Outcome of hematopoietic stem cell transplantation of children with very high risk acute lymphoblastic leukemia in first complete remission

Approximately 10% of children with ALL present at diagnosis with VHR for relapse if treated with chemotherapy alone. They may benefit from allogeneic HSCT in CR1. We have reviewed the outcome of this population in our institution. Forty-three patients (median age: 8.9 yr) with VHR ALL in CR1 underwent HSCT from October 1994 to April 2006. VHR features included Philadelphia chromosome (n = 17), induction failure (n = 9), hypodiploidy (n = 6), MLL gene rearrangement (n = 5), and others (n = 6). All patients received TBI (1200 cGy) with either CY and/or etoposide. Stem cell source was unrelated (n = 24) and related (n = 19). Incidence of grade III-IV acute GVHD and chronic extensive GVHD were 25% and 16%, respectively. Twelve patients relapsed (eight received related HSCT). Eleven patients died due to transplant-related mortality (eight received unrelated HSCT). For a median follow up of 39 months (range 11-110), the event free survival and OS were 0.49 (95% CI: 0.31-0.67) and 0.53 (CI: 0.44-0.71), respectively. Outcomes of children with VHR ALL receiving HSCT in CR1 remain unsatisfactory. Relapse, mainly after related HSCT, and TRM, mainly after unrelated HSCT, continue to be major problems.