Dexpramipexole may be the most effective biologic drug available at this point when it comes to lowering eosinophil levels in both the blood and tissues of asthmatic patients. “Based on its safety profile and convenience,” it could be a good solution for many asthma patients who have both moderate and severe eosinophilic asthma, noted researchers at the 2017 Annual Meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI) in Atlanta, Georgia on March 4, 2017.
Asthmologists and immunologists have long been interested in biologic and biosimilar medications because their patients have sensitivities and allergies that prevent them from benefitting from “traditional” medications that might help them control their allergic and asthma-related symptoms. As early as 2015, AAAAI noted the importance of research based around determining whether or not it would even be “possible to predict the response of particular treatments based on an asthma patient’s individual characteristics of disease” because so many asthma patients have unique combinations of sensitivities in varying degrees of severity. The research presented at AAAAI in early March bodes well, both for biologics’ efficacy in treating patients with eosinophilic disorders and for physicians’ ability to use them with some degree of predictability on outcomes.
Research like this study, which delved into the efficacy of dexpramipexole, an oral biologic, also supports the broader concept that biologics and their “follow-ons,” biosimilars, may be particularly effective in treating patients with unique health conditions. In this study, the researchers focused on eosinophil-lowering effects of dexpramipexole in patients with an eosinophil-associated disease that is common among asthmatics: chronic rhinosinusitis with nasal polyps (CRWsNP). Eosinophils tend to inflame CRWsNP and are often present at extremely high levels in the polyp tissues as well as patients’ blood, making a viable eosinophil-limiting drug attractive for treating these patients, who often are already taking multiple medications and may not tolerate more conventional drugs. These patients often also experience loss of lung function due to elevated eosinophil levels and may not respond well, if at all, to inhaled corticosteroids.
“We found that dexpramipexole’s eosinophil-lowering activity was as great or greater than seen with current biologics,” reported lead researcher Calman Prussin, MD, head of clinical and translational medicine in immunology at Knopp Biosciences LLC. Knopp is developing dexpramipexole, which is currently in phase 2/3 clinical studies for its effects on hypereosinophilic syndromes and phase 2 clinical studies for its effects on eosinophilic asthma.
The study involved a total of 20 patients with a mean age of 43.9 years. Sixteen of those subjects completed the trial, which involved taking 300 mg/day of dexpramipexole over 6 months. The team evaluated baseline changes in peripheral blood eosinophil counts and in total polyp score (TPS), which involved calculating eosinophil levels in the tissues of the patients’ nasal polyps. Patients had symptoms of CRWsNP for at least 10 years, and 43.75% of the study group that followed the study through to completion had a history of aspirin sensitivity. This sensitivity and the results of the study, indicating that these patients tolerate dexpramipexole with relatively minor side effects, are significant since aspirin-sensitive patients often have more extensive eosinophil-related inflammation than those who do not have this sensitivity. Furthermore, according to the World Allergy Organization (WAO), the mechanics of aspirin sensitivity “are not immunological but…related to pharmacological properties of ASA and other NSAIDS,” making biologic treatment options that much more attractive for this subgroup of patients.
At the end of the study, all patients displayed eosinophil lowering in both blood and polyp tissue, but the overall polyp score, which involves the prevalence of polyps and the type of nasal obstructions they create, remained unchanged, implying that a primary benefit of the drug may not necessarily be in treating CRWsNP specifically, but rather in offering great “utility in eosinophilic asthma and other eosinophil diseases,” Prussin explained. Also notably, dexpramipexole treatments did not seem to elicit serious side effects. Although a number of patients did experience adverse events in the form of infections (10), respiratory issues (7), gastrointestinal disorders (4), metabolism and nutrition disorders (3), and musculoskeletal issues (3), none were rated “serious,” in and of itself notable in a population known for sensitivities and negative reactions to many medications. Seven of the 11 patients who had their polyps biopsied also demonstrated a 94% reduction in eosinophil levels in those tissues, indicating, said the research team, “the possibility that dexpramipexole may have direct activity on tissue eosinophil formation.”