An Exploratory Study on the Use of Gecacitinib in Patients With Myeloid Malignancies and Myelofibrosis During the Peri-transplant Period Following Allogeneic Hematopoietic Stem Cell Transplantation

Prior treatment

• Currently receiving JAK inhibitors other than gecacitinib at screening (patients who have switched from other JAK inhibitors to gecacitinib before screening are eligible)
• Prior allogeneic hematopoietic stem cell transplantation or organ transplantation
• Any of the following within 6 months before screening: NYHA class III-IV congestive heart failure, unstable angina, myocardial infarction, cerebrovascular accident, or pulmonary embolism; arrhythmia requiring treatment; or QTcB \>480 ms.
• Major surgery within 4 weeks before screening without full recovery
• Treatment with anticoagulant or antiplatelet drugs (except low molecular weight heparin)
• Participation in other investigational drug or medical device clinical trials within 3 months before screening

Other illness

• Uncontrolled severe infection, shock, severe organ failure, or any other condition that would preclude tolerance of the study treatment at enrollment.
• Known active gastrointestinal ulcer at screening, or a history of gastrectomy or intestinal resection that may affect drug absorption.
• Known HIV infection and/or AIDS
• History of tuberculosis infection
• Epilepsy or use of psychotropic/sedative drugs at screening
• Any other comorbidity that may affect the study or prior malignancy
• Other severe conditions that, in the investigator's judgment, may affect patient safety or compliance
• Known hypersensitivity to gecacitinib hydrochloride, drugs of the same class, or any excipients
• Any comorbidity or prior malignancy that, in the investigator's judgment, may affect study participation, safety evaluation, or interpretation of study results.

Lab values

• Any significant clinical or laboratory abnormality that may affect safety evaluation, including:
  • Uncontrolled diabetes (fasting blood glucose \>13.9 mmol/L)
  • Uncontrolled hypertension despite ≥2 antihypertensive drugs (SBP ≥160 mmHg or DBP ≥100 mmHg)
  • Peripheral neuropathy (NCI-CTC AE v5.0 grade ≥2)
  • Serum creatinine \>1.5×ULN
  • ALT or AST \>2.5×ULN; DBIL or TBIL \>2.0×ULN

Other

• Pregnant or breastfeeding women; patients unable to use effective contraception throughout the study period

• Patients must voluntarily sign the informed consent form, be aged ≥18 years at the time of informed consent, and may be of either sex.
• Diagnosed with myeloid neoplasms according to 2022 WHO diagnostic criteria
• Bone marrow fibrosis grade ≥2 according to 2016 WHO myelofibrosis grading criteria
• Undergoing first allogeneic hematopoietic stem cell transplantation
• ECOG performance status: 0-2
• Able to swallow tablets
• Able to comply with study procedures and follow-up requirements