Combination of Haploidentical Hematopoietic with Low-Dose TBI and Cord Blood Transplantation for Hematologic Malignancies

Objective: To evaluate the efficacy and safety of the combination of haploidentical hematopoietic with low-doseTotal body irradiation（TBI）and cord blood transplantation for hematologic malignancies.

Methods: This study was conducted as a retrospective review of medical records of 5 patients with hematologic malignancies who received a combination of haploidentical hematopoietic with low-dose TBI and cord blood transplantation at Affiliated HangZhou first people's hospital of Zhejiang University school of medicine, from March to June 2021.

Results: 5 patients were included for the analysis. There were 1 acute myeloid leukemia (AML),2 acute lymphoblastic leukemia (ALL) and 2 Non-Hodgkin's Lymphoma(NHL). The minimal residual disease (MRD) of the two patients with ALL was positive before allo-HCT.Median age of patients at the time of allo-HCT was 30 years (range 21-63 years). All patients received low-dose TBI(4-6GY) +antithymocyte globulin（ATG）based conditioning.Cord blood units were selected based on the results of HLA typing and cell doses evaluated before freezing. Units with at least 4/6 matched HLA loci became the candidates. The median values of absolute total nucleated cell counts were 139.0 (80.8-240.0) × 10 ⁷ / kg in The haploidentical grafts and 2.25 (1.32-3.10)× 10 ⁷ / kg in the cord blood units,respectively. The median doses of CD34+ cells infused were 28.6 (22.0-51.1) × 10 ⁵ / kg in the haploidentical grafts and 1.5 (1.0-3.5)×10 ⁵/kg in the cord blood units, respectively.All patients attained complete engraftment,of which 3 were haploidentical engraftment and 2 were mixed hematopoietic chimerism that included haploidentical and cord blood engraftment.The median time to neutrophil engraftment was 12 (10-22) days and 13 (11-22) days for platelets. All patients were in complete remission with MRD-negetive during a median follow-up of 83 (34-136) days.No patients developed grade II-IV acute graft versus host desease.

Conclusion:The results suggested that the combination of haploidentical hematopoietic with low-dose TBI and cord blood transplantation may potentially improve the outcome of HSCT. It offers a transplant alternative for patients with hematologic malignancies who lack matching donors.