Long-Term Outcomes of Autologous Stem Cell Transplant with Thiotepa, Busulfan, and Cyclophosphamide Conditioning for Patients with Central Nervous System Lymphoma

Introduction Central nervous system lymphoma (CNSL) is associated with dismal outcomes and short survival. Treatment of CNSL involves high-dose chemotherapy followed by consolidative autologous stem cell transplant (ASCT). Thiotepa, busulfan and cyclophosphamide (TBC) conditioning improves progression-free survival in CNSL, but further data is needed to evaluate long-term toxicity and survival outcomes. We hereby report our experience in patients with primary and secondary CNSL who received TBC conditioning for ASCT. Methods This is a single institution retrospective review of patients with CNSL who underwent ASCT with TBC conditioning from 2013 to 2023. Data is presented as percentage or median (IQR). Kaplan-Meier curves of survival were used. Primary CNSL was defined as the presence of lymphoma within the CNS with no systemic involvement. Secondary CNSL was defined as the presence of CNS involvement at the time of diagnosis of systemic lymphoma or at relapse. Results Median follow up was 40.6 months (4.1, 75.1). Thirteen patients (68%) were male and 18 (95%) were white. Fifteen patients had secondary CNSL and 4 patients had primary CNSL. The median number of prior lines of therapy was 3 (range 2-5). Most patients underwent ASCT in their second remission or later (58%) (Table 1). Eight patients had neurologic deficits at the time of ASCT. The most common grade 3 or higher adverse events included mucositis (72%), infection (50%) and diarrhea (43%) (Table 2). Median progression free survival was 61.2 months (Figure 1). Median overall survival was 65.3 months (Figure 2). Complete response at the time of ASCT was associated with improved survival compared to partial response (Figure 3). Relapse occurred in 4/19 patients. The most common cause of death was infection (50%) followed by relapsed disease (30%). Conclusion TBC conditioning for ASCT in CNSL is effective but is associated with significant risk of toxicity.