Hemostasis in patients with primary myelofibrosis treated with ruxolitinib

Abstract

Aim. To evaluate the effect of ruxolitinib therapy on hemostasis in patients with primary myelofibrosis (PMF).Materials and methods. 30 patients with PMF were examined, 16 of them received ruxolitinib (group 1) at the time of examination and 14 were untreated (group 2). The control group consisted of 30 healthy individuals. A complete blood count was performed, the platelets aggregation, the activity of Willebrand factor, factor VIII and natural anticoagulants were evaluated. In the thrombin generation test, the endogenous thrombin potential (ETP, nM×min) was determined; sensitivity to thrombomodulin and coagulation index were calculated. Kruskal-Wallis test with post hoc Dunn test was used to compare groups.Results. Hemoglobin and platelet count were lower in group 1 compared to group 2 and control. Platelet aggregation with collagen was lower in patients with PMF than in the control group, and lower in group 1 than in group 2: 2.2 (1.6; 5.7) % vs 41.6 (3.4; 64.8) %, p < 0.05. In patients in group 1, the activity of Willebrand factor – 150.0 (122.5; 195) % and factor VIII – 173 (148.5; 200) % was higher (p < 0.05) than in the control: 97 (84.8; 110) % and 104 (85; 130) % respectively. Antithrombin did not differ in the PMF and control group. Protein S was reduced in both groups with PMF: group 1 – 70 (58; 86,6) %, group 2 – 65 (43,6; 107,5) %, control – 102 (86; 109,0) %, p < 0.001. ETP and sensitivity to thrombomodulin in groups 1 and 2 were low, p < 0.001. The coagulation index tended to higher values than in the control: 5.3 (3.0; 11.4) – group 1; 3.2 (2.4; 7.3) – group 2; control – 1.9 (1.6; 2.2), p = 0.073.Conclusion. Ruxolitinib therapy leads to the failure of the platelet hemostasis, the procoagulant activity of plasma with an increase in the activity of Willebrand factor and factor VIII and a decrease in the activity of protein S.