Effective VCR/DEX pulse maintenance therapy in the KYCCSG ALL-02 protocol for pediatric acute lymphoblastic leukemia

In a previous study of childhood acute lymphoblastic leukemia (ALL) by the Kyushu-Yamaguchi Children's Cancer Study Group, ALL-96, we achieved a 72.1 % 5-year event-free survival (EFS) and an 84.8 % 5-year overall survival (OS). In a subsequent study, ALL-02, we adopted a vincristine dexamethasone (VCR/DEX) pulse regimen as maintenance therapy in the context of the ALL-96 study using the same risk classification and treatment schedule. A total of 156 pediatric cases of ALL were treated with ALL-02. All of the patients were classified as standard-risk or high-risk. Risk stratification was based on white cell counts, immunophenotype, the presence of central nervous system (CNS) disease at diagnosis, organomegaly, and early treatment response (day 14 bone marrow status). The 7-year EFS and OS rates were 77.7 % (95 % CI 70.6-84.8 %) and 89.5 % (95 % CI 84.6-94.4 %), respectively. CNS 3 status [hazard ratio (HR) = 5.0, p = 0.009] and high white blood cell count at diagnosis (HR = 2.6, p = 0.047) were risk factors for poor EFS in multivariate analysis. Our strategies to categorize patients into two risk groups, and to treat with a VCR/DEX pulse were feasible and reasonably effective treatments for pediatric ALL.