Comparative Outcomes of Consolidation Strategies After R-MVP Induction in Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System.

BACKGROUND: The optimal consolidation strategy following high-dose methotrexate (MTX)-based induction in primary central nervous system lymphoma (PCNSL) remains controversial. This study compared real-world outcomes of different consolidation modalities in patients responsive to rituximab, MTX, vincristine, and procarbazine (R-MVP) induction chemotherapy.

METHODS: We retrospectively analyzed 296 newly diagnosed PCNSL patients treated with R-MVP between 2008 and 2023. Among 290 evaluable patients, the overall response rate (ORR) was assessed, and survival outcomes were evaluated by Kaplan-Meier and Cox regression analyses. Propensity score matching (PSM) was performed to compare autologous stem-cell transplantation (ASCT) and whole-brain radiotherapy (WBRT).

RESULTS: The ORR was 89.7%, with 71.7% achieving complete response (CR) or complete response unconfirmed (CRu) and 17.9% partial response (PR). Of 260 responders, 190 received consolidation: WBRT (40.8%), ASCT (20.0%), or non-myelosuppressive chemotherapy (NMC; 12.3%). After a median follow-up of 45.3 months, median progression-free survival (PFS) and overall survival (OS) for responders were 65.8 (95% CI 50.7-80.8) and 84.6 months (95% CI 66.5-102.7), respectively. ASCT yielded the most favorable survival (median PFS not reached), followed by WBRT (70.8 months), whereas NMC and no-consolidation groups showed significantly inferior PFS (22.9 and 40.1 months, p < 0.001). OS showed a similar trend (p = 0.006). On multivariable analysis, elevated LDH and consolidation type were independent predictors of PFS, whereas age and consolidation type were significant prognostic factors for OS. In the PSM cohort (ASCT vs. WBRT, n = 52 each), median PFS was not reached for ASCT versus 90.0 months for WBRT (p = 0.050); OS was not reached versus 97.9 months (p = 0.160).

CONCLUSIONS: ASCT was associated with the most durable survival among consolidation strategies after R-MVP induction. These findings, derived from a large real-world, multi-institutional cohort, support ASCT as the preferred consolidation for eligible patients while underscoring the heterogeneity of current practice and the need for prospective validation.