Radio-immunotherapy in low-grade non-Hodgkin's lymphoma.

Radiolabelled monoclonal antibodies (MAbs) differ from naked MAbs because they usually use murine antibodies, however, the next generation will use humanised MAb. Currently two compounds have been widely tested and both have been registered in the USA (yttrium-90 ibritumomab tiuxetan (Zevalin; Idec Pharmaceuticals) and iodine-131 tositumomab formerly known as (131)I-anti-B1 (Bexxar; Corixa Corp.)). The first one has recently been registered in Europe. Both MAbs have activity for the treatment of follicular lymphoma (FL) but few studies have been done outside this indication. In FL, they are associated with a higher response rate than rituximab. Their best indication is currently for patients who are refractory to rituximab but studies are running to define other indications.