Rademikibart Improves FEV1 in Phase 2 Asthma Exacerbation Trial

A single 600 mg dose of rademikibart (CBP-201) produced a statistically significant 130 mL improvement in FEV1 at day 7 versus placebo in the phase 2 Seabreeze STAT Asthma trial, though its primary 28-day treatment-failure endpoint missed significance, Connect Biopharma announced September 15, 2026.^¹

Rademikibart is a fully human monoclonal antibody targeting the interleukin-4 receptor alpha (IL-4Rα) subunit, blocking IL-4 and IL-13 signaling to suppress the Th2 inflammatory pathway.^¹ No IL-4Rα-targeted biologic is currently approved specifically as an add-on rescue therapy for acute asthma exacerbations, a gap Connect Biopharma is positioning rademikibart to address alongside standard-of-care management.^¹ The company plans to engage the FDA on a phase 3 registrational program for rademikibart as an add-on treatment for acute exacerbations of both asthma and chronic obstructive pulmonary disease (COPD).^¹

“66% reduction in treatment failure is an exceptional outcome and is particularly impressive and shows a meaningful improvement over standard-of-care therapy alone,” said Michael Wechsler, MD, director, Cohen Family Asthma Institute, and professor of medicine, National Jewish Health.^¹

What were the primary results of Rademikibart in phase 2 Seabreeze STAT Asthma?

Seabreeze STAT Asthma (CBP-201-206) is a global, randomized, double-blind, placebo-controlled phase 2 trial evaluating rademikibart as an add-on to standard-of-care therapy for acute asthma exacerbations.^² The trial enrolled 160 adult and adolescent participants with an eosinophil count of 300 cells/μL or higher presenting with an acute exacerbation, randomizing 79 to a single 600 mg subcutaneous dose of rademikibart and 81 to placebo.^¹ Connect Biopharma did not disclose individual trial sites or countries in its announcement.^¹

Connect Biopharma did not specify exact age cutoffs for the adult and adolescent population enrolled in the trial.^¹

The primary endpoint was treatment failure at 28 days.^¹ Rademikibart produced a 66% relative reduction in treatment failure compared with placebo, though the result did not reach statistical significance (P=.153), a gap Connect Biopharma attributed to an overall lower-than-projected treatment-failure rate across both arms.^¹ The key secondary endpoint, change in FEV1 from baseline at day 7, favored rademikibart by 130 mL (250 mL vs 120 mL with placebo; P = .023).^¹

What were other end points in Seabreeze STAT Asthma?

Rademikibart was associated with a 50% reduction in emergency department visits or unscheduled medical visits for worsening asthma symptoms compared with placebo, according to Connect Biopharma.^¹ The company did not disclose the exact visit counts or confidence intervals for this endpoint in its topline announcement.^¹

Safety was well tolerated across both arms, with no new safety signals identified, according to Connect Biopharma.^¹ No individual adverse event (AE) affected more than 2 participants in either arm, and no participants discontinued treatment due to an AE.^¹ A total of 1 serious AE occurred in the rademikibart arm compared with 3 in the placebo arm.^¹

Connect Biopharma has not disclosed the nature of the serious AEs reported in either treatment arm.^¹

“Today's data highlight the statistically significant rapid improvements in FEV1 within one week post treatment as well as a 66% reduction in treatment failures at 28 days,” said Barry Quart, PharmD, CEO and director, Connect Biopharma.^¹

Connect Biopharma expects topline results from its companion Seabreeze STAT COPD trial (CBP-201-207) later in September 2026, ahead of planned FDA engagement on a phase 3 registrational program for rademikibart in acute exacerbations of asthma and COPD.^¹

References

1. Connect Biopharma. Connect Biopharma announces positive preliminary topline data from its global phase 2 study of rademikibart as an add-on treatment for acute exacerbations in adult and adolescent participants with asthma and type 2 inflammation. Published September 15, 2026. Accessed September 15, 2026. https://investors.connectbiopharma.com/news-releases/news-release-details/connect-biopharma-announces-positive-preliminary-topline-data

2. ClinicalTrials.gov. Rademikibart add-on treatment of an acute asthma exacerbation (Seabreeze STAT Asthma). Identifier: NCT06940141. Accessed September 15, 2026. https://clinicaltrials.gov/study/NCT06940141