Rituximab: mechanisms and applications

Rituximab, a chimeric monoclonal antibody (mAb) which targets the CD20 molecule on the B-cell surface, was the first antibody to be licensed for the treatment of malignancy. This represents the culmination of more than two decades of intensive investigation into the use of mAb in lymphoma. and points the way to a new era of cancer-specific therapy. There are many questions still outstanding about the precise cellular effects of the antibody. but emerging clinical data suggest that it may represent a step forward in the treatment of B-cell malignancies. Unfortunately the application of rituximab is running well ahead of the evidence. with 30 000 patients per annum receiving it in the USA at a cost of over $400 million in 2000, a figure which is rising steeply. As many as 80% of newly diagnosed patients with large cell lymphoma are reported to be receiving treatment including the antibody, despite the absence of any fully published evidence of efficacy in a randomised trial. This situation needs to be corrected as rapidly as possible, and it will be important to complete the trials now underway.