Influence of JAK2V617F Allele Burden on Hematological Response in the Treatment of Polycythemia Vera

Background. The presence of the JAK2V617F mutation is a major criterion in diagnostic of Polycythemia Vera (PV). The role of JAK2V617F allele burden in the progression of PV is not completely understood. The significance of this variable for the progression of the disease, complications development and response to therapy are still a big question mark.

Aim. To estimate the significance of the level of JAK2V617F allele burden in the treatment of PV.

Methods. Seventy-nine patients (pts), 48 females and 31 males, were included in the study. PV was diagnosed from 1980 to 2016. Median age was 61 years (range, 28 - 85), median of the observation period was 4.9 year (0,2 - 35 years). JAK2V617F allele burden was studied in all pts. Patients received therapy with phlebotomy (erythrocytapheresis), hydroxyurea, interferon-alpha or combined therapy. Hematological response to the therapy was evaluated according to ELN criteria[1]. Differences between the groups were assessed with the Mann-Whitney U test.

Results. Out of the 79 patients, complete hematological response (CHR) was achieved in 8 (10%) pts, partial response (PHR) in 48 (60.8%) pts, and no response was achieved (no response - NR) in 23 (29,2%) pts. The mean level of allele burden in the group of patients with PHR was 68%(CI 57%-79%), in that without response - 65%(CI 43%-86%), and in the group with CHR was 35% (CI 19%-50%). The JAK2V617F allele burden was significantly different between the groups with CHR and PHR (p<0,03). We also observed statistical trends (p<0,09) regarding differences between the groups with CHR and NR. The JAK2V617F allele burden by groups is shown in Figure 1. Consequently, patients who achieved CHR on treatment, had lower JAK2V617F allele burden compared to patients with PHR or NR to the therapy.

Conclusion. The level of JAK2V617F allele burden can be a predictive marker of a response to treatment of PV. An individual approach to each patient, including a detailed study of molecular factors, is the key to successful prevention of complications and ensuring positive outcomes.

[1] Barosi G, Birgegard G, Finazzi G, et al. Response Criteria for Essential

Thrombocythemia and Polycythemia Vera: Result of a European LeukemiaNet

(ELN) Consensus Conference. Blood. 2009 Mar 10

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The JAK2V617F allele burden levels in patients groups by treatment response.

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The JAK2V617F allele burden levels in patients groups by treatment response.

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