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First-line hydroxyurea may be effective in polycythemia vera, essential thrombocythemia
Besses C. Br J Haematol. 2011;152:413-419.
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More than half of patients with polycythemia vera and essential thrombocythemia experienced partial molecular response after treatment with hydroxyurea, according to study results.
Researchers from several sites in Barcelona, Spain, prospectively analyzed the modulation of JAK2 V617F allele burden dynamics in 47 patients — 26 with polycythemia vera and 21 with essential thrombocythemia — who were treated with first-line hydroxyurea. The JAK2 V617F dynamics in this group were compared with those in a control group of 21 polycythemia vera patients and 24 essential thrombocythemia patients.
Hydroxyurea was administered at a mean daily dose of 958 ± 206 mg in polycythemia vera patients and 968 ± 251 mg in essential thrombocythemia patients.
The partial molecular response rate — as defined by European LeukemiaNet criteria — was 57% in the treatment group. The median duration required to reach partial molecular response was 14 months (range 3-66 months). The probability of partial molecular response at 3 years was 57%.
Patients with a hematocrit level ≥ 0.45 L/L were more likely to achieve a partial molecular response (HR=3.4; 95% CI, 1.02–11.6). This trend held after multivariate analysis, including age and leukocyte count (HR for hematocrit ≥0.45 L/L=3.36; 95% CI, 0.97–11.6). The trend was not significant for the remaining variables.
Patients in the treatment group with both diseases experienced significant decreases in JAK2 V617F allele load at 36 months. The allele load reduction was higher in polycythemia vera patients than in essential thrombocytopenia patients (P=.01).
A slight but not significant increase in JAK2 V617F allele burden was observed in the control group over time.
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