rituximab + methotrexate + doxorubicin + prednisone

**Rituximab + methotrexate + doxorubicin + prednisone** is a chemotherapy combination regimen used primarily in clinical trials for aggressive B-cell lymphomas, such as intravascular large B-cell lymphoma (IVLBCL). It integrates rituximab, a monoclonal antibody targeting CD20 on B-cells to induce antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and apoptosis; methotrexate, an antimetabolite inhibiting dihydrofolate reductase to block DNA synthesis; doxorubicin, an anthracycline intercalating DNA and inhibiting topoisomerase II; and prednisone, a glucocorticoid suppressing inflammation and inducing lymphoma cell apoptosis. This specific four-drug mix deviates from standard R-CHOP (which includes cyclophosphamide and vincristine instead of methotrexate) and has been explored in phase 2 trials like PRIMEUR-IVL, often with high-dose methotrexate and intrathecal components for CNS involvement.