Introduction

Received October 31, 2001; accepted November 14, 2001. I t has been more than two decades since the terms radioimmunodetection and radioimmunotherapy, representing the use of isotopic immunoconjugates for imaging and therapy, respectively, were introduced into the literature. But it has only been in the last few years that this methodology has become of interest to medical and radiation oncologists as a potential new modality of cancer therapy, mainly because good responses have been observed in hematologic tumors, such as non-Hodgkin lymphoma (NHL). This advance has been the subject of a number of recent reviews, as has progress in the radioimmunotherapy of other tumor types. Suffice it to say that we have reached a better understanding of the targeting antibodies and their isotopic conjugates, how to predict anatomic sites of tumors and determine doses of treatment, and the resulting toxicities and responses; and this greater understanding is in part reflected in the contents of these proceedings. A resurgence of interest in cancer radioimmunotherapy has also resulted from the success of unconjugated, or naked, monoclonal antibodies in cancer therapy, especially the introduction of CD20 and HER-2/neu antibodies in the treatment of NHL and breast cancer, respectively. It has been estimated that several hundred clinical trials of investigational antibodies with oncologic indications are underway in the U.S. Various forms of these antibodies are being investigated: unconjugated (or naked), drug conjugates, and radioimmunoconjugates. For many of these agents, including the two naked antibodies that have been approved for commercialization, these advances have been based more on empiric therapy results than on advances in the understanding of the agents’ mechanisms of action. In the case of the CD33 antibody, recently licensed in the U.S. for the treatment of myeloid leukemia, the mechanism is related to the colicheamycin cytotoxic drug conjugated thereto. There has also been recent expectation that at least one radioimmunoconjugate of CD20 antibodies may be approved for the treatment of NHL, thus ushering in the era of radioimmunotherapy as a proven new cancer treatment modality. This would likely be a reassurance to all of the investigators who have been engaged in developing cancer radioimmunotherapy and who have shared their science so generously throughout the proceedings of this conference and former Conferences on Radioimmunodetection and Radioimmunotherapy of Cancer, which were initiated in 1978. –16 Reviewing the current proceedings and those of the prior seven 1193