Abatacept s.c. for aGVHD Prevention in Haplo-HCT

Inclusion Criteria: 1. Age≧18 years 2. ECOG score 0-2 / Karnofsky score≧80 3. haplo-HCT is proposed 4. Conditioning with motified Bu/Cy+ATG regimen 5. Having the following hematologic malignancies with transplant indications: 1. Acute leukemia 2. Myelodysplastic syndrome 3. Aggressive lymphoma 6. Expected survival ≥ 3 months 7. Written informed Consent can be acquired 8. Agree to use effective contraception Exclusion Criteria: 1. With a history of allo-HCT previously 2. Allergic/intolerant to Abatacept 3. Contraindications to the use of Abatacept 4. HIV infection, or active HBV infection or HCV infection 5. Uncontrolled active infection 6. Vital organ function intolerated to transplantation 7. Other malignancies except for the following diseases: malignant tumors that have been cured for at least 3 years without active lesions; adequete treated non-melanoma skin cancer, malignant amygdala, and carcinoma in situ without active lesions 8. Evidence of complications or medical conditions that may interfere with research or put the subjects at serious risk, including but not limited to severe cardiovascular disease (e.g. New York Heart Association grade III or IV heart disease, myocardial infarction in the past 6 months, unstable arrhythmia or unstable angina) and/or severe lung disease (e.g. history of severe obstructive lung disease and symptomatic bronchospasm) 9. Pregnant and lactational women 10. Any life-threatening disease, medical condition, or organ dysfunction unfit for participants, or may interfere with the absorption or metabolism of Abatacept