Primary central nervous system lymphoma (PCNSL) is a rare aggressive non-Hodgkin lymphoma characterized by early relapses and poor outcomes, with a 5-year survival rate of 20% to 30%.1,2 The current standard of care consists of induction therapy using high-dose methotrexate-based chemotherapy, followed by consolidation therapy with either whole-brain radiotherapy (WBRT) or autologous hematopoietic cell transplant (AHCT). Despite comparable outcomes with WBRT and AHCT, significant cognitive impairment has been observed in patients following WBRT.1,2 Owing to this complication, clinical studies have increasingly focused on AHCT as consolidative therapy, with particular examination of the optimal conditioning chemotherapy regimen. Early efforts used the well-established conditioning regimen of carmustine, etoposide, cytarabine and melphalan (BEAM), and more recent trials have used thiotepa-based conditioning, either alone or in comparison with BEAM, owing to thiotepa’s superior CNS penetration, because components of the BEAM regimen do not effectively cross the blood-brain barrier.1-6