The role of radioimmunotherapy in bone marrow transplantation

Radioimmunotherapy offers an exciting new therapeutic modality for patients with recurrent hematologic malignancies and solid tumors resistant to conventional chemotherapy. In this review, a brief overview of tumor radiobiology as well as various obstacles to treatment is presented. Early radiolabeled antibody trials documented myelosuppression as the dose-limiting toxicity. Ongoing trials in solid tumors and hematologic malignancies are testing the hypothesis that myeloablative doses of radiation in conjunction with hematopoietic stem cell rescue will improve long-term survival. For solid tumors, there are many barriers to achieving this goal. The most encouraging trials in metastatic breast cancer have documented significant symptomatic relief and a 50% partial response in patients. In contrast, trials involving hematologic malignancies have produced more impressive results. With a median follow-up of 33 months, 67% of patients with recurrent acute myelogenous leukemia or myelodysplasia treated with radiolabeled antibodies, total-body irradiation, and high-dose chemotherapy remain disease free. Alone, myeloablative doses of radioimmunotherapy have documented a 41% complete response in patients with Hodgkin's disease. Seattle trials with recurrent non-Hodgkin's lymphoma have demonstrated objective responses in 90% of patients, complete responses in 85% of patients, a progression-free survival of 62%, and an overall survival of 93% with a median follow-up of 2 years.