Pacritinib vs. Hydroxyurea in Advanced Proliferative Chronic Myelomonocytic Leukemia

Inclusion Criteria: * Diagnosis of CMML-1 (5th WHO classification), with \<10% bone marrow blasts on morphology and \<5% peripheral blood blasts. * Proliferative disease, defined as white blood cell count ≥13 × 10⁹/L. * Advanced disease, defined as at least one of the following features during screening: spleen palpable ≥5cm below the lower costal margin in the midclavicular line; TSS ≥20; or platelet count \<100 × 10⁹/L. For participants in whom spleen palpation is not feasible, an ultrasound exam may be performed for assessment of spleen craniocaudal length (length ≥12 cm by ultrasound is considered splenomegaly). * ECOG performance status ≤2. * Adequate organ function: AST and ALT ≤3 × ULN, total bilirubin ≤4 × ULN (≤8 × ULN in participants with Gilbert's syndrome), creatinine clearance \>30 mL/min, absolute neutrophil count ≥0.5 × 10⁹/L, PT and PTT ≤1.5 × ULN. * Women of child-bearing potential must have a negative serum pregnancy test within 7 days prior to enrollment and, along with male participants, must agree to use a highly effective method of contraception from the first dose through 90 days after the last dose. Exclusion Criteria: * Active malignancy diagnosed within the past 2 years, except for curatively treated non-invasive cancers (e.g., basal/squamous cell skin cancer, low-risk prostate cancer on stable endocrine therapy with PSA stable ≥3 months). * Allogeneic hematopoietic stem cell transplant within 12 months prior to enrollment, or requiring immunosupp…