Hematopoietic Stem Cell Transplantation for Childhood Acute Lymphoblastic Leukemia and the Role of MRD: A Single Centre Experience from India.

Hematopoietic stem cell transplantation (HSCT) is an effective curative option for children with relapsed and high risk acute lymphoblastic leukemia (ALL). The effect of minimal residual disease (MRD) prior to transplantation has a significant impact on the overall outcome. We performed a retrospective analysis of children with ALL who underwent HSCT at our centre from 2002 to 2016. From 2002 to 2008 disease status was determined by morphology and karyotyping and from 2008 onwards by flow cytometry. A total of 46 children were transplanted for ALL at our centre. Of the 19 children who were MRD positive prior to HSCT 5 had a relapse after the transplant. Among the remaining 26 MRD negative children, only one child relapsed post HSCT. The EFS was 66.6% in the MRD negative group and 63.1% in positive group with no significant survival advantage of the first group over the second, ( 0.37). GVHD was the major cause of mortality overall at 56.7% as well as in the MRD negative group at 77.7%(7/9). On the other hand, relapse was the major mortality factor at 71.4%(5/7) in the MRD positive group. Molecular remission prior to HSCT shows a trend towards lesser chance of relapse. We should strive to achieve MRD negative status prior to transplant to improve EFS. However, GVHD is also emerging as a crucial factor and its impact on survival outcome in children undergoing HSCT for ALL needs to be followed up.