Impact of and V617F Mutations on Clinical Course and Disease Outcomes in Essential Thrombocythemia: A Multicenter Retrospective Study in Turkish Patients.

OBJECTIVE

In this study, we investigated the effects of calreticulin () and V617F mutational status on clinical course and disease outcomes in Turkish patients with essential thrombocythemia (ET).

MATERIALS AND METHODS

Seventeen centers from Türkiye participated in the study and - and V617F-mutated ET patients were evaluated retrospectively.

RESULTS

A total of 302 patients were included, of whom 203 (67.2%) and 99 (32.8%) were V617F- and -positive, respectively. -mutated patients were significantly younger (51 years vs. 57.5 years, p=0.03), with higher median platelet counts (987x10/L vs. 709x10/L, p<0.001) and lower median hemoglobin levels (13.1 g/dL vs. 14.1 g/dL, p<0.001) compared to V617F-mutated patients. Thromboembolic events (TEEs) occurred in 54 patients (17.9%), 77.8% of which were arterial. Compared to mutation, V617F was associated with a higher risk of thrombosis (8.1% vs. 22.7%, p=0.002). Rates of transformation to myelofibrosis (MF) and leukemia were 4% and 0.7%, respectively, and these rates were comparable between V617F- and -mutated cases. The estimated overall survival (OS) and MF-free survival of the entire cohort were 265.1 months and 235.7 months, respectively. OS and MF-free survival durations were similar between V617F- and -mutated patients. Thrombosis-free survival (TFS) was superior in -mutated patients compared to V617F-positive patients (5-year TFS: 90% vs. 71%, respectively; p=0.001). Age at diagnosis was an independent factor affecting the incidence of TEEs.

CONCLUSION

In our ET cohort, mutations resulted in higher platelet counts and lower hemoglobin levels than V617F and were associated with younger age at diagnosis. V617F was strongly associated with thrombosis and worse TFS. Hydroxyurea was the most preferred cytoreductive agent for patients with high thrombosis risk.