GSK's Long-Acting Asthma Drug Halves Attacks in Phase 3, Boosting Blockbuster Hopes

GSK's long-acting asthma treatment, depemokimab, has demonstrated a significant reduction in asthma attacks in two phase 3 clinical trials, reinforcing the company's efforts to secure approval for the drug. Despite not meeting all secondary endpoints, the primary goal of reducing asthma exacerbations was achieved, providing a strong foundation for GSK's push toward regulatory approval.

In May, GSK announced that depemokimab, a monoclonal antibody that inhibits the binding of human interleukin-5 (IL-5) to its receptor, successfully met the primary endpoint in the pivotal SWIFT-1 and SWIFT-2 trials. The latest data, presented at the European Respiratory Society International Conference in Vienna, offer a deeper insight into the drug's efficacy. The pooled analysis from these trials, which included 760 adults and adolescents with severe asthma and type 2 inflammation, revealed that depemokimab reduced asthma exacerbations by 54% over 52 weeks compared to placebo. Additionally, the analysis showed a 72% reduction in clinically significant exacerbations that necessitated hospitalization or emergency department visits, one of the secondary endpoints.

However, the treatment did not perform as strongly on other secondary endpoints, which included measures of quality of life, asthma control, and lung function. According to Dr. Kaivan Khavandi, GSK’s global head of respiratory and immunology R&D, these outcomes were influenced by a “significant placebo response," which poses a challenge in demonstrating a treatment effect for patient-reported outcomes. Nonetheless, Khavandi emphasized that these secondary results do not alter GSK's strategy for depemokimab. He highlighted that preventing exacerbations is the most crucial clinical outcome, and achieving success in this area is a significant milestone.

The safety profile of depemokimab was comparable to that of the placebo, with 73% of participants in both the depemokimab and placebo groups in SWIFT-1, and 72% and 78%, respectively, in SWIFT-2, reporting adverse events (AEs). Importantly, no deaths or serious AEs were deemed related to the treatment.

GSK is positioning depemokimab as one of its 12 potential blockbuster drugs set for launch in the coming years, with expectations of generating peak-year sales of £3 billion ($3.9 billion) if approved. Given that IL-5 is a crucial protein for patients with type 2 inflammation—a condition associated with elevated levels of eosinophils, a type of white blood cell—depemokimab's mechanism of action holds promise. Notably, around 40% of patients on short-acting biologics for severe eosinophilic asthma discontinue their treatment within a year. In this context, GSK is betting on depemokimab's twice-yearly injection schedule to establish it as the first approved "ultra-long-acting biologic" with six-month dosing.

Khavandi explained that sustained suppression of type 2 inflammation, a key driver of asthma exacerbations, could alter the disease's trajectory. Extended dosing intervals may also address other barriers to optimal outcomes, such as adherence issues and frequent healthcare visits.

While Khavandi did not provide specifics on the timeline for regulatory submission, he confirmed that GSK is promptly moving to correspond with health authorities globally. Additionally, data from a late-stage study of depemokimab in chronic rhinosinusitis with nasal polyps is anticipated this year, which will be considered in GSK's coordinated submission strategy.