Radioimmunotherapy of non-Hodgkin's lymphomas

The availability of active monoclonal antibodies has altered the treatment paradigms for patients with non-Hodgkin's lymphomas (NHL). Nevertheless, some patients do not respond, while almost all of the others eventually relapse and require additional treatment. Thus, more effective alternatives are needed. Radioimmunotherapy (RIT) is an attractive option because of the inherent radiosensitivity of most NHL. Yttrium-90 ibritumomab tiuxetan and iodine-131 tositumomab are the first two radioimmunoconjugates currently available for clinical use. These agents appear comparably active in patients with follicular and low-grade NHL, after failure following chemotherapy and/or rituximab. Activity has also been demonstrated against other histologies, including diffuse large B-cell NHL, mantle cell NHL, and transformed NHL. Toxicities primarily include myelosuppression, with a potential risk of treatment-associated myelodysplastic syndrome and acute myelogenous leukemia. Current clinical trials are attempting to optimize the use of these agents by evaluating them earlier in the course of the disease, and sequenced with a variety of chemotherapy regimens. Hopefully, the rational development of RIT will lead to a prolongation of survival for patients with NHL.