Abstract
Hydroxyurea is the preferred first-line cytoreductive treatment for high-risk essential thrombocythaemia (ET), but many patients are intolerant or refractory to hydroxyurea. Ruxolitinib has been shown to improve symptoms in patients with ET. This post hoc analysis compared the clinical outcomes of patients with ET who received hydroxyurea only with those who switched from hydroxyurea to ruxolitinib due to intolerance/resistance to hydroxyurea. Patients with ET refractory/intolerant to hydroxyurea treated with ruxolitinib in a completed phase 2 study (HU-RUX) were propensity score matched with patients who received hydroxyurea only in an observational study (HU). Changes in leukocyte and platelet counts were reported at 6-month intervals during the 48-month follow-up. Following propensity score matching, 37 patients were included for analysis in each cohort. Mean (standard deviation [SD]) leukocyte and platelet counts at index were higher for HU-RUX versus HU (leukocyte: 9.3 [5.1] vs. 6.8 [3.1] × 10(9)/L; platelet: 1027.4 [497.8] vs. 513.9 [154.7] × 10(9)/L), both of which decreased significantly from index to 6 months through to 48 months in HU-RUX (mean [SD] change from index at 6 months-leukocyte: -1.8 [4.6] × 10(9)/L; platelet: -391.7 [472.9] × 10(9)/L; at 48 months-leukocyte: -3.8 [5.3] × 10(9)/L; platelet: -539.0 [521.8] × 10(9)/L), but remained relatively stable in HU (mean [SD] change from index at 6 months-leukocyte: 0 [1.8] × 10(9)/L; platelet: -5.7 [175.3] × 10(9)/L; at 48 months-leukocyte: -0.1 [2.7] × 10(9)/L; platelet: -6.9 [105.1] × 10(9)/L). In conclusion, these results demonstrate that switching from hydroxyurea to ruxolitinib in patients with ET who are intolerant or refractory to hydroxyurea could improve abnormal haematologic values similar to those who receive first-line hydroxyurea.