rituximab + Hyper-CVAD + methotrexate + cytarabine + ibritumomab tiuxetan

This regimen is a multi-agent chemoimmunotherapy combination designed for aggressive B-cell malignancies, particularly in relapsed or high-risk settings. It consists of: - **rituximab**, a chimeric monoclonal antibody targeting CD20 on B-cells, mediating cell death via antibody-dependent and complement-dependent cytotoxicity; - **Hyper-CVAD**, a chemotherapy backbone alternating between cycles of cyclophosphamide, vincristine, doxorubicin, dexamethasone (A cycles), and high-dose methotrexate plus cytarabine (B cycles); - additional **methotrexate** and **cytarabine** for intensification and CNS prophylaxis; - **ibritumomab tiuxetan**, a radioimmunotherapy agent (anti-CD20 antibody conjugated to Yttrium-90), delivering cytotoxic radiation specifically to CD20-positive B cells. This combination is employed in certain cases of acute lymphoblastic leukemia (ALL), Burkitt lymphoma, and relapsed/refractory non-Hodgkin lymphoma. The addition of rituximab and ibritumomab tiuxetan enhances antitumor activity via both immunologic and radiopharmaceutical mechanisms[1][3].