Identification and activation of tumor-reactive cells for adoptive immunotherapy

The use of adoptive immunotherapy to treat cancer has several potential advantages. Although extensive evaluation has been undertaken, issues regarding the source of cells and methods of ex vivo activation continue to be controversial. A number of potential effector cells, including natural killer cells, monocytes/macrophages, cytolytic T cells and helper T cells, are exploitable and are the focus of clinical trials. A number of methods of activating these cells, including the use of recombinant cytokines, tumor cells, monoclonal antibodies, and gene insertion, have been developed. Varying specificities, trafficking and lytic potentials have been observed. In addition, the logistics of activating and expanding the various effectors ex vivo vary considerably. Although the optimal methods of identifying and activating cells have not been established, adoptive therapy with immunologically active cells can effect clinically significant responses in selected patients. Efforts to build upon the initial preclinical and clinical observations are in progress.