Pacritinib With Standard of Care Azacitidine or Decitabine as a Bridge to Allogeneic Hematopoietic Stem Cell Transplant for Patients With Accelerated and Blast Phase Myeloproliferative Neoplasms

Inclusion Criteria: * Age ≥ 18 years * History of myeloproliferative neoplasms (MPN) as defined by the 2016 and 2022 World Health Organization criteria, with now pathologically confirmed ≥ 5% blasts in the bone marrow or peripheral blood. Prior MPNs could include polycythemia vera, essential thrombocythemia, primary myelofibrosis, secondary myelofibrosis, MPN-unclassifiable, and myelodysplastic syndrome (MDS)/MPN overlap syndromes * Outside diagnostic material is acceptable. Internal review at the study institution of outside peripheral blood and/or bone marrow slides is recommended. Flow cytometric analysis of peripheral blood and/or bone marrow should be performed according to institutional practice guidelines * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 OR Karnofsky ≥ 60% * Serum creatinine clearance ≥ 50 ml/min calculated by the Cockcroft-Gault Equation (assessed within 14 days of study day 1) * Total bilirubin ≤ 3 (total bilirubin \> 3 is allowable if thought due to Gilbert's disease, hemolysis, or MPN disease) (assessed within 14 days of study day 1) * Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) \< 3 x upper limits of normal (ULN) (total bilirubin \> 3 is allowable if thought due to Gilbert's disease, hemolysis, or MPN disease) (assessed within 14 days of study day 1) * Patient is considered a potential transplant candidate. The attending/treating physician will determine transplant candidacy at the time of consent * Intention …