To apply Ivarmacitinib for the prevention of acute graft-versus-host disease (aGVHD) in HLA haploidentical transplantation, the incidence of grade II-IV aGVHD after prevention, the incidence of primary graft failure, the rate of GVHD-free relapse-free survival (GRFS) (12 months), the incidence of infection, the incidence of chronic graft-versus-host disease (cGvHD) (100 days - 1 year), treatment-related mortality, the incidence and severity of cytokine release syndrome (CRS), and the safety of the prevention regimen will be evaluated.

This project is a prospective, single-arm clinical study. It aims to apply Ivarmacitinib for the prevention of acute graft-versus-host disease (aGVHD) in patients with hematological malignancies undergoing HLA-mismatched transplantation. The primary objective is to observe the incidence of grade II-IV aGVHD after transplantation prevention. The secondary objectives include the incidence of primary graft failure, graft-versus-host disease-free and relapse-free survival (GRFS) at 12 months, the incidence of infection, the incidence of chronic graft-versus-host disease (cGvHD) within 100 days to 1 year, treatment-related mortality, the incidence and severity of cytokine release syndrome (CRS), and the safety assessment of the prevention regimen. This study is intended to provide a reference for the clinical application of Ivarmacitinib in transplantation. Therefore, this research is proposed to be conducted.

Inclusion Criteria:

• The patients have been clearly diagnosed with hematological malignancies, including acute myeloid leukemia, acute lymphocytic leukemia, chronic myeloid leukemia, myelodysplastic syndrome, non-Hodgkin's lymphoma, and Hodgkin's lymphoma. The planned treatment for these patients is myeloablative or reduced-intensity conditioning, followed by HLA half-matched stem cell transplantation.
• Has not received any systemic treatment, including extracorporeal photodynamic therapy (ECP)
• KPS>60% or ECOG PS 0-2
• Patients who have not received any other prophylactic immunosuppressive agents or aGVHD/cGVHD treatment are eligible
• The female subjects of childbearing age are willing to use a medically approved highly effective contraceptive method (such as intrauterine device, contraceptive pill or condom) during the study period and within 180 days after the last administration of the study drug; for male subjects whose partners are of childbearing age, they agree to use an effective contraceptive method during the study period and within 180 days after the last administration of the study drug

Exclusion Criteria:

• Pregnant women or women who are breastfeeding
• Absolute Neutrophil Count (ANC) < 1.0 x 109/L or Platelet Count < 50 x 109/L
• Uncontrolled active infections or active hepatitis B or hepatitis that requires antiviral treatment
• Human Immunodeficiency Virus (HIV) positive
• Uncontrolled concurrent diseases, including but not limited to persistent or active infections, autoimmune diseases, thrombosis, symptomatic congestive heart failure, unstable angina pectoris, unstable arrhythmias, or mental disorders/situations that would limit compliance with the study requirements
• There are severe respiratory system diseases, severe renal function impairment, clinically significant or uncontrolled heart diseases, unresolved cholestasis and liver diseases (not attributable to aGvHD). Diseases that interfere with coagulation or platelet function and/or current drug treatments
• Immunosuppressive doses of steroids. This does not exclude the use of steroids in subjects with adrenal cortical insufficiency
• The diagnosis was clear: chronic lymphocytic leukemia, marginal zone lymphoma (MALT type), smoldering multiple myeloma, etc., all being low-grade malignant/cancer-preventing blood tumors
• Patients who have been diagnosed with pre-transplantation digestive tract perforation and have a history of gastric or intestinal resection surgeries, etc., may have their drug absorption affected
• It is known that there may be allergic reactions, hypersensitivity reactions or intolerance to the studied drug or its excipients
• The researchers believe that there are any conditions that might harm the subjects or prevent them from fulfilling or meeting the requirements of the study