Outcome of the Modified St. Jude Total XV Protocol in Turkish Children with Newly Diagnosed Acute Lymphoblastic Leukemia: A Single-Center Retrospective Analysis

Objective: The prognostic factors and outcomes of Turkish children with newly diagnosed acute lymphoblastic leukemia (ALL), treated with the Modified St. Jude Total XV Protocol, which was adjusted by adding high-dose methylprednisolone (HDMP) before induction in the original protocol, were assessed in this study.

Materials and methods: The Modified St. Jude Total XV Protocol was administered to 183 newly diagnosed ALL patients, aged 1-18 years, between 1 January 2008 and 30 January 2016. HDMP was applied at doses of either 10 mg/kg/day (Group A) or 20 mg/kg/day (Group B) for 7 days before induction and then tapered over the next 7 days to 5 or 10 mg/kg/day, and continued at 2 mg/kg/day for 2 weeks during the induction phase. Absolute blast count (ABC) in peripheral blood and minimal residual disease (MRD) in bone marrow were assessed at the end of the initial 7-day HDMP treatment. MRD in the bone marrow was evaluated on day 15 and at the end of the induction period. The follow-up for these patients ended on 15 July 2019.

Results: The 5-year event-free (EFS) and overall survival (OS) rates for all patients were 85.6±2.6% and 89.2±2.3%, respectively. The rate of good response to steroids (defined as ABC in peripheral blood of less than 1000/mm3 on day 7) was 88% and 97% of children achieved complete remission after induction. The survival rate and infection frequency did not show statistically significant differences between Group A and B. EFS and OS correlated with initial leukocyte count, age of 10-18 years at diagnosis, CD20 positivity at diagnosis, and gram-negative bacterial infection during remission induction.

Conclusion: The remarkable response rates on days 7 and 15, along with the promising EFS and OS results in childhood ALL patients treated with the Modified St. Jude Total XV Protocol, highlight the early and substantial response effect of HDMP. At the onset of induction, short-term HDMP can be initiated, preferably at 10 mg/kg/day for the first 7 days, to minimize potential side effects.