Connect Biopharma COPD Study Shows 81% Cut in Treatment Failures

Key Points

• Rademikibart reduced treatment failures by 81% versus placebo in Connect Biopharma’s Phase II COPD study, while new moderate-to-severe exacerbations fell 85%. No treatment-failure-related hospitalizations or emergency-department visits occurred among treated patients, compared with seven in the placebo group.
• The drug missed its day-seven FEV1 endpoint, though it produced a 70 mL improvement at week four, reduced rescue-inhaler use and improved COPD symptom scores. The FEV1 benefit was no longer evident by week eight.
• Connect reported generally favorable safety results and plans to consult the FDA on Phase III development, while advancing an intravenous formulation for hospital and emergency-department use and seeking a partner for broader COPD commercialization.

Connect Biopharma NASDAQ: CNTB reported top-line results from its Seabreeze STAT Phase II study of rademikibart in patients experiencing acute exacerbations of chronic obstructive pulmonary disease, or COPD. The company said the study met its primary objective, showing reductions in treatment failures during the month after an exacerbation.

Barry Quart, Connect Biopharma’s chief executive officer and director, said rademikibart produced an 81% reduction in treatment failures versus placebo, with a p-value of 0.0122. The company also reported an 85% reduction in new moderate-to-severe exacerbations, with a p-value of 0.0301, and no emergency department visits or hospital admissions among rademikibart-treated patients for treatment failures during the study period.

The randomized study enrolled 159 patients after screening 325 individuals. Eighty-one patients received placebo and 78 received rademikibart. Quart said the study used a design and entry criteria similar to the ABRA study in the United Kingdom, which evaluated benralizumab in patients with asthma and COPD exacerbations.

Hospital and Emergency Department Outcomes

In the placebo group, seven treatment failures resulted in either hospitalization or an emergency department visit, compared with none in the rademikibart group. Connect said the difference was statistically significant, with a p-value of 0.0137. The company said treatment failures in the study could also include unscheduled medical visits or intensification of pharmacologic therapy.

A Kaplan-Meier analysis showed separation between the treatment arms beginning about two weeks after treatment and widening through four weeks, according to Quart. The company reported that rademikibart-treated patients had two unscheduled medical visits, while no hospitalizations or emergency department visits were recorded for treatment failures in that arm.

Quart said recent 2025 claims data compiled by Komodo Health indicated there were approximately 1.6 million emergency department visits in the United States involving acute COPD exacerbations among type 2 high, or T2-high, patients. The company estimated that costs for care in the 30 days following these index exacerbations totaled roughly $6 billion in 2025.

Connect said it believes early rademikibart treatment could reduce a portion of those return-care costs, though the company’s comments reflected its interpretation of the trial results and claims analysis.

FEV1 Endpoint Missed, Week-Four Improvement Reported

The study did not meet its secondary endpoint for improvement in forced expiratory volume in one second, or FEV1, at day seven. Quart said both the placebo and rademikibart groups improved by approximately 120 milliliters during the first week following bronchodilator treatment.

However, the company reported a clinically meaningful 70 mL improvement in FEV1 at week four after a single rademikibart dose. Quart said the benefit was no longer evident by week eight.

Connect also reported a significant reduction in rescue-inhaler use by week two that was maintained through week seven. In addition, the company said rademikibart significantly improved scores on the Exacerbation of Chronic Pulmonary Disease Tool, or EXACT-PRO, by week one, with differences continuing through week four.

Safety and Regulatory Planning

Quart described the safety findings as “unremarkable,” saying adverse events and serious adverse events were less frequent in the rademikibart group than in the placebo group. One patient randomized to rademikibart died 37 days into the study, which Quart said was unrelated to treatment. He also noted that one death occurred during screening before randomization.

During the question-and-answer session, Quart said Connect continues to prioritize an acute asthma program, where it expects FEV1 to remain a potential registrational endpoint. The company plans to meet with the U.S. Food and Drug Administration later this year to discuss a Phase III acute asthma program.

For acute COPD, Quart said Connect will discuss potential endpoints with the FDA, including treatment failure, exacerbation measures and potentially an area-under-the-curve FEV1 approach. He said COPD patients can be more difficult to assess using FEV1 because they may have limited responsiveness to bronchodilators.

Connect also said it has begun developing an intravenous formulation of rademikibart for use in emergency department and hospital settings. The company is conducting an ongoing Phase II study of the IV formulation in a larger population of patients with asthma and COPD exacerbations and expects to gather additional information through the year.

Quart said Connect intends to advance the acute asthma program with its own capital while pursuing a potential commercial partnership or other transaction that could support COPD development. The company does not intend to separate commercial rights for the asthma and COPD programs, he said, and would seek a partner capable of commercializing rademikibart across both indications outside Greater China.

About Connect Biopharma (NASDAQ:CNTB)

Connect Biopharma Holdings Limited NASDAQ: CNTB is a clinical-stage biopharmaceutical company focused on developing therapies for chronic inflammatory and immune-mediated diseases. The company's research is based on insights into T-cell biology and aims to address conditions with significant unmet medical needs, including inflammatory bowel disease and dermatological disorders.

Connect Biopharma's pipeline has included CBP-201, an antibody targeting the interleukin-4 receptor alpha pathway, and CBP-307, an oral sphingosine-1-phosphate receptor modulator.

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