The development of successful approaches to immunotherapy is dependent upon proper consideration of the pathobiology of metastasis and the establishment of a better scientific understanding of the principles of biological response modification. The studies we have undertaken are aimed at the rational development of a preclinical data base to help provide this understanding. Ultimately, these studies will be correlated with clinical trials to assess the predictive value of the preclinical screen. We anticipate that the testing of biological response modifiers (BRMs) in a controlled but evolving system will help eliminate arbitrary decisions on the preparations and use of a given BRM and ultimately will contribute to the development of novel approaches for the treatment of disseminated cancer. Immunotherapy alone or in combination with other therapeutic modalities is an area of rapid evolution with tremendous potential as an adjuvant therapy of disseminated cancer.