Optimizing management of ruxolitinib in patients with myelofibrosis: the need for individualized dosing

Ruxolitinib, an oral JAK1 and JAK2 inhibitor, is approved in the US for patients with intermediate or high-risk myelofibrosis (MF), a chronic neoplasm associated with aberrant myeloproliferation, progressive bone marrow fibrosis, splenomegaly, and burdensome symptoms. Phase III clinical studies have shown that ruxolitinib reduces splenomegaly and alleviates MF-related symptoms, with concomitant improvements in quality of life measures, for the overwhelming majority of treated patients. In addition, ruxolitinib provided an overall survival advantage as compared with either placebo or what was previously considered best available therapy in the two phase III studies. The most common adverse events with ruxolitinib treatment include dose-dependent anemia and thrombocytopenia, which are expected based on its mechanism of action. Experience from the phase III studies shows that these hematologic events can be managed effectively with dose modifications, temporary treatment interruptions, as well as red blood cell transfusions in the case of anemia and, importantly, are rarely cause for permanent treatment discontinuation. This review summarizes data supporting appropriate individualized patient management through careful monitoring of blood counts and dose titration as needed in order to maximize treatment benefit.