Ruxolitinib First Drug Indicated for Myelofibrosis
Applying its priority review procedure, the FDA approved ruxolitinib (Jakafi, Incyte), an oral inhibitor of the Janus kinase (JAK) 1 and 2 gene, for the treatment of intermediate- and highrisk myelofibrosis (MF), including primary MF, postpolycythemia vera MF, and postessential thrombocythemia MF. Ruxolitinib is the first drug approved specifically for this indication. Ruxolitinib received accelerated approval (ahead of its regulatory date).
“Jakafi represents another example of an increasing trend in oncology where a detailed scientific understanding of the mechanisms of a disease allows a drug to be directed toward specific molecular pathways,” said Richard Pazdur, MD, Director, FDA’s Office of Hematology and Oncology Products.
The approval was based on 2 randomized, controlled clinical trials involving 528 patients with splenomegaly who were resistant or refractory to MF therapies or were ineligible for allogeneic bone marrow transplantation.
The primary end point (a 35% reduction in spleen volume) was achieved by 42% of patients with ruxolitinib versus 1% with placebo after 24 weeks, and by 29% versus 0%, respectively, after 48 weeks in study 2. Furthermore, 46% of patients receiving ruxolitinib had ≥50% reduction in total symptom scores compared with only 5% of those receiving placebo (P <.001).
The most common adverse effects reported were thrombocytopenia, anemia, bruising, dizziness, and headache. Grade 3 drug reactions more common with ruxolitinib than with placebo included thrombocytopenia (13% vs 1%, respectively) and anemia (45% vs 19%). (November 16, 2011)