Methods Modifications of the US NCI regimen include rituximab (R), cyclophosphamide reduction [800 mg/m2 x 2 days], vincristine 2 mg cap, methotrexate (mtx) 3000 mg/m2, dual chemotherapy lumbar punctures and IVAC infusion (high risk pts). Antibiotic prophylaxis & growth factor support specified, 100% grade IV hematopoietic toxicities in the original regimen. HAART therapy at the discretion of the local MD. Pathology review included CD20, CD10, BCL2, BCL6, p53, Ki67, BLIMP1, IRF4/ MUM1 and EBV EBER. (Table 1)