Connect Biopharma has pointed to phase 2 data for its IL-4/IL-13 blocker as proof that the wannabe Dupixent rival can reduce respiratory attacks—although the study missed a secondary endpoint tied to a breathing test.
The San Diego-based biotech evaluated rademikibart as an add-on to standard of care in the mid-stage Seabreeze STAT COPD study of 159 patients who have previously experienced an acute chronic obstructive pulmonary disease (COPD) exacerbation. These patients received either rademikibart or placebo.
The study’s primary endpoint focused on treatment failure within 28 days, which was defined by either death, or a COPD exacerbation that resulted in admission to hospital, a medical visit or increasing pharmacological treatment.
Within this four-week window, rademikibart led to an 81% reduction in the rate of treatment failure. Using the drug was also tied to an 85% reduction in the rate of new moderate-to-severe COPD exacerbations, the company noted.
The study missed a secondary endpoint evaluated by a breathing test called the post-bronchodilator forced expiratory volume in one second (FEV1) after seven days. However, the company pointed out that the 70 mL improvement in FEV1 at Week 4 was clinically meaningful.
Connect CEO Barry Quart homed in on the fact that no patients receiving rademikibart needed to attend hospital or an emergency department (ED) during the four-week period.
The data provided “overwhelming evidence of the potential benefit early treatment with rademikibart may provide to COPD patients experiencing an acute exacerbation,” the CEO said in a statement.
“2025 claims data indicate that COPD patients going to the ED due to an acute exacerbation generate approximately $6 billion in healthcare costs in the following 30 days due to return visits to the ED or hospital,” Quart explained in the release. “This study demonstrated that rademikibart completely eliminated those return visits while decreasing new moderate-to-severe COPD exacerbations by 85% compared to placebo.”
“These groundbreaking results provide a unique opportunity to differentiate rademikibart in COPD from all other approved biologics,” he added.
Rademikibart was well tolerated in COPD patients experiencing an acute exacerbation with a lower incidence of adverse events than placebo, the company noted in its Sept. 30 release.
The biotech plans to engage with the FDA “as soon as feasible” about a phase 3 program for rademikibart as an add-on treatment for COPD.
The COPD results come weeks after a Connect unveiled topline data from the sister Seabreeze STAT asthma study. While that study showed rademikibart was able to reduce the rate of treatment failure by 66% over 28 days compared to placebo, this was not enough to demonstrate statistical significance, which Connect blamed at the time on an “overall lower treatment failure rate than projected.”
Despite this FEV1 miss in this morning’s readout, Quart told investors on call that the company is still planning to suggest to the FDA that this breathing test is used as an endpoint of a proposed phase 3 trial for rademikibart in asthma.
“[For] COPD patients [it’s] much more challenging population to show FEV1 improvement,” the CEO added. “A lot of these patients are completely resistant to bronchodilators as well, and … we're in a situation where we're maximizing bronchodilator treatment right before we give drugs.”
Rademikibart is an anti-interleukin-4-receptor alpha (IL-4Rα) antibody that prevents the receptor from interacting with other receptor subunits that are required for activation of the signaling pathways that lead to asthma. Simcere Pharmaceuticals paid Connect $21 million upfront for the China rights to the drug, amid hopes the therapy could rival Sanofi and Regeneron's blockbuster asthma and COPD drug Dupixent.
Rademikibart’s biggest success to date was a phase 3 win in China for patients with atopic dermatitis, which Simcere reported back in March.