Intermediate dose of imatinib in combination with chemotherapy followed by allogeneic stem cell transplantation improves early outcome in paediatric Philadelphia chromosome‐positive acute lymphoblastic leukaemia (ALL): results of the Spanish Cooperative Group SHOP studies ALL‐94, ALL‐99 and ALL‐2005

Philadelphia-chromosome acute lymphoblastic leukaemia (Ph+ ALL) is a subgroup of ALL with very high risk of treatment failure. We report here the results of the Sociedad Española de Hematología y Oncología Pediátricas (SEHOP/SHOP) in paediatric Ph+ ALL treated with intermediate-dose imatinib concurrent with intensive chemotherapy. The toxicities and outcome of these patients were compared with historical controls not receiving imatinib. Patients with Ph+ ALL aged 1-18years were enrolled in three consecutive ALL/SHOP trials (SHOP-94/SHOP-99/SHOP-2005). In the SHOP-2005 trial, imatinib (260mg/m(2) per day) was given on day-15 of induction. Allogeneic haematopoietic stem-cell transplantation (HSCT) from a matched related or unrelated donor was scheduled in first complete remission (CR1). Forty-three patients were evaluable (22 boys, median age 6·8years, range, 1·2-15). Sixteen received imatinib whereas 27 received similar chemotherapy without imatinib. Seventeen of 27 and 15 of 16 patients in the non-imatinib and imatinib cohort, respectively, underwent HSCT in CR1. With a median follow-up of 109 and 39months for the non-imatinib and imatinib cohorts, the 3-year event-free survival (EFS) was 29·6% and 78·7%, respectively (P=0·01). These results show that, compared to historical controls, intermediate dose of imatinib given concomitantly with chemotherapy and followed by allogeneic HSCT markedly improved early EFS in paediatric Ph+ ALL.