CTNI-23. R-MPV FOLLOWED BY MAINTENANCE MPV IN ELDERLY PATIENTS WITH NEWLY DIAGNOSED PRIMARY CNS LYMPHOMA

Abstract BACKGROUND The addition of high-dose methotrexate (HD-MTX)-based chemotherapy to whole-brain radiotherapy (WBRT) has improved the prognosis of primary CNS lymphoma (PCNSL). However, high rates of neurotoxicity following WBRT, particularly in elderly patients, have raised interest in chemotherapy-only treatment strategies. Nonetheless, omitting radiotherapy may compromise disease control. Therefore, developing novel therapeutic approaches for elderly patients with PCNSL (ePCNSL) is essential. In ePCNSL, for those who are unable to tolerate WBRT or high-dose chemotherapy with autologous stem cell transplantation as consolidation, maintenance chemotherapy may serve as a feasible approach after an initial response. We treated ePCNSL with induction immunochemotherapy consisting of rituximab (R), HD-MTX, procarbazine, and vincristine (R-MPV), followed by maintenance chemotherapy with MPV. This retrospective study investigated the prognosis of ePCNSL after induction, consolidation, and maintenance chemotherapy with (R-)MPV. MATERIALS AND METHODS Patients with newly diagnosed ePCNSL (median age, 73 years; median KPS, 60) received biweekly R-MPV for six cycles (induction) followed by monthly R-MPV for two cycles (consolidation). Subsequent treatment was based on radiological response. Patients achieving CR received maintenance MPV every two months for two years. For patients with PD, immunochemotherapy was discontinued, and either a Bruton’s tyrosine kinase inhibitor or WBRT was initiated immediately. RESULTS Of the 42 patients with ePCNSL, 38 were eligible for radiographic evaluation. After induction and consolidation chemotherapy, 30 patients (78.9%) achieved a CR, 6 (15.8%) had a PR, and 2 (5.3%) had a PD. The median event-free survival (EFS) was 31.2 months. The median OS was 48.9 months for the entire cohort. KPS and MMSE scores improved during induction chemotherapy and were maintained during maintenance chemotherapy. Treatment-related mortality was 4.7%, with one renal failure and one myocardial infarction. CONCLUSION These findings suggest that maintenance chemotherapy with MPV may improve performance status, neurocognitive function, and overall prognosis in elderly patients with PCNSL.