Future trends in radioimmunotherapy

Abstract

Radioimmunotherapy (RIT) is currently approved in the United States only for use in low-grade follicular or transformed non-Hodgkin's lymphoma. One of the major issues in the construction of new clinical trials is deciding in which phase of disease RIT should be applied: upfront, as part of first-line treatment, in relapsed/refractory patients, in bulky or 'minimal residual disease', or in patients failing 'cold' antibody treatment? An important consideration for future trends in RIT is how the efficacy of RIT can be increased, while limiting toxicity. To increase efficacy, it is important to understand the reasons why RIT can fail in some patients. Efficacy might be increased by improving tumor to normal organ ratios of antibody (using synthetic clearing agents to clear nontumor-bound antibody from the bloodstream), or by combining RIT with radiosensitizers, such as fludarabine. Methods of reducing toxicity are also being investigated (eg, by splitting the full dose of RIT, or using biological prognostic factors to identify patients who are likely to experience myelosuppression). Biological prognostic factors may also predict disease response and can be used to stratify patients into risk groups at diagnosis, which may predict outcome according to a limited set of prognostic factors. It is also important to establish the effect of prior chemotherapy regimens on RIT, and likewise to determine to what extent RIT compromises subsequent chemotherapy treatment. This article attempts to address these issues and anticipate future trends in RIT.