rituximab + methotrexate + cytarabine

This is a combination chemotherapy regimen consisting of rituximab, methotrexate, and cytarabine. It is primarily used in the treatment of primary central nervous system lymphoma (PCNSL), especially as an induction or consolidation therapy. Rituximab is a monoclonal antibody targeting CD20 on B cells, leading to their depletion via immune-mediated mechanisms. Methotrexate is an antimetabolite that inhibits dihydrofolate reductase, disrupting DNA synthesis and cell replication. Cytarabine is a nucleoside analog that interferes with DNA synthesis during the S-phase of the cell cycle. The combination aims to maximize anti-lymphoma efficacy by targeting malignant B cells through both immunological and cytotoxic mechanisms[3][5][6]. This regimen may be used alone or as part of more complex protocols (such as MATRix when combined with thiotepa) for PCNSL.