Hydroxyurea does not appreciably reduce JAK2 V617F allele burden in patients with polycythemia vera or essential thrombocythemia.

Conflicting results about the effects of hydroxyurea on the burden of mutant allele in patients with myeloproliferative neoplasms (MPN) harboring the JAK2V617F mutation have been produced recently. Owing to these conflicting results, the aim of our study was to analyze changes of JAK2V617F allele burden occurring during long-term follow-up in 172 patients with PV or ET and the relationships with hydroxyurea treatment. We conclude that in untreated patients with ET and PV changes in V617F allele burden occur very smoothly over years and we failed to confirm previous reports supporting the effectiveness of hydroxyurea in reducing the burden of JAK2V617F allele.