Several approaches to increase
tumor cell immunogenicity and anti-
tumor T-cell reactivity have been reviewed. In contrast to unspecific immune stimulation, the activation of specific T-cell reactivity can lead to long-lasting anti-
tumor immunity. In several instances, immunization with modified
tumor cells led to the induction of
tumor immunity against the original non-modified
tumor cells. In our own studies two types of approaches were also effective with the highly metastatic mouse
tumor line ESb which carries a weak
tumor associated
antigen. Postoperative immunization with either virus modified ESb cells or with mutagenized variants of ESb cells led to the survival of a significant proportion of the treated animals. These animals had been cured of their
micrometastases and developed long lasting anti-
tumor immunity. It is hoped that such modified
tumor cells could become useful
reagents for
tumor immunotherapy, especially in situations where the
tumor burden is low. Future efforts should be directed towards testing the effectiveness of immunogenic modified
tumor variants in combination with surgery or
chemotherapy for treatment of micrometatases.