OBJECTIVES: I. Determine the efficacy and toxicity of intensified systemic treatment with delayed central nervous system (CNS) irradiation in children with acute lymphoblastic leukemia and isolated CNS disease. II. Determine the efficacy of systemic thiotepa in reducing or clearing blasts in the cerebrospinal fluid of these patients. III. Evaluate the toxicity of single dose thiotepa followed by dexamethasone, vincristine, daunorubicin, and triple intrathecal therapy in these patients. IV. Determine the response rate of intrathecal sustained release cytarabine (DTC101) in patients with first bone marrow remission with first isolated CNS relapse. V. Assess the safety and toxicity of DTC101 in these patients.

OUTLINE: Patients with significant neurologic symptoms (e.g., seizures, cranial nerve palsy, paresis, mental status changes) are entered directly on the Induction regimen and do not receive the Therapeutic Window. The following acronyms are used: ARA-C Cytarabine, NSC-63878 ASP Asparaginase, NSC-109229 (E. coli) or 106977 (Erwinia) CF Leucovorin calcium, NSC-3590 CTX Cyclophosphamide, NSC-26271 DM Dexamethasone, NSC-34521 DNR Daunorubicin, NSC-82151 DTC101 Sustained release cytarabine G-CSF Granulocyte Colony-Stimulating Factor (Amgen), NSC-614629 HC Hydrocortisone, NSC-10483 Mesna Mercaptoethane sulfonate, NSC-113891 MP Mercaptopurine, NSC-755 MTX Methotrexate, NSC-740 TIT Triple Intrathecal Therapy, IT MTX/IT HC/IT ARA-C TMP-SMX Trimethoprim-sulfamethoxazole TSPA Thiotepa, NSC-6396 VCR Vincristine, NSC-67574 VP-16 Etoposide, NSC-141540 THERAPEUTIC WINDOW: Single Agent Chemotherapy. TSPA or DTC101. ** Thiotepa window closed as of 7/6/98 ** ** DTC101 window opened 11/15/99 ** INDUCTION: 3-Drug Combination Chemotherapy plus Triple Intrathecal Therapy. DM/DNR/VCR; plus TIT. CONSOLIDATION: 2-Drug Combination Chemotherapy plus Triple Intrathecal Therapy. ARA-C/ASP; plus TIT. INTENSIFICATION I: 4-Drug Combination Chemotherapy with Leucovorin Rescue plus Triple Intrathecal Therapy. CTX/MP/MTX/VP-16; with CF; plus TIT. RE-INDUCTION: 3-Drug Combination Chemotherapy plus Triple Intrathecal Therapy. DM/DNR/VCR; plus TIT. INTENSIFICATION II: 6-Drug Combination Chemotherapy with Leucovorin Rescue plus Triple Intrathecal Therapy. ARA-C/ASP/CTX/MP/MTX/VP-16; with CF; plus TIT. CHEMORADIOTHERAPY: Radiotherapy plus 3-Drug Combination Chemotherapy. Craniospinal irradiation using x-rays with energies of 4-6 MV (electrons acceptable for spinal cord irradiation); plus ASP/DM/VCR. MAINTENANCE: 2-Drug Combination Chemotherapy Alternating with 2-Drug Combination Chemotherapy. MP/MTX; alternating with CTX/VCR.

PROJECTED ACCRUAL: 156 patients will be accrued over approximately 4 years. Up to 40 evaluable patients will be studied in the Therapeutic Window (20 patients with thiotepa; 20 patients with DTC101), after which that regimen will close (thiotepa window closed 7/6/98; sustained release cytarabine window opened 11/15/99); if 5 of the first 10 patients experience > 50% increase in blasts 1 week after treatment, or if 3 patients exhibit 100% blast clearing, the Therapeutic Window will close early.

DISEASE CHARACTERISTICS: Acute lymphoblastic leukemia in first bone marrow remission (M1) with first isolated initial CNS relapse, i.e.: More than 5 WBC/microliter in cerebrospinal fluid (CSF) with blasts on cytospin OR Immunophenotypic proof (encouraged) of relapse in CSF, i.e.: Identifiable blasts and presence on 2 CSF samples 3 weeks apart of: If B-cell: terminal deoxynucleotidyl transferase (TdT) or CD-10 If T-cell: TdT alone or with CD-7

PATIENT CHARACTERISTICS: Age: Over 6 months and under 21 years at relapse Patients receiving sustained release cytarabine: Performance status: Older than 10 years: Karnofsky greater than 50% Less than 10 years: Lansky greater than 50% Hematopoietic: Platelet count greater than 40,000/mm3 Hepatic: Bilirubin less than 2.0 mg/dL SGPT less than 5 times normal Renal: Creatinine less than 1.5 times normal for age Metabolic: Normal metabolic parameters (serum electrolytes, calcium, and phosphorus) Other: No clinical evidence of obstructive hydrocephalus, compartmentalization of the CSF flow, ventriculoperitoneal or ventriculoatrial shunt

PRIOR CONCURRENT THERAPY: Prior cumulative anthracycline dose less than 375 mg/sqm Patients receiving sustained release cytarabine: At least 7 days since prior investigational drug At least 3 weeks since prior CNS directed therapy (6 weeks is prior nitrosourea) At least 1 week since intrathecal chemotherapy At least 8 weeks since prior craniospinal radiotherapy