Autologous stem cell transplantation after conditioning with yttrium-90 ibritumomab tiuxetan plus BEAM in refractory non-Hodgkin diffuse large B-cell lymphoma: results of a prospective, multicenter, phase II clinical trial

Lymphoma patients with persistent disease undergoing autologous transplantation have a very poor prognosis in the rituximab era. The addition of radioimmunotherapy to the conditioning regimen may improve the outcome for these patients. In a prospective, phase 2 study, we evaluated the safety and efficacy of the addition of Y-90-ibritumomab tiuxetan to the conditioning chemotherapy in patients with refractory diffuse large B-cell lymphoma. Thirty patients with induction failure (primary refractory; n=18) or refractory to salvage immunochemotherapy at relapse (n=12) were included in the study. The median age of the patients was 53 years (range, 25-67). All patients were given Y-90-ibritumomab tiuxetan at a fixed dose of 0.4 mCi/kg (maximum dose 32 mCi) 14 days prior to the preparative chemotherapy regimen. Histological examination showed that 22 patients had de novo diffuse large B-cell lymphoma and eight had transformed diffuse large B-cell lymphoma. All patients had persistent disease at the time of transplantation, with 25 patients considered to be chemorefractory. The median time to neutrophil recovery (>500 white blood cells/mu L) was 11 days (range, 9-21), while the median time to platelet recovery (>20,000 platelets/mu L) was 13 days (range, 11-35). The overall response rate at day +100 was 70% (95% CI, 53.6-86.4) with 60% (95% CI, 42.5-77.5) of patients obtaining a complete response. After a median follow-up of 31 months for alive patients (range, 16-54), the estimated 3-year overall and progression-free survival rates are 63% (95% CI, 48-82) and 61% (95% CI, 45-80), respectively. We conclude that autologous transplantation with conditioning including Y-90-ibritumomab tiuxetan is safe and results in a very high response rate with promising survival in this group of patients with refractory diffuse large B-cell lymphoma with a very poor prognosis.