MRD detection just before transplant

Remission status at the time of transplant has long been known to be an important predictor of outcome, with patients not in CR at HSCT having very poor survival rates.[100] Several studies have also demonstrated that the level of MRD at the time of transplant is a key risk factor in children with ALL in CR undergoing allogeneic HSCT.[27,101-109][Level of evidence C1]; [21,29,92,110] Survival rates of patients who are MRD positive pretransplant have been reported between 20% and 47%, compared with 60% to 88% in patients who are MRD negative.

When patients received two to three cycles of chemotherapy in an attempt to achieve an MRD-negative remission, the benefit of further intensive therapy for achieving MRD negativity must be weighed against the potential for significant toxicity. In addition, there is not clear evidence showing that MRD positivity in a patient who has received multiple cycles of therapy is a biological disease marker for poor outcome that cannot be modified, or whether further intervention bringing such patients into an MRD negative remission will overcome this risk factor and improve survival.