved lung function in adults and adolescents hospitalised with acute asthma exacerbations and type 2 inflammation.

The randomised, double-blind, placebo-controlled trial enrolled 160 participants globally, assigned 1:1 to receive either a single 600mg subcutaneous dose of rademikibart added to standard of care, or placebo. Participants were required to have an eosinophil count of at least 300 cells per microlitre, defining the high type 2 inflammatory phenotype the drug is designed to target.

Trial results

The study's key secondary endpoint, an absolute improvement in post-bronchodilator forced expiratory volume in one second (FEV1) at Day 7, was met with statistical significance. Rademikibart-treated patients gained 250 mL from baseline versus 120 mL in the placebo arm, a 130 mL difference that reached significance (p=0.023). The primary endpoint, treatment failure within 28 days, was reduced by approximately 66% compared with placebo, including a 50% reduction in emergency department revisits and unscheduled medical visits, though this endpoint did not reach statistical significance (p=0.153). The company attributed the statistical miss to a lower-than-projected overall treatment failure rate in the study population, which compressed the difference between arms.

The safety profile was encouraging. No new safety signals emerged, adverse events were infrequent in both arms, no participant discontinued due to an adverse event, and only one serious adverse event was recorded in the rademikibart arm compared with three in the placebo arm.

Barry Quart, chief executive of Connect Biopharma, said the results "provide a clear roadmap for design of a Phase 3 programme," adding that updated market research recorded approximately 1.6 million emergency department visits in 2025 attributable to high-type-2 acute asthma exacerbations in the United States alone.

Market context and competitive landscape

Rademikibart targets IL-4Rα, the same receptor subunit blocked by dupilumab (Sanofi/Regeneron's Dupixent), which is already approved for maintenance treatment in moderate-to-severe asthma. The acute exacerbation setting is distinct and less developed: no biologic is yet approved specifically as add-on therapy during an acute asthma episode, representing a potential commercial gap that Connect is explicitly pursuing.

The IL-4Rα class has attracted significant investment, and several companies are advancing next-generation IL-4Rα or IL-13-targeted agents, including candidates from mid-size biotechs and larger pharmaceutical groups. Connect will need to demonstrate in Phase 3 that the FEV1 gain and treatment failure reduction translate at scale and reach statistical significance on both endpoints simultaneously to differentiate rademikibart in a competitive field.

Connect holds an exclusive licence with Simcere Pharmaceutical for Greater China, with up to approximately $99 million in remaining development, regulatory, and commercial milestones plus tiered royalties, providing a non-dilutive funding stream alongside its NASDAQ-listed capital base.

Regulatory path

The company expects to report topline data from its parallel Phase 2 Seabreeze STAT COPD study later this month. Connect plans to use both datasets to seek FDA alignment on a Phase 3 registrational programme covering acute exacerbations in both asthma and COPD. The proposed primary endpoint for Phase 3 is the FEV1 measure at Week 1, the endpoint that already achieved significance in the Phase 2 asthma trial, which may reduce execution risk in the pivotal study design.

Analysts and investors will watch closely for the COPD readout and the company's characterisation of the FDA pre-Phase-3 meeting, given that the primary endpoint in the Phase 2 asthma trial technically missed. The direction of travel, however, and the strength of the lung function data, leave the programme on a credible development path.