Comparison of total body irradiation versus oral busulfan in the conditioning of allogenic hematopoietic stem cell transplantation in adult patients with acute lymphoblastic leukemia

Abstract

Background
Allogenic hematopoietic stem cell transplantation (allo-HSCT) with a myelo-ablative conditioning regimen is considered the most potent postremission anti-leukemic therapy in adult acute lymphoblastic leukemia (ALL)., it remains controversial whether Busulfan (Bu) -based versus total body irradiation (TBI) based regimens have comparable outcomes in patients with ALL undergoing allo-HSCT. Our retrospective study was conducted on 84 adult Egyptian patients with ALL, who were candidates for allogenic HSCT between 2005 and 2014 at the BMT Unit at Nasser Institute Hospital for Research and Treatment, Ministry of Health and Population. We compared TBI/CY versus BU/CY as a conditioning regimen before allo-HSCT, as regards; transplant outcomes [disease free survival (DFS) and overall survival (OS)], regimen-related toxicities and transplant-related mortality. It was TBI/CY group (n=62) and BU/CY group (n=22), with the same inclusion and exclusion criteria.


Results
The OS among patients of TBI/CY group (56.5%) with a median of 47.7 months; while, there was (40.9%) in BU/CY group, with median of 11.5 months, but with no statistically significant value (P>0.05). There was a statistically significant higher patients relapsed in BU/CY group was eight (36.4%) patients compared with TBI/CY group was nine (14.5%) patients, with P value (P=0.028). There was a statistically significant difference among the two survival curves of DFS (P value = 0.002). The DFS was (85.5%) in the TBI/CY group with a mean of 19.75 months, while the DFS of BU/CY was (43.7%) with a mean of 13.9 months. Transplant-related mortality was 71.4% and 60.0% in TBI/CY and BU/CY, respectively, calculated as a number of deaths in the first 100 days after transplant about the total number of deaths with no statistical (P>0.05) significance. There was a statistically significant higher abnormal maximum Bilirubun level in first 100 days in BU/CY group recorded in nine (86.4%) patients compared with TBI/CY group 39 (62.9%) patients, with P value (P 0.041). Finally, the incidence of HC was statistically significantly higher in BU/CY group [five (22.7%) patients] than in TBI/CY group [four (6.5%) patients] with P value (0.034).


Conclusion
TBI/CY appears to be superior to BU/CY as a conditioning regimen for adult patients with ALL who are candidates for allogenic HSCT, as regards survival rates, OS, and shows higher DFS with lower relapse rates.