Measuring pre- and post-transplant minimal residual disease (MRD) “is a powerful predictor for survival” in pediatric acute lymphoblastic leukemia (ALL), according to a multi-center study of 648 patients.
A Cox regression analysis showed that pre-transplant MRD and remission status both significantly influenced survival. Age, sex, relapse site, cytogenetics, donor type, and stem cell source did not influence outcome.
Patients were treated in Europe, North America and Australia, and transplanted between 1999 and 2016. MRD was assessed prior to allogeneic hematopoietic cell transplantation (HCT) and at intervals starting post-HCT days +30, and beyond +365 days.
Patients were placed in 3 groups for analysis according to MRD level: 1) MRD negative (no detectable MRD); 2) MRD low positive (MRD <10-4); and 3) MRD high positive (MRD ≥10-4).
MRD high positive, low positive and negative patients experienced 4-year event-free survival of 37%, 67% and 62%, respectively (p<0.0005). Patients with a high pre-transplant MRD had a 2.47-fold increased hazard ratio for relapse and a 1.67-fold increased risk of transplant-related mortality (p<0.0005). At all pre- and post-transplant time points, MRD levels ≥10-4 were highly predictive of relapse.
The researchers concluded that in addition to being able to predict transplant survival, MRD measurement pre- and post-transplant could be used to guide post-transplant interventions in children with ALL.