- Courses 2, 4, 6, and 8: Patients receive rituximab IV on day 1 (courses 2, 4, and 6 only); high-dose methotrexate IV over 24 hours on day 2; high-dose cytarabine IV over 2 hours twice a day on days 3-4; oral leucovorin calcium 4 times a day on days 3-10; and G-CSF SC daily beginning on day 5 and continuing until blood counts recover.