Radioimmunotherapy: Clinical results and dosimetric considerations

Radiolabeled antibodies for cancer therapy are being investigated in clinical trials in more than 30 centers. ¹³¹Iodine-labeled antibody (Ab) therapy of solid tumors has produced few responses when given alone. When given in conjunction with chemotherapy and external beam therapy in hepatoma patients, objective responses have occurred. Because of the short range of ¹³¹I, ⁹⁰Y and ¹⁸⁶Re are being studied and objective responses have occurred in patients without the addition of other therapies. ¹³¹I-labeled Ab therapy of lymphoma, a radioresponsive tumor, has produced a much higher objective response rate than in other solid tumors. Regional RIT has not been shown to offer a definite advantage over the intravenous route. Tumor doses have generally been less than 2000 cGy per treatment with some tumors receiving higher doses. The bone marrow is the dose-limiting organ for RIT and marrow cryopreservation with subsequent reinfusion may prove useful.