This study investigates how well combination chemotherapy works in treating young patients with acute lymphoblastic leukemia (ALL), a type of cancer that affects the blood and bone marrow and is likely to return or spread. The purpose is to see if a specific treatment approach can improve disease-free survival in children with high-risk B-ALL compared to another treatment method.

Participants will receive different chemotherapy regimens to compare their effectiveness. Some will receive a combination including cyclophosphamide and etoposide, while others will follow a modified regimen with high-dose methotrexate. These treatments aim to find out which approach provides better outcomes for patients.

• Who can participate: Eligible participants are those aged 1 to 30 years with newly diagnosed B lymphoblastic leukemia. Children with Down syndrome are also eligible. Specific white blood cell count criteria apply: for children under 10, WBC must be less than 50,000/μL; for those 10 and older, WBC must be less than 100,000/μL.
• Study details: Participants will be randomly assigned to receive one of two chemotherapy regimens. One group will receive a combination of cyclophosphamide and etoposide, while the other will follow a modified regimen.