Active specific immunotherapy in hepatic metastasis

The immune system takes note of the presence of a malignant tumor but in most cases an effective defense reaction is hardly likely to come about. In patients with a solid tumor a tumor-directed immune response will usually be manifested as sensitization of T-lymphocytes to different tumor associated antigens (TAA). There is hope, however, that deeper insights into the mechanisms which ensure the selective clonal expansion and differentiation of antigen-sensitized lymphocytes and an appropriate stimulation of tumor specific effector cells will make it possible to inhibit or at least to impede the outgrowth of metastases following the surgical resection of the primary tumor. Active specific immunization (ASI) is one way to activate tumor specific T-or B-lymphocytes. In this paper, we give a short survey on the state of the art of ASI, outline newer approaches to improve its effectiveness and summarize results of clinical studies with ASI in patients with malignant melanoma or colorectal carcinoma. Among the epidemiologically important tumors, malignant melanoma is that one which seems to be most immunogenic and therefore has been studied intensively. The reason we refer to colorectal carcinoma is that we ourselves have some preliminary experiences with ASI in patients with colon carcinoma.