The modified hyper-CVAD regimen is a combination of chemotherapy drugs including cyclophosphamide, vincristine, Adriamycin, dexamethasone and pegylated asparaginase given together for one "course" of treatment. This alternates with a course or combination of the chemotherapy drugs methotrexate, cytarabine (ara-C), and pegylated asparaginase. Rituximab is a protein (monoclonal antibody) that attaches to the surface of the leukemia or lymphoma cells, which have a marker, called "CD20".