A Clinical Study on the Efficacy and Safety of Ivarmacitinib in Preventing aGVHD After HLA-matched Transplantation

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