Cytoreduction and JAK Inhibitors Associated With Fewer Thrombotic Events in Post-Polycythemia Vera and Post-Essential Thrombocythemia Myelofibrosis

Both conventional cytoreduction and JAK inhibitors were associated with fewer thrombosis in patients with post-polycythemia vera and post-essential thrombocythemia myelofibrosis, according to a recent study published in Leukemia.

“Patients with Philadelphia-negative myeloproliferative neoplasms are at high risk of thrombotic events,” wrote Barbara Mora, MD, University of Insubria, Varese, Italy, and colleagues. “Predisposing factors have been identified in essential thrombocythemia, polycythemia vera and primary myelofibrosis, while yet not recognized in post polycythemia vera/[essential thrombocythemia-secondary myelofibrosis].”

Using the Myelofibrosis SECondary to PV and ET (MYSEC) database, this study included 1258 patients with secondary myelofibrosis from 19 senters across Europe, the United States, and Australia. Using this cohort, study authors aimed to assess the incidence of thrombosis in patients with secondary myelofibrosis.

At a median follow-up of 3.5 years after the evolution of secondary myelofibrosis, 135 (10.7%) patients developed a thrombotic event, with an incidence of 2.3% patients per year. Venous events accounted for 2/3 of the total.

A Cox multivariable analysis, supported by Fine-Gray models with death as competitive risk, revealed that being on cytoreductive therapy at the time of secondary myelofibrosis evolution was associated with an absolute risk reduction of thrombosis equal to 3.3% within 3 years.

According to univariate regression model, conventional cytoreduction (mainly hydroxyurea; hazard ratio [HR] 0.41; 95% confidence interval [CI], 0.26 to 0.65, P = .0001) and JAK inhibitors (mainly ruxolitinib; HR 0.50; 95% CI, 0.24 to 1.02; P = .05) were associated with fewer thrombosis events.

“Our study informs treating physicians of a non-low incidence of [thrombotic events] in post [polycythemia vera/essential thrombocythemia-secondary myelofibrosis] and of the potential protective role of cytoreductive therapy in terms of thrombotic events,” Dr Mora and colleagues concluded. 

Source:

Mora B, Guglielmelli P, Kuykendall A, et al. Prediction of thrombosis in post-polycythemia vera and post-essential thrombocythemia myelofibrosis: a study on 1258 patients. Leukemia. Published online August 30, 2022. doi:10.1038/s41375-022-01673-3