The purpose of this study is increase the efficacy of consolidation (C1) after an intensification phase with high dose of methotrexate, applying analysis of minimal residual disease

REMISION INDUCTION

Systemic chemotherapy:

Prednisolone (PDN):

• 60 mg/m2 day, i.v. or p.o., days 1 to 27
• 30 mg/m2 day, i.v. or p.o., days 28 to 35

Vincristine (VCR): 1,5 mg/m2 i.v., days 8, 15, 22 and 28. Daunorubicin (DNR): 30 mg/m2, i.v., days 8 and 15. L-asparaginase (L-ASA): 10.000 UI/m2, i.m. or i.v., days 9 to 11, 16 to 18 and 23 to 25.

Cyclophosphamide (CFM): 1000 mg/m2, i.v., day 22.

Intracranial chemotherapy

Methotrexate (MTX), cytosine (ARA-C) and hydrocortisone, days 1 and 22

CONSOLIDATION TREATMENT (WEEKS 6 TO 14)with INTENSIFICACIÓN (C-1)

• Mercaptopurine (MP) 50 mg/m2, p.o., days 1-7, 28-35 and 56-63
• MTX: 3g/m2, i.v., in 24 hours, days 1, 28 and 56.
• VP-16: 150 mg/m2 i.v., days 14-15 and 42-43
• ARA-C: 1000 mg/m2 i.v., in 3 hours, days 14-15 and 42-43
• Intrathecal treatment, days 1, 28 and 56.

REINDUCTION-CONSOLIDATION TREATMENT (R-C) (WEEKS 15 TO 23)

Dexamethasone (DXM):

• 6 mg/m2 day, p.o., days 1-21
• 3 mg/m2 day, p.o. or i.v., days 22-28 VCR: 1,5 mg/m2, i.v., days 1, 8 and 15 DNR: 30 mg/m2, i.v., days 1 and 8 L-ASA: 10.000 UI/m2 i.m. or i.v., days 8 and 9, 15 and 16, 22 and 23. CFM 1000 mg/m2 day, i.v., day 22 Mercaptopurine (MP) 50 mg/m2, p.o., days 35-42 MTX: 3g/m2, i.v., in 24 hours, day 35. VP-16: 150 mg/m2 i.v., days 49-50 ARA-C: 1.000 mg/m2 i.v., in 3 hours, days 49-50 Intrathecal treatment days 1 and 35.

MAINTENANCE TREATMENT (M-1)

Continuous treatment

• MP 50 mg/m2/day, p.o.
• MTX 20 mg/m2/week, i.m.

Reinductions

• VCR: 1,5 mg/m2 i.v., day 1.
• PDN: 30 mg/m2/day, i.v. or p.o., days 1 to 7
• L-ASA: 20.000 UI/m2, i.m. or i.v., day 1.
• Intrathecal treatment day 1 Five cycles, weeks 24, 30, 36, 42 and 48. During the week of administration cycle, continuous chemotherapy should be suspended.

Intrathecal treatment: At the start of any reinduction cycle

MAINTENANCE TREATMENT (M-2) (WEEKS 55-108)

• MP 50 mg/m2/day, p.o.
• MTX 20 mg/m2/week, i.m.
• Intrathecal treatment, weeks 54 and 108

At the end of treatment should be done the study of MRD (flux cytometry)

Inclusion Criteria:

• Diagnoses of low risk acute lymphoblastic leukemia in children no treated previously

Exclusion Criteria:

• Mature B-ALL (FABL3) or with cytogenetic ALL "Burkitt-like" alterations (t[8;14], t[2;8], t[8;22])
• Mixed forms of ALL
• Acute Leukemia no differentiate
• Patients with coronary disorders, valvular or hypertensive cardiopathy
• Patients with chronic liver disorders
• Chronic pulmonary disorders
• Renal insufficiency
• Neurologic disfunctions
• ECOG 3 and 4
• No signed consent form