Determination of the Clonality Profile in Myeloproliferative Neoplasms and Association With the Thrombotic Complications (CLOJAK)

Myeloproliferative Neoplasms (MPN) are hematological malignancies associated with an increased risk of thrombosis. Although different cell types have been involved in these complications (platelets, red blood cells, leucocytes and endothelial cells), there do not exist any reliable biomarker to predict the thrombotic risk in MPN patients. While some studies suggested that the JAK2V617F allele burden measured in leukocytes was associated with the risk of thrombosis, other studies did not confirm these results. Besides, a recent work demonstrated that in some patients, the JAK2V617F allele burden measured in platelets and red blood cells was higher than the one determined in leukocytes. Moreover, some patients present JAK2V617F mutated endothelial cells, known as pro-thrombotic in in vitro and animal models. The CLOJAK project will search for an association between the thrombotic risk in MPN and the proportion of cells carrying the JAK2V617F mutation in erythroid cells and platelets or its presence in endothelial cells. The objective is to determine a clonality profile (i.e. the profile of repartition of the JAK2V617F allele burden in the different hematopoietic and endothelial lineages) associated with the occurrence of thrombosis in MPN patients. One hundred and twenty PV and ET patients will be studied at diagnosis. Their platelets, red blood cells, granulocytes and endothelial cells will be isolated. The JAK2V617F allele burden will be measured in these cells thanks to a digital PCR technic. An association between the clonality profile and the existence of a thrombosis at diagnosis, the MPN phenotype (PV or ET), the IPSET-thrombosis score and the type of thrombosis (venous, arterial, splanchnic) will be searched.