ASH Clinical News September 2015 | Page 49

CLINICAL NEWS With Prolonged Treatment, Ruxolitinib Lessens JAK2 V617F Allele Burden in Patients with Myelofibrosis A high proportion of patients with BCR-ABL1-negative myeloproliferative neoplasms (myelofibrosis, essential thrombocythemia, and polycythemia vera) have the JAK2 V617F mutation, which can lead to constitutive JAK2 activity and contribute to dysregulated JAK signaling in clonal cells. In the COMFORT-I trial, use of the oral JAK1/JAK2 inhibitor ruxolitinib led to durable reductions in splenomegaly and improvements in disease-related symptoms, which led to FDA approval of ruxolitinib for patients with intermediate-2 or high-risk myelofibrosis in November 2011. ”Patients originally randomized to [receive] ruxolitinib had prolonged survival and greater reductions in spleen volume versus patients who crossed over from placebo.” —MICHAEL DEININGER, MD, PhD Previous studies have suggested that ruxolitinib effects th