• Toxicity rate (Phase I) [ Designated as safety issue: Yes ]
  
• Overall survival rate at 2 years (Phase ll) [ Designated as safety issue: No ]
  

• Pre-irradiation chemotherapy tumor response rate (Phase II) [ Designated as safety issue: No ]
  
• Progression-free survival (Phase II) [ Designated as safety issue: No ]
  

OBJECTIVES:

• Determine the maximum tolerated dose of temozolomide in combination with methotrexate and rituximab before fractionated whole brain radiotherapy in patients with primary central nervous system lymphoma.
• Compare the 2-year survival rate of patients receiving this chemotherapy regimen before radiotherapy and temozolomide after radiotherapy to that of patients treated on protocol RTOG-9310.
• Compare the tumor response rates of patients treated with this chemotherapy regimen before radiotherapy to that of patients treated on RTOG-9310.
• Determine the progression-free survival of patients treated with this regimen.
• Determine the acute and long-term neurologic toxicity of this regimen in these patients.
• Determine the quality of life of patients treated with this regimen.

OUTLINE: This is a phase I dose-escalation study of temozolomide in combination with methotrexate and rituximab before radiotherapy, followed by a phase II study.

Phase I

• Pre-radiotherapy chemotherapy: Patients receive rituximab IV 3 days prior to the first course of methotrexate. Patients then receive methotrexate IV over 4 hours on weeks 1, 3, 5, 7, and 9 (for a total of 5 doses). Patients also receive oral temozolomide daily for 5 days on weeks 4 and 8.

Cohorts of 3-6 patients receive escalating doses of temozolomide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose at which no more than 0 of 3 or 1 of 6 patients experience dose-limiting toxicity.

• Radiotherapy: Patients undergo whole brain radiotherapy daily for 5 days on weeks 11, 12, and 13.
• Post-radiotherapy chemotherapy: Patients receive oral temozolomide once daily on days 1-5 beginning at week 14. Treatment repeats every 28 days for 10 courses in the absence of unacceptable toxicity.

Phase II

• Patients receive treatment as in phase I at the MTD of temozolomide. Treatment continues in the absence of unacceptable toxicity.

Quality of life is assessed at baseline, at weeks 10 and 13, every 2 months during post-radiotherapy temozolomide therapy, at the end of therapy, and then every 3 months for 2 years, every 6 months for 3 years, and annually for 5 years.

Patients are followed every 3 months for 2 years, every 6 months for 3 years, and then annually for 5 years.

PROJECTED ACCRUAL: A total of 52-64 patients (up to 18 patients for phase I and 46 patients for phase II) will be accrued for this study within 19 months.

DISEASE CHARACTERISTICS:

• Cytologically confirmed primary CNS lymphoma

  • Based on positive biopsy, cerebrospinal fluid, or vitreous cytology (in association with measurable intraparenchymal tumor)
  • B-cell type
  • CD20+ disease
  • Cytology must demonstrate lymphoma OR an immunohistochemical diagnosis of malignant lymphocytes with a monoclonal lymphocytic population
• No evidence of systemic lymphoma

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• Zubrod 0-2

Life expectancy

• At least 8 weeks

Hematopoietic

• Absolute granulocyte count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic

• Bilirubin no greater than 2 times upper limit of normal (ULN)
• AST no greater than 2 times ULN
• Alkaline phosphatase no greater than 2 times ULN
• No active hepatitis B

Renal

• Creatinine clearance at least 50 mL/min
• No renal insufficiency

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• HIV negative
• No other malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix
• No history of idiopathic sensitivity to any of the drugs in this study
• No active infection
• No known anaphylaxis or IgE-mediated hypersensitivity to murine proteins or to any component of rituximab

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No prior chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• No prior radiotherapy to the brain, head, or neck

Surgery

• No prior organ transplantation