Reduced Intensity Conditioning Prior Autologous Stem Cell Transplantation in Elderly <scp>DLBCL</scp> Patients

High-dose chemotherapy (HDCT) followed by autologous stem cell transplantation (ASCT) is widely used in patients with diffuse large B-cell lymphoma. HDCT/ASCT is associated with increased morbidity in elderly/unfit patients. We retrospectively evaluated the use of reduced intensity conditioning in DLBCL patients. Our study included 146 patients aged 60 years and older treated at our institution between 2005 and 2019; 86 patients received standard intensity conditioning (SI group) with BEAM or TEAM (BCNU or thiotepa, etoposide, cytarabine, melphalan). Sixty patients received reduced intensity high-dose conditioning (RI group) with BM (BCNU, melphalan, 43.3%), TM (thiotepa, melphalan, 16.7%), BCNU or busulfan thiotepa (38.4%), or bendamustine melphalan (1.7%). Median follow-up was 62.4 months. We observed comparable toxicities in the SI and RI groups. The cumulative incidence of relapse at 3 years was higher in the RI group (30.8% vs. 23.4%, p = 0.034). There was no difference in nonrelapse mortality (NRM). In univariate analyses, SI vs. RI conditioning resulted in superior progression-free survival (PFS) (HR 1.80 CI 1.11-2.92, p = 0.017) but not in superior overall survival (OS) (HR 1.48 CI 0.86-2.56, p = 0.152). On multivariate analysis, we observed no difference in PFS (HR 0.74 CI 0.40-1.38, p = 0.345) and a trend toward better OS with RI conditioning (HR 0.45 CI 0.22-0.94, p = 0.032). Age 60-69 versus ≥ 70 years and remission prior to ASCT were the only factors predicting better PFS. Factors associated with better OS were RI conditioning, age 60-69 versus ≥ 70 years, ECOG 0 versus ≥ 1 performance status, bulky disease, and prior lines 1 versus ≥ 2. In conclusion, RI conditioning prior to ASCT may be feasible in elderly patients and led to a comparable outcome when corrected for several significant confounders.