Total Lymphoid Irradiation as Conditioning for Pediatric Haploidentical Hematopoietic Stem Cell Transplantation

Total Lymphoid Irradiation as Conditioning for Pediatric Haploidentical Hematopoietic Stem Cell Transplantation

In this comparative study, the investigators aim to compare prospective pediatric patients who receive total lymphoid irradiation (TLI) using tomotherapy with age- and disease-matched controls who receive conventional total body irradiation (TBI) as part of conditioning for haploidentical hematopoietic stem cell transplantation (HSCT) for both malignant and non-malignant diseases. The investigators shall evaluate graft failure-free, graft-versus-host disease (GVHD)-free survival, overall survival, frequency of rejection, GVHD, relapse of malignancy, adverse effects and post-transplant immunoreconstitution.

Radiotherapy at a dose of 6Gy divided into 3 equal fractions (2Gy per fraction) to all lymphoid organs (TLI) over 2 days using tomotherapy will be given to participants as part of the conditioning treatment before haploidentical hematopoietic stem cell transplantation (HSCT). Retrospective patients who are age- and disease-matched with the recruited patients and had received radiotherapy to the whole body (TBI) with or without lung shielding at a total dose of 2-12 Gy delivered as 1-6 equal fractions by conventional opposed fields radiotherapy as part of conditioning will be compared for the outcomes.

Inclusion Criteria:

• Aged 0-18 years who requires allogeneic HSCT, has no human leukocyte antigen (HLA)-matched sibling donor but has an HLA-haploidentical donor.
• Adequate organ function to tolerate the conditioning chemotherapy and radiotherapy
• Karnofsky or Lansky performance status score ≥50

Exclusion Criteria:

• Pregnant or lactating woman
• HIV infection
• Patients for whom alternative treatment is deemed more appropriate by treating physician
• Patients who are unlikely to benefit from haploidentical hematopoietic stem cell transplantation, e.g., terminal malignancy with multiorgan failure