The use of JAK inhibitors for low-risk myelofibrosis.

Myelofibrosis is a heterogeneous disorder, which, although sometimes asymptomatic in the early stages, is frequently associated with debilitating constitutional symptoms, poor quality of life and high degree of morbidity as the disease progresses. Ruxolitinib, a JAK1/2-inhibitor, has transformed the management of many patients by reducing disease-related symptoms and splenomegaly in intermediate-2 and high-risk patients. As demonstrated by the COMFORT studies, unprecedented clinical benefit can be gained by some patients on ruxolitinib; however, this is not without potential adverse effects, notably cytopenias, weight-gain and an increased risk of opportunistic infections. No other JAK inhibitors are currently approved for myelofibrosis. Moreover, long-term effects of JAK-inhibitor agents, such as ruxolitinib, remain unknown. Consequently, the use of ruxolitinib in the low-risk patient, in the absence of high symptom burden remains controversial and requires further randomized clinical trials. In such patients, an individualized approach should be adopted, balancing likely clinical benefit with the potential side-effect profile.