Impact of Thiotepa-Based Autologous Hematopoietic Cell Transplantation in Primary Central Nervous System Lymphoma in First Complete Remission: A University of California Hematologic Malignancies Consortium Retrospective Analysis

The choice between nonmyeloablative chemotherapy (NMA-C) or autologous hematopoietic cell transplantation (autoHCT) as consolidation in primary central nervous system lymphoma (PCNSL), and timing of autoHCT differs among centers. We aimed to clarify these points.We retrospectively analyzed PCNSL adult patients who received consolidation in CR1 or underwent autoHCT during their treatment course. Cohort A included those who underwent autoHCT in CR1, cohort B included those who underwent NMA-C in CR1, and cohort C included patients who underwent autoHCT in CR2+. We compared cohorts A and B, and cohorts A and C. The primary endpoint was overall survival (OS), and secondary endpoints were progression-free survival (PFS), treatment-related mortality (TRM) and cumulative incidence of relapse (CIR).36 patients were included in cohort A, 30 in cohort B, and 14 in cohort C. The 5-year OS for cohorts A vs B and vs C were 90.7% vs 62.8% (P = .045) and vs 77.9% (P = .32), respectively. The 5-year PFS from diagnosis for cohorts A vs B was 87.8% vs 37.3% (P < .001). The 5-year PFS from autoHCT for cohorts A vs C was 87.6% vs 58.4% (P = .023). The 5-year TRM and CIR in cohorts A vs B was 9.4% vs 9.5% (P = .674), and 2.9% vs 53.2% (P < .001), respectively. The 5-year TRM and CIR in cohorts A vs C from the time of autoHCT was 9.5% vs 22.1% (P = .188), and 2.9% vs 19.5% (P = .104), respectively.Despite the limitations, thiotepa-based autoHCT in CR1 appears to improve outcomes in eligible patients with PCNSL.