ATLANTA (FRONTLINE MEDICAL NEWS) – The use of dexpramipexole by patients with chronic rhinosinusitis was well tolerated and showed robust and tissue eosinophil–lowering activity, according to results from a small study.

Dexpramipexole is an investigational oral agent that has been studied in previous clinical trials for patients with amyotrophic lateral sclerosis, Calman Prussin, MD , said in an interview at the annual meeting of the American Academy of Allergy, Asthma, and Immunology. The drug did not meet the clinical endpoint for ALS patients, but its investigators noted that it lowered eosinophil counts by about 50%. “It was a serendipitous finding,” said Dr. Prussin, senior director of clinical and translational medicine for Pittsburgh-based Knopp Biosciences. “We do not have a mechanism of action, but we think it’s working on progenitor cells in the bone marrow.”

In an effort to determine if dexpramipexole lowers blood and tissue eosinophils in patients with chronic rhinosinusitis with nasal polyps, the researchers conducted an open-label trial in 20 patients who received the drug at a dose of 150 mg b.i.d. for 6 months. The study’s primary endpoints were change from baseline in total eosinophil counts and change from baseline in total polyp score. The mean age of patients was 44 years, 11 were female, and 13 were white.

In all, 16 of the 20 patients completed the trial. Dr. Prussin and his associates found that the baseline eosinophil count fell from 0.525 x 109/L to 0.031 x 109/L at 6 months, a reduction of 94% (P less than.001). “I don’t think any of us expected to see this,” he said, noting that the drug’s maximal eosinophil-lowering effect was maximal after 2 months. No reduction in total polyp score was observed.

Biopsies conducted in 12 of the patients revealed that polyp tissue eosinophilia was reduced from a mean of 233 to 5 eosinophils/high-powered field, a drop of 97% (P = .001). No serious drug-related adverse effects occurred. The most common adverse event was infection (50%), followed by respiratory symptoms (35%) and gastrointestinal disorders (20%).

Knopp Biosciences funded the study. Dr. Prussin is an employee of the company.


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