CLINICAL AND MOLECULAR GENETIC CHARACTERISTICS OF POLYCYTHEMIA VERA AND CURRENT TREATMENT APPROACHES

According to the 2008 WHO diagnostic criteria, there should be 2 major and 1 minor criteria for the diagnosis of polycythemia vera (PV). However, in some patients, due to low hemoglobin (HGB), patients were excluded from the diagnosis and were not prescribed timely treatment. So, there was a need to divide patients into 2 clinical forms: overt and masked, and to analyze both of them.

To identify overt and masked forms of PV; to investigate thrombotic risk groups, thromboembolic events (TE), allel burden (AB) of the JAK2V617F gene and various therapeutic methods in overt PV (oPV) and masked PV (mPV) according to the thrombotic risk groups.

Cohort study (retrospective and prospective components).

209 PV patients were selected and divided into 2 clinical forms. The hemogram parameters, AB, risk group and TE in each clinical form were studied and compared. Out of 209 patients, 101 were selected and treated due to the clinical forms and thrombotic risk groups. The hematologic responce (HR) was analysed according to the risk group and clinical form of the disease.

Out of 209 patients oPV was detected in 136, mPV in 73. In comparison oPV to mPV, HGB, erithrocyte counts, and hematocrit (HCT) were higher, while platelets (PLT) were lower and no statistically significant difference was noted in white blood cells counts. In oPV, 68 (50.0%) patients were in low risk group (LRG), 68 (50.0%) in high risk group (HRG), and in mPV, 44 (60.3%) in LRG, and 29 (39.7%) in HRG. TE were more common in mPV compared to oPV (p<0.01). The JAK2V617F AB differed significantly between oPV and mPV within the LRG (p=0.001). In contrast, no significant differences were observed in the HRG across AB categories (p=0.24). Within LRG, higher ABs (26-100%) were more frequent in oPV than mPV. In HRG, the distribution of AB was similar between groups, with no statistically significant differences. HGB and HCT were lower in all quartiles in mPV compared to oPV. Out of 101 PV patients, mPV demonstrated significantly higher overall HR rates compared to oPV (p = 0.003). Within the LRG treated with phlebotomy+low dose aspirin, mPV showed superior response compared to oPV (p=0.007). In the HRG treated with hidroxiurea, mPV also had better response than oPV (p=0.011). No statistically significant difference was observed in high-risk patients treated with interferon between oPV and mPV (p=0.200).

More patients were included in the HRG during oPV. However, TE were more common in mPV. It seems that the occurrence of TE is related to the delay in diagnosis of mPV and the lack of timely and intensive treatment. This situation can also be attributed to the role of other factors in the occurrence of thrombosis. It is no coincidence that the PLT count was higher in mPV compared to oPV. Treatment of mPV is more effective than oPV. This once again demonstrates the importance of timely and active treatment of mPV.