Yttrium-90-ibritumomab tiuxetan in combination with intravenous busulfan, cyclophosphamide, and etoposide followed by autologous stem cell transplantation in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma

Background Radiolabelled immunotherapy agents have an increasingly significant role in autologous stem cell transplantation (ASCT) by improving the tolerability and increasing the efficacy of the conditioning regimen, thereby reducing the relapse risk. We evaluated the efficacy and safety of yttrium-90-ibritumomab tiuxetan ((90)Y-ibritumomab) combined with intravenous busulfan, cyclophosphamide, and etoposide (Bu/Cy/E) followed by ASCT in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Methods Each patient received a single dose of (90)Y-ibritumomab (0.4 mCi/kg on day -14) with Bu/Cy/E as a conditioning regimen. Results The patient cohort consisted of 19 individuals (ten males), of median age 51 years (range, 25-63 years). Sixteen patients had received two or more chemotherapy regimens before transplantation. Histologies were diffuse large B-cell (n = 14), follicular (n = 2), mantle cell (n = 2), and Burkitt lymphoma (n = 1). All patients engrafted. The median time to neutrophil engraftment was 10 days and time to platelet engraftment was 10 days. Nineteen patients were evaluable for response. The objective overall response rate was 84.2% (16/19): continued CR, 36.8% (7/19); induced CR, 36.8% (7/19); and PR, 10.5% (2/19). With a median follow-up of 29.4 months (13.4-36.6), the estimated 3-year overall survival and event-free survival rates were 52.6% (95% confidence interval [CI] 45.8-59.4) and 26.3% (95% CI 19.8-32.8), respectively. Adverse events were similar to those seen historically with Bu/Cy/E alone, and there were no treatment related deaths. Conclusion In conclusion, (90)Y-ibritumomab with Bu/Cy/E and ASCT is feasible in patients with relapsed or refractory B-cell NHL, without increased toxicity.