Increased Use of Allogeneic Transplant in CR2 Improves the Outcome for Children with Acute Myeloid Leukaemia

Improvements in Outcome for Paediatric de novo Acute Myeloid Leukaemia Aditi Vedi1,2, Richard Mitchell1, Cecelia Oswald1, Glenn Marshall1,2, Toby Trahair1, David S Ziegler1,2 1Kids Cancer Centre, Sydney ChildrenÕs Hospital, Randwick, NSW, Australia, 2School of Women and Children's Health, University of New South Wales, Randwick, NSW, Australia ABSTRACT The treatment for paediatric acute myeloid leukaemia (AML) has not changed significantly over the past 3 decades, yet outcomes have improved with cure rates increasing from 30% to over 50% of all newly diagnosed children over this period. This improvement in survival has been attributed to both treatment intensification and improved supportive care over the decades, although the precise impact of each remains unknown. Our group has retrospectively analysed a unique cohort of patients with de novo AML diagnosed in childhood (n=276), all treated with the same chemotherapy protocol over a 25-year period from 1986-2012. The contemporary cohort (2000-12), compared to historical cohorts (1986-99) had significantly improved overall survival (OS, 75% vs. 50%, p = 0.01), lower disease related mortality (38% vs. 19%, p = 0.02) and were significantly more likely to receive allogeneic transplant after relapse (SCT, 73% vs. 12%, p <0.0001). Allogeneic transplant post relapse was associated with a significantly improved survival across the entire cohort (OS 50% for allogeneic SCT vs. 12% for autologous or none, p<0.0001). There was no significant difference between the contemporary and historical cohorts in treatment related mortality (13% vs. 7%, p = 0.42) or relapse rates after induction (50% in older cohort vs. 40% in recent era, p=0.25), suggesting consistency of induction treatment efficacy and toxicity across the two periods. This data suggests improved survival in paediatric AML in the modern era has predominantly resulted from increased use of allogeneic SCT after relapse rather than from improved supportive care and is independent of chemotherapy intensification.