Timing of autologous stem cell transplantation and induction response in central nervous system lymphoma.

Primary and secondary central nervous system lymphomas (PCNSL and SCNSL, respectively) are aggressive non-Hodgkin lymphomas with high relapse risk. Methotrexate rarely achieves durable remission, necessitating combination therapy or consolidation. Although high-dose busulfan and thiotepa (BuTT) conditioning followed by autologous stem cell transplantation (ASCT) is a promising consolidation strategy, the optimal timing and real-world outcomes of ASCT remain unclear. We retrospectively analyzed 12 patients (eight with PCNSL and four with SCNSL) treated with BuTT/ASCT at a single center between 2019 and 2024. Nine patients underwent upfront ASCT shortly after achieving complete remission with rituximab, methotrexate, procarbazine, and vincristine and remained in remission at a median follow-up of 681 days (range, 147-1322 days). Three patients (two with PCNSL and one with SCNSL) who underwent salvage ASCT following multiple prior therapies experienced early relapse (51-125 days post-ASCT) and died of their disease. BuTT/ASCT is highly effective when administered promptly after remission, whereas salvage ASCT after multiple therapies is associated with poor outcomes. Timely clinical decision-making and upfront consolidation may be key to optimizing the therapeutic benefits of ASCT in CNSL, although further validation is warranted.