Current status and future perspectives for yttrium-90 (⁹⁰Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma

Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on ⁹⁰Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose ⁹⁰Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose ⁹⁰Y-ibritumomab tiuxetan as the sole myeloablative agent, prior to autologous SCT, and also ⁹⁰Y- ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes.