Clinical Study of rATG Individualized Administration in Haploidentical Hematopoietic Stem Cell Transplantation

Clinical Study of rATG Individualized Administration for Prevention of GVHD and Maintenance of GVL in Haploidentical Hematopoietic Stem Cell Transplantation.

The purpose of this prospective, open-label, pairing design, single-center study is to evaluate the effect of individualized rATG dosing vs traditional weight-based rATG dosing regimen（10mg/kg）for patients with acute leukemia undergoing a myeloablative conditioning regimen and haploidentical hematopoietic stem cell transplantation (haplo-HSCT).

Allogeneic hematopoietic stem-cell transplantation (HSCT) is a potentially curative treatment option for acute leukemia. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) has become the main choice for acute leukemia in China. Major difficulties of the procedure include graft-versus-host disease (GVHD), graft failure, and relapse. As an important role of haplo-HSCT, Rabbit anti-thymocyte globulin (rATG), a polyclonal rabbit-derived antibody that depletes lymphocytes, including T cells, was introduced to prevent GVHD and transplant rejection.

The recommended dose of rATG in haplo-HSCT is 10 mg/kg. However, while the traditional weight-based rATG dosing regimen (10mg/kg) reduces the incidence of GVHD, it increases the risk of delayed immune reconstitution, viral reactivation, and relapse in patients. Our previous retrospective study showed that active ATG exposure (area under the curve, AUC)) post-transplantation is associated with immune reconstitution, GVHD, relapse, survival, and viral reactivation in HSCT of acute leukemia patients. Identifying the optimal dose of ATG to achieve the optimal exposure range of active ATG is a pressing clinical issue.

The pharmacokinetics of ATG varies significantly in both pediatric and adult populations, especially the active ATG levels, and clarifying the relationship between the pharmacokinetics of ATG and the prognosis of patient outcomes can help in precise treatment. By constructing a population pharmacokinetic model of ATG, we can provide an individualized optimal dose of ATG based on factors prior to transplantation. ATG individualized administration may improve the survival and quality of life of patients undergoing haplo-HSCT. A prospective pairing design trial is required to evaluate the effect of individualized rATG dosing vs traditional weight-based rATG dosing regimen (10mg/kg) for patients with acute leukemia undergoing haplo-HSCT.

Inclusion Criteria:

1. All patients were diagnosed with acute leukemia.
2. All patients should have the indication of Haploidentical hematopoietic stem cell transplant and receive the myeloablative conditioning regimen.
3. All patients should sign an informed consent document indicating that they understand the purpose of and procedures required for the study and be willing to participate in the study.

Exclusion Criteria:

Patients with any conditions not suitable for the trial (investigators' decision).