Biol Blood Marrow Transplant. 2020 Aug 17:S1083-8791(20)30504-8. doi: 10.1016/j.bbmt.2020.08.012. Online ahead of print.
A paucity of randomized phase 3 clinical trials in primary central nervous system lymphoma (PCNSL) has resulted in no uniform consensus on the optimal strategy for consolidation and conditioning regimens for autologous stem cell transplant (ASCT). The last two decades have witnessed a preference for thiotepa-based conditioning regimens due to superior CNS penetration. We retrospectively evaluated outcomes of PCNSL patients who underwent ASCT at Mayo Clinic, Rochester over the last two decades,
and the impact of thiotepa (TT) based conditioning regimens. Fifty-six patients underwent transplant for PCNS lymphoma, with 25 and 31 patients receiving BEAM (non-thiotepa) and BCNU/TT based conditioning, respectively. All patients received high-dose methotrexate based induction therapy. While the BCNU/TT group had higher risk disease features such as high International Extranodal Lymphoma Study Group (IELSG) prognostic score, elevated CSF protein and older patient population, there was no significant difference at 2 years post-transplant in PFS (BEAM 68.0% [46.1-82.5] vs. BCNU/TT, 65.5% [45.2-79.8], (p = 0.99)), or OS (84.0% [62.8-93.7] in the BEAM group vs. 81.6% [61.3-91.9] in the BCNU/TT group, (p = 0.95)). Disease response status before transplant significantly impacted the outcomes as those in complete remission(CR) had an OS at 2 years post-transplant of 94.7% (68.1-99.2) in BEAM group and 90.5% (67.0-97.5) in BCNU/TT group as compared to those in partial response (PR), 57.1% (17.2-83.7) in BCNU/TT group, and 50.0% (11.1-80.4) in the BEAM group, respectively (p <0.0001). Our retrospective cohort adds to the currently available literature and identifies the disease status before transplant as a significant factor impacting survival.