Early Response and Long-Term Outcomes of Ruxolitinib Therapy in Myelofibrosis: Multicenter Retrospective Study in 10 Centers of the Russian Federation

Abstract

Aim. To assess the efficacy of targeted therapy with ruxolitinib in patients with myelofibrosis in real clinical practice in Russia. To determine the prognostic value of spleen reduction in the early stages of ruxolitinib treatment and its effect on overall survival. Materials & Methods. The present retrospective study was based on the data of 10 centers of Russia. It included 56 myelofibrosis (primary or post-polycythemic and post-throm-bocythemic) patients who received ruxolitinib. The median age of patients was 56 years (range 26-76 years). Most of them (59 %) were considered intermediate-1 risk according Results. By the start of data collection most of patients (79 %) had been treated with ruxolitinib. In no case therapy was withdrawn for the reason of drug toxicity. On ruxolitinib constitutional symptoms were reversed in 70 %, 87 %, and 98 % of patients by months 1, 3 and 6, respectively. In 36 % and 46 % of patients by months 3 and 6, respectively, > 50 % decrease in spleen size was observed. Overall, in 31 % and 27 % of cases the size of the spleen decreased by less than 25 % by months 3 and 6, respectively. The factors affecting the changes in spleen size have not been identified. The probability of overall survival by years 2 and 5 of follow-up was 97 % and almost 70 %, respectively. This parameter was significantly affected by the extent of spleen size reduction by month 3 of follow-up as well as by its initial size. Conclusion. Ruxolitinib shows high efficacy for both decrease of general myelofibrosis symptoms and reduction in spleen size. The extent of spleen reduction is an important prognostic factor. It seems, that in patients with insufficient spleen reduction an increase in drug dose is advisable. If it is not possible, alternative methods of treatment should be sought.