A low-toxicity myeloablative conditioning regimen is safe and effective in treating high-risk leukemias, particularly myeloid disease, according to a study recently published in the journal Pediatric Blood & Cancer.
A low-toxicity myeloablative conditioning regimen is safe and effective in treating high-risk leukemias, particularly myeloid disease, according to a study recently published in the journal Pediatric Blood & Cancer.
Conventional myeloablative conditioning is effective at reducing the risk of a relapse in pediatric hematologic malignancy patients who are undergoing allogeneic hematopoietic stem cell transplant (HCT).
But the conventional regimen using busulfan and cyclophosphamide causes significant toxicities and is associated with significant potential morbidities.
Modified regimens using busulfan and fludarabine are associated with decreased toxicities, but it is unknown whether the addition of a low dose of total body irradiation will enhance the anti-leukemia effects in pediatric patient.
To answer this question, the study examined a reduced-toxicity myeloablative conditioning regimen using dose-adjusted busulfan, fludarabine and antithymocyte globulin, plus 400 centigrays (cGy) of total body irradiation.
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The study evaluated 40 patients under age 21 undergoing HCT for high-risk leukemias. Busulfan pharmacokinetics targeted 4,000 micromoles*minute per day (μmol*min/day) in the first 30 patients. In an effort to further decrease relapse risk, the dosage was increased to 5,000 μmol*min/day in the subsequent 10 patients.
Overall survival at two and five years post-HCT was 67% and 51%, respectively, the authors wrote in “Reduced-toxicity Conditioning Regimen with Busulfan, Fludarabine, rATG, and 400 cGy TBI in Pediatric Patients Undergoing Hematopoietic Stem Cell Transplant for High-Risk Hematologic Malignancies.”
The study was performed at the Ann & Robert H. Lurie Children’s Hospital of Chicago, Illinois. The authors of the study included William T. Tse, M.D., Ph.D., currently a pediatric hematologist/oncologist with Norton Children’s Cancer Institute, affiliated with the UofL School of Medicine. Dr. Tse is medical director of the Hanna Catherine Evans Bone Marrow and Stem Cell Transplant Program at Norton Children’s Cancer Institute.
The low-toxicity myeloablative conditioning regimen showed improved survival in myeloid disease patients who received HCT using bone marrow as stem cell source and achieved a busulfan area-under-the-curve greater than 4,000 μmol*min/day. Two-year survival without a relapse approached 80%, the authors wrote.
“This conditioning regimen is safe and effective in patients with high-risk leukemias, particularly myeloid disease,” the authors concluded. “Larger studies are needed to compare its safety and efficacy to other myeloablative regimens in this population.”
