Real-world comparison of BTK inhibitors and lenalidomide as first-line maintenance in primary CNS lymphoma: a multi-center retrospective study.

[BACKGROUND] Primary central nervous system lymphoma (PCNSL) is a rare, aggressive malignancy presenting significant therapeutic challenges. Optimal maintenance therapy following initial remission remained debated.

[METHODS] We conducted a multicentre, real-world study comparing BTK inhibitors (BTKi, n = 23) versus lenalidomide (n = 48) as maintenance in 71 newly diagnosed PCNSL patients in remission.

[RESULTS] With a median follow-up of 41.2 months, median overall survival (OS) and progression-free survival (PFS) remained unachieved for the total cohort. BTKi maintenance was associated with significantly superior PFS compared with lenalidomide (not achieved vs. 61.0 months; p = 0.016), with a substantially higher 6-year PFS rate (91.3% [95% CI: 69.5-97.7%] vs. 41.5% [95% CI: 23.8-58.4%], P < 0.001). This benefit was confirmed as an independent favourable prognostic factor in multivariate analysis (HR = 0.22, 95% CI: 0.05-0.87; P = 0.036). While PFS differed significantly, OS was comparable between the two groups. It is notable that 86.4% of patients who relapsed during lenalidomide maintenance transitioned to BTKi-based regimens, achieving a substantial second-line PFS (median 20.5 months). Furthermore, BTKi benefit was stable regardless of maintenance duration. In contrast, lenalidomide maintenance showed significant heterogeneity: optimal cutoffs for duration were identified separately for PFS (21.3 months) and OS (6.3 months). No treatment-related deaths occurred.

[CONCLUSION] These data suggest that BTKi maintenance is a highly effective strategy for newly diagnosed PCNSL, offering prolonged progression-free survival compared with lenalidomide. The significant efficacy of BTKi in both first-line maintenance and second-line salvage settings provides a preliminary basis for re-evaluating current treatment paradigms, pending confirmation by prospective trials.