• Immediate toxicity (incidence of reactions to glucarpidase) as determined by the NCI CTC [ Designated as safety issue: Yes ]
  
• Incidence and severity of renal dysfunction as determined by the NCI CTC [ Designated as safety issue: Yes ]
  
• Incidence and severity of mucositis as determined by the NCI CTC and WHO mucositis grading scale [ Designated as safety issue: Yes ]
  
• Incidence and severity of CNS toxicity and neurocognitive changes taken from patients' medical records and measured using the Mini-Mental State questionnaire and MRI data [ Designated as safety issue: Yes ]
  

• Hematological toxicity (i.e., number of courses of therapy associated with neutrophils < 0.5 x 10e9/L or platelets < 50 x 10e9/L as measured by routine blood counts) [ Designated as safety issue: Yes ]
  
• Incidence of infection (i.e., number of days with fever ≥ 38 C° measured by clinical examination and days of intravenous antibiotics taken from patients' medical records) [ Designated as safety issue: Yes ]
  
• Number of inpatient days taken from patients' medical records [ Designated as safety issue: No ]
  
• Disease response and remission rates measured by serial MRI scanning (and eye examination and lumbar puncture if necessary) [ Designated as safety issue: No ]
  
• Disease outcome, time to progression, and overall survival at 2 years from start of therapy measured by clinical examination and serial MRI scanning [ Designated as safety issue: No ]
  
• Relative dose intensity [ Designated as safety issue: No ]
  
• Methotrexate levels post-glucarpidase (expressed as a clinically important reduction, which is defined as a methotrexate level of < 1 μmol/L in all post-glucarpidase samples) [ Designated as safety issue: No ]
  
• Incidence of antibodies to glucarpidase measured serologically at the start of each methotrexate course and at follow-up visits if present during therapy [ Designated as safety issue: No ]
  

OBJECTIVES:

Primary

• To determine the dose-limiting toxicity of methotrexate (MTX) when given in combination with glucarpidase in patients with newly diagnosed primary CNS lymphoma (PCNSL).
• To determine the incidence of immediate reactions related to the use of glucarpidase in these patients.
• To define a safer, more practical, and simpler regimen for delivering multiple courses of high-dose MTX using glucarpidase and 'short' leucovorin calcium rescue in these patients.
• To monitor quality of life and mental function during and after therapy in these patients.

Secondary

• To use this regimen as a platform for phase III studies in PCNSL.
• To record disease response, duration of response, and overall survival of patients treated with this regimen.

OUTLINE: This is a multicenter, dose-escalation study of high-dose methotrexate (HD-MTX).

Patients receive HD-MTX IV over 4 hours on day 1. Beginning 22 hours after the start of HD-MTX, patients receive glucarpidase IV over 15 minutes on day 2 followed by leucovorin calcium orally or IV on days 2-7. Treatment repeats every 14 days for up to 6 courses in the absence of disease progression or unacceptable toxicity.

Within 2-4 weeks after completion of study treatment, patients achieving maximum response are stratified according to age (< 60 years vs ≥ 60 years) and may undergo whole brain radiotherapy (WBRT) once daily, 5 days a week, for 3 to 5 weeks.

Patients undergo blood sample collection periodically to assess glucarpidase antibodies and MTX levels.

Patients are assessed for mucositis incidence and severity periodically, and complete quality of life assessments using the EORTC QLQ-30 questionnaire and the Mini-Mental State questionnaire at baseline, during, and after completion of study.

After completion of study treatment, patients are followed at 6 weeks after WBRT, every 3 months for 1 year, every 4 months for 1 year, every 6 months for 3 years, and then annually thereafter.