The notable outcomes of modified thiotepa-based conditioning followed by autologous stem cell transplantation in primary central nervous system lymphomas: A real-life pilot study

High-dose chemotherapy followed by autologous stem cell transplantation (HDC–ASCT) is a promising approach for patients with primary central nervous system lymphoma (PCNSL). Encouraging results have been reported with thiotepa-based conditioning; however, there is currently no consensus on the optimal conditioning regimens. To improve the tolerance and efficacy of ASCT with thiotepa-based conditioning, this retrospective, single-arm, pilot study was conducted, including 12 PCNSL patients who received ASCT with modified thiotepa-based conditioning regimens. It was found that 6 patients received ASCT as a first-line consolidation in complete response (CR)/partial response (PR) state, and 6 cases underwent salvage treatment. Among the patients, 7 (58.3%) received the mTBC conditioning regimen, 4 (33.3%) received TT-Bu, and one patient was incorporated with chimeric antigen receptor T-cell (CAR-T) cell infusion with the TT-Cy regimen. All patients achieved sustained neutrophil recovery within a median of 9 (range, 7–12) days and platelet engraftment within a median of 10 (range, 6–12) days. Furthermore, all patients were in CR status at the initial efficacy evaluation following ASCT. The main complications during hospitalization were febrile neutropenia (83.3%) and diarrhea grade 3 (50.0%). No transplantation- related mortality occurred. Maintenance therapy post-ASCT was administered in 11 cases, demonstrating its effectiveness and favorable tolerability. The estimated 1- and 3-year progression-free survival (PFS) following ASCT were 80.0% and 53.3%, respectively, while the estimated 1-and 3-year overall survival (OS) were both 100%. This study presented the modified thiotepa-based conditioning regimens and confirmed their safety and efficacy with ASCT for PCNSL patients.