Can a new pill shrink the spleen in myelofibrosis?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. The subjects voluntarily participated in this study after obtaining full informed consent and signed the informed consent form. 2. Age ≥18 years old, gender not limited; 3. Patients diagnosed with primary myelofibrosis (PMF) according to the 2016 World Health Organization (WHO) criteria, or patients diagnosed with post-essential thrombocythemia MF (PET-MF) or post-polycythemia vera MF (PPV-MF) according to International Working Group for Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria; 4. Patients evaluated as intermediate-1, intermediate-2, or high-risk according to the International Prognostic System (DIPSS) scoring system;; 5. Expected life expectancy is ≥ 24 weeks; 6. Eastern Cooperative Oncology Group (ECOG) score of 0-2 ; 7. No planned for stem cell transplantation in the near future. 8. Splenomegaly: Palpation of the spleen margin reaches or exceeds at least 5cm below the costal margin (the distance from the costal margin to the farthest point of the spleen protrusion), or spleen volume ≥450cm ³ by CT or MRI. 9. Adequate hematological and organ function within 7 days before the first administration of the study drug (no RBC transfusion, growth factors, colony-stimulating factors, platelet-generating factors ,or platelet transfusion within 14 days before the testing) : * Absolute neutrophil count (ANC) ≥1.5×109/L; * Platelet count ≥75×109/L(Phase IA); Platelet count ≥100×109/L(Phase IB); Hemoglobin ≥ 8.0g /dL; Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3.0× upper limit of normal (ULN); Total bilirubin ≤1.5×ULN; Creatinine ≤1.5×ULN. 10. For women of childbearing age, within 7 days before the first administration, if the serum pregnancy test is confirmed to be negative and they agree to use effective contraceptive measures during the study drug period and within 90 days after the last administration. For male subjects whose sexual partners are women of childbearing age, they must agree to take effective contraceptive measures during the use of the study drug and within 90 days after the last administration. Exclusion Criteria: * Peripheral blood blasts \>5% or Bone marrow blasts \>10%. * Previous treatment with XPO1 inhibitors. * Unable to cooperate with or unable to perform MRI or CT scans as deemed necessary by sponsor and investigator * Treatment with strong CYP3A inhibitors or inducers within 14 days prior to initial administration"