RESUMEN
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] × 109/L; platelet: 1027.4 [497.8] vs. 513.9 [154.7] × 109/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] × 109/L; platelet: -391.7 [472.9] × 109/L; at 48 months-leukocyte: -3.8 [5.3] × 109/L; platelet: -539.0 [521.8] × 109/L), but remained relatively stable in HU (mean [SD] change from index at 6 months-leukocyte: 0 [1.8] × 109/L; platelet: -5.7 [175.3] × 109/L; at 48 months-leukocyte: -0.1 [2.7] × 109/L; platelet: -6.9 [105.1] × 109/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.
RESUMEN
ABSTRACT: Ruxolitinib reduces spleen volume, improves symptoms, and increases survival in patients with intermediate- or high-risk myelofibrosis. However, suboptimal response may occur, potentially because of signaling via the phosphoinositide 3-kinase (PI3K)/protein kinase B pathway. This phase 2 study evaluated dosing, efficacy, and safety of add-on PI3Kδ inhibitor parsaclisib for patients with primary or secondary myelofibrosis with suboptimal response to ruxolitinib. Eligible patients remained on a stable ruxolitinib dose and received add-on parsaclisib 10 or 20 mg, once daily for 8 weeks, and once weekly thereafter (daily-to-weekly dosing; n = 32); or parsaclisib 5 or 20 mg, once daily for 8 weeks, then 5 mg once daily thereafter (all-daily dosing; n = 42). Proportion of patients achieving a ≥10% decrease in spleen volume at 12 weeks was 28% for daily-to-weekly dosing and 59.5% for all-daily dosing. Proportions of patients achieving ≥50% decrease at week 12 in Myelofibrosis Symptom Assessment Form and Myeloproliferative Neoplasms Symptom Assessment Form symptom scores were 14% and 18% for daily-to-weekly dosing, and 28% and 32% for all-daily dosing, respectively. Most common nonhematologic treatment-emergent adverse events were nausea (23%), diarrhea (22%), abdominal pain and fatigue (each 19%), and cough and dyspnea (each 18%). New-onset grade 3 and 4 thrombocytopenia were observed in 19% of patients, each dosed daily-to-weekly, and in 26% and 7% of patients dosed all-daily, respectively, managed with dose interruptions. Hemoglobin levels remained steady. The addition of parsaclisib to stable-dose ruxolitinib can reduce splenomegaly and improve symptoms, with manageable toxicity in patients with myelofibrosis with suboptimal response to ruxolitinib. This trial was registered at www.clinicaltrials.gov as #NCT02718300.