(HealthDay News) – For patients with myelofibrosis, treatment with a potent and selective Janus kinase 1 and 2 inhibitor, ruxolitinib, provides significant clinical benefit compared with the best available treatment or placebo, according to two studies published in the March 1 issue of the New England Journal of Medicine.

Claire Harrison, DM, from Guy’s Hospital in London, and colleagues compared ruxolitinib with the best available therapy for 219 patients with intermediate-2 or high-risk primary myelofibrosis. The researchers found that 32% and 0% of the ruxolitinib and best available therapy groups, respectively, had at least a 35% reduction in spleen volume at 24 weeks (P<0.001); 28% and 0%, respectively, had at least a 35% reduction in spleen volume at 48 weeks (P<0.001).

Srdan Verstovsek, MD, PhD, from the University of Texas MD Anderson Cancer Center in Houston, and colleagues randomly assigned patients with intermediate-2 or high-risk myelofibrosis to oral ruxolitinib (155 patients) or placebo (154 patients) in a double-blind, placebo-controlled trial. The researchers found that the proportion of patients with a reduction in spleen volume of 35% or more at 24 weeks was 41.9% of patients in the ruxolitinib group versus 0.7% in the placebo group (P<0.001). Of the patients with a response to ruxolitinib, 67% had the response for 48 weeks or more. The total symptom score improved by 50% or more for 45.9% of patients receiving ruxolitinib versus 5.3% of patients receiving placebo (P<0.001).

“Ruxolitinib, as compared with placebo, provided significant clinical benefits in patients with myelofibrosis by reducing spleen size, ameliorating debilitating myelofibrosis-related symptoms, and improving overall survival,” Verstovsek and colleagues write.

The Harrison study was funded by Novartis. Several authors from the Verstovsek study disclosed financial ties to pharmaceutical companies, including Incyte, which funded the study and manufactures ruxolitinib.

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