HealthDay News — Fostamatinib produces clinically meaningful responses in adults with immune thrombocytopenia (ITP), according a study published in the July issue of the American Journal of Hematology.

James Bussel, MD, from Weill Cornell Medicine in New York City, and colleagues conducted two parallel phase 3 trials in which patients with persistent/chronic ITP (median duration, 8.5 years) were randomized in a 2-to-1 ratio to fostamatinib (101 patients) or placebo (49 patients), at 100mg twice daily for 24 weeks, with a dose increase to 150 mg twice daily after four weeks in non-responders. 

The researchers found that stable responses occurred in 18% of patients on fostamatinib vs 2% on placebo. Forty-three percent of patients on fostamatinib and 14% on placebo achieved overall responses (defined as ≥1 platelet count ≥50,000/μL within the first 12 weeks on treatment). With the 100mg dosage, the median time to response was 15 days, and 83% responded within 8 weeks. Diarrhea, hypertension, nausea, dizziness, and alanine aminotransferase increase were the most common adverse events and were all more frequent with fostamatinib versus placebo. However, most adverse events were mild or moderate and resolved spontaneously or with medical management. 

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“Fostamatinib is a novel ITP treatment option that targets an important mechanism of ITP pathogenesis,” the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including Rigel Pharmaceuticals, which manufactures fostamatinib and funded the study.

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