OBJECTIVETo reduce the risk of infection during the induction therapy while to ensure remission rates, and to evaluate the protocol ALL-2005.

METHODSThe minimal residual disease (MRD) was detected by flow cytometry on day 35 and 55 of induction therapy. The efficacy of induction and the clinic grouping were evaluated by MRD level. From May 1, 2005 to April 30, 2007, 158 children with newly diagnosed ALL were enrolled in this study. According to clinic grouping criteria of ALL-2005, patients were stratified into 3 groups: low-risk( LR), intermediate-risk (MR) and high-risk (HR). The remission rates, therapy related complication during induction, and the relationship between MRD level on day 35 and 55 of induction and prognosis were analyzed. The endpoints are disease-free survival (DFS), relapse and death of any cause. Patients lost to follow-up were censored at the time of their withdrawal.

RESULTSOf the 158 patients, 59 were LR, 93 MR and 6 HR. The CR rate on day 35 was 98.1%. There were detectable MRD in 139 (88.0%) patients. In 94 patients (68.6%) MRDs were < or = 0.01% on day 35 being 73.1% (49/67) for LR and 63.4% (45/71) for MR (P = 0.219). During induction therapy, 43 patients (27.2%) developed infection and among them 1.3% (2/158) suffered serious infection and 0.6% (1/158) died of complication. Four patients (2.5%) in CR were lost follow-up, 17 patients (10.8%) relapsed, including 4 patients (4.3%) with MRD < or = 0.01% and 10 (23.3%) >0.01% on day 35 (P = 0.003). One died of severe malnutrition and infection in CR. With a median follow-up of 20 (12-35) months, the estimated 30 month DFS for whole group was (81.6 +/- 4.5)% including (94.1 +/- 3.3)% for LR, (82.8 +/- 4.4)% for MR, and (91.0 +/- 5.4)% for MRD < or = 0.01%, (67.1 +/- 9.5)% for MRD >0.01% on day 35 and (89.1 +/- 5.3)% for MRD < or = 0.01% and (46.9 +/- 15.6)% for MRD >0.01% on day 55.

CONCLUSIONThe risk of infection and therapy related death during induction with protocol ALL-2005 are lower, while the remission rate and quality of the induction are better. Longer follow-up is needed to estimate the long-term result.