Frequent reduction or absence of detection of the JAK2-mutated clone in JAK2V617F-positive patients within the first years of hydroxyurea therapy

Abstract Objective: To analyse the effect of hydroxyurea (HU) on the JAK2-V617F allelic ratio (%JAK2-V617F) of patients with Polycythaemia Vera (PV) and Essential Thrombocythaemia (ET). Methods: Thirty-six patients were examined sequentially prior to and after on-set of (HU) therapy (8 PV, 17 ET), or while remaining untreated (2 PV, 9 ET). For all patients, the %JAK2-V617F was determined in purified blood granulocytes using sensitive allele-specific, quantitative PCRs. In a second study, two distinct groups of patients were examined at a single time point at the time of diagnosis (99 PV, 178 ET) or while receiving HU (36 PV, 98 ET). Results: HU therapy (median duration: 15 months) reduced t…