Efficacy and safety of ruxolitinib in intermediate-1 IPSS risk myelofibrosis patients: Results from an independent study

Patients with myelofibrosis at intermediate-1 risk according to the International Prognostic Score System are projected to a relatively long survival; nonetheless, they may carry significant splenomegaly and/or systemic constitutional symptoms that hamper quality of life and require treatment. Since registrative COMFORT studies included only patients at intermediate-2/high International Prognostic Score System risk, safety and efficacy data in intermediate-1 patients are limited. We report on 70 intermediate-1 patients treated with ruxolitinib according to standard clinical practice that were evaluated for response using the 2013 IWG-MRT criteria. At 6 months, rates of spleen and symptoms response were 54.7% and 80% in 64 and 65 evaluable patients, respectively. At 3 months, ruxolitinib-induced grade 3 anemia and thrombocytopenia occurred in 40.6% and 2.9% of evaluable patients, respectively. Notably, 11 (15.9%) patients experienced at least one infectious event ≥grade 2. Most (82.6%) patients were still on therapy after a median follow-up of 27 months. These data support the need for standardized guidelines that may guide the decision to initiate ruxolitinib therapy in this risk category, balancing benefit expectations and potential adverse effects.