[Long-term results of multicenter study based on childhood acute lymphoblastic leukemia 2005 protocol]

Objective: To evaluate the long-term efficacy and prognostic factors of childhood acute lymphoblastic leukemia (ALL) enrolled in Shanghai Children's Medical Center-Acute Lymphoblastic Leukemia-2005(SCMC-ALL-2005) multicenter study. Methods: Between May 2005 and December 2014, 1 497 newly diagnosed ALL patients were enrolled and treated in 5 hospitals of SCMC-ALL-2005 study group, using risk-stratified SCMC-ALL-2005 protocol. Risk group classification and treatment intensity were based on clinical features, genetic abnormalities, early response to treatment and levels of minimal residual disease (MRD). Kaplan-Meier method was used to generate overall survival (OS) and event-free survival(EFS) curves. Cox proportional hazards models were used for multivariate analyses. Results: The patients were followed up to December 31, 2016, the median follow-up time was 69 months (24-141 months). The 5-year and 10-year OS rates were (80.0±1.0)% and (76.0±2.0)%. The 5-year and 10-year EFS rates were (69.0±1.0)% and (66.0±2.0)%. The 5-year and 10-year relapse rates were (23.0±1.0)% and (25.0±2.0)%. The 5-year OS and EFS for low risk (LR), intermediate risk (IR) and high risk (HR) were (91.1±1.4)% and (83.3±1.8)%, (79.2±1.5)% and (68.9±1.7)%, (52.9±4.4)% and (30.0±3.8)%, respectively. MRD negative status (<0.01%) on day 55 was seen in 792 patients (82.8%) and positive MRD on day 55 was associated with poor prognosis (OR=1.9, 95%CI: 1.3-2.7, P=0.001). Twenty-four HR patients received allogeneic hematopoietic stem cell transplantation and 17(70.8%) of them were alive and in remission. A total of 164 severe adverse events occurred, 46 of them died, treatment-related mortality was 3.1%. Conclusions: In this large sample research, the overall outcome for multi-center SCMC-ALL-2005 study was favorable. This helps to promote the standardized treatment of childhood ALL to the whole country. MRD results on day 55 of induction therapy have important prognostic and therapeutic implications.