Population PK-guided ATG Dosing for Haploidentical Hematopoietic Stem Cell Transplantation

To evaluate the safety and efficacy of a population pharmacokinetics (PK)-guided targeted ATG dosing strategy in haploidentical stem cell transplantation and to observe the GVHD-free, relapse-free survival (GRFS) in the cohort receiving this strategy.

Inclusion Criteria: * Patients with indications for allogeneic hematopoietic stem cell transplantation, with malignant hematologic diseases in CR1 or CR2 before transplantation. * Have an HLA-matched sibling, unrelated, or haploidentical donor. * Age ≥ 14 years and ≤ 75 years. * Liver function: ALT and AST ≤ 2.5 × upper limit of normal, bilirubin ≤ 2 × upper limit of normal. * Renal function: creatinine ≤ upper limit of normal. * No uncontrolled infection or severe mental or psychological disorders. * ECOG performance status score of 0-2. * Signed informed consent. Exclusion Criteria: * No HLA-matched donor. * Malignant hematologic disease in CR3 or higher disease stage, or refractory/relapsed status. * Patient age \< 14 years or \> 75 years. * Pregnancy of either the donor or the recipient. * Presence of mental illness or other conditions that preclude compliance with the protocol.