CTNI-38. SINGLE-CENTER COMPARATIVE ANALYSIS ABOUT OUTCOMES OF MULTI-AGENTS CHEMOTHERAPY FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA; R-MPV SHOWED A FAVOR RESULT

Abstract BACKGROUND Primary central nervous system lymphoma (PCNSL) is a malignant tumor in the brain, spinal cord, and eyes. Radiotherapy may cause delayed leukoencephalopathy so that the first-line treatment is methotrexate (MTX)-based multi-agent chemotherapy. We had used the Bonn protocol based on MTX and cytarabine, but since 2020, we have adopted the R-MPV protocol. This study analyzes the outcomes of patients treated initially at our institution. METHODS AND RESULTS We reviewed 57 out of 88 newly diagnosed PCNSL patients treated with chemotherapy alone between December 2005 and January 2023. Initial treatments included the Bonn protocol in 25 patients (12 with rituximab, forming R-Bonn) and R-MPV in 26 patients. High-dose chemotherapy with peripheral blood stem cell transplantation (PBSCT) was given as consolidation in 4 Bonn and 9 R-MPV patients. The Bonn protocol was completed by 20 patients (80%) with a complete response (CR) in 19 (76%). The R-MPV protocol was completed by 23 patients (88%) with CR in 22 (85%). Post-treatment outcomes were compared using survival analysis. Median progression-free survival (mPFS) had not been reached in the R-MPV group and was significantly better than 33.1 months in the Bonn protocol and 58.6 months in the R-Bonn protocol (log-rank test; p=0.0296, 0.0036). Overall survival (OS) did not show significant differences. PBSCT’s impact on outcomes suggested improvement in PFS and OS after R-MPV, but this was not statistically significant. DISCUSSION We examined the efficacy of different chemotherapy regimens for PCNSL at our institution. The R-MPV protocol showed superior completion rates, response rates, and treatment efficacy. Consolidation with PBSCT may improve outcomes, though further investigation with more cases and longer observation is necessary.