Matched-Cohort Analysis of Autologous Hematopoietic Cell Transplantation with Radioimmunotherapy versus Total Body Irradiation–Based Conditioning for Poor-Risk Diffuse Large Cell Lymphoma

We conducted a matched-cohort analysis of autologous transplant conditioning regimens for diffuse large cell lymphoma in 92 patients treated with either radioimmunotherapy (RIT) or total body irradiation (TBI)–based conditioning regimens. The RIT regimen consisted of 0.4 mCi/kg of 90Y-ibritumomab tiuxetan plus BEAM (BCNU, etoposide, cytarabine, melphalan). The TBI-based regimen combined fractionated TBI at 1200 cGy, with etoposide and cyclophosphamide. Five factors were matched between 46 patient pairs: age at transplant ±5 years, disease status at salvage, number of prior regimens, year of diagnosis ±5 years, and year of transplantation ±5 years. Patients in the TBI group had higher rates of cardiac toxicity and mucositis, whereas Z-BEAM patients had a higher incidence of pulmonary toxicity. Overall survival at 4 years was 81.0% for the Z-BEAM and 52.7% for the TBI group (P = .01). The 4-year cumulative incidence of relapse/progression was 40.4% and 42.1% for Z-BEAM and TBI, respectively (P = .63). Nonrelapse mortality was superior in the Z-BEAM group: 0% compared with 15.8% for TBI at 4 years (P < .01). Our data demonstrate that RIT-based conditioning had a similar relapse incidence to TBI, with lower toxicity, resulting in improved overall survival, particularly in patients with ≥2 prior regimens.