CALR Mutation and Thrombotic Risk in Patients with Essential Thrombocytopenia

By Kerri Fitzgerald - Last Updated: February 8, 2021

The CALR mutation has prognostic value for the stratification of thrombotic risk in patients with essential thrombocytopenia (ET), according to a study published in the European Journal of Haematology.

Researchers retrospectively assessed 983 patients with ET diagnosed in Spanish and Polish hospitals. After a median 7.5 years of follow?up from diagnosis, 155 patients (15.8%) had one or more thrombotic event.

Five?year thrombosis?free survival (TFS) rate was 83.8% for patients with the JAK2 V617F mutation, 91.6% for those with CALR-type 1 mutation, and 93.9% for those with CALR?type 2 mutations (P=0.002).

TFS for venous thrombosis was lower in CALR?type 1 mutations (P=0.046), with there was no difference in TFS for arterial thrombosis. The cumulative incidence of thrombosis was significantly different when comparing patients with JAK2 V617F versus CALR?type 2 mutations. However, this associated was not observed between patients with JAK2 V617F versus CALR?type 1 mutations.

In multivariate logistic regression models, when adjusted by age, CALR?type 2 mutation was a statistically significant protective factor for thrombosis with respect to JAK2 V617F mutation (odds ratio, 0.45; P=0.04).