Allogeneic hematopoietic cell transplantation outcomes for children with B-precursor acute lymphoblastic leukemia and early or late BM relapse.

Large registry studies have shown superior disease-free survival (DFS) with matched sibling donor (MSD) allogeneic hematopoietic cell transplantation (allo-HCT) over chemotherapy alone for patients with B-precursor acute lymphoblastic leukemia (ALL) and a late BM relapse. As most of these patients will not have an MSD, the decision to pursue an unrelated allo-HCT in second remission (CR2) or await a future relapse and perform HCT in third remission (CR3) continues to be debated. Between 1990 and 2006, 41 children with relapsed B-precursor ALL received a myeloablative allo-HCT at the University of Minnesota. Graft sources consisted of matched related donor (n=11), matched unrelated donor (n=9), and unrelated umbilical cord blood (n=21). Before allo-HCT, 15 patients had an early relapse (<36 months from diagnosis) and 26 had an initial late relapse (36 months from diagnosis). In all, 30 patients (73%) were in CR2 and 11 were in CR3 (27%) at time of allo-HCT. Five year OS/DFS were similar for patients with an early or late marrow relapse, but there was inferior DFS among late-relapse patients transplanted in CR3 compared with CR2 (30% vs 75%, P=0.04). These results suggest that allo-HCT should be pursued in children after a first marrow relapse, rather than waiting for subsequent recurrence.