Tumour-associated antigens: considerations for their use in tumour immunotherapy

Since their discovery, tumour-associated antigens (TAA) have provided highly inviting targets for cancer therapy, especially immunotherapy. Evidence now points to their involvement in the malignant phenotype of transformed cells and heightens their importance for being targeted by different treatments. TAA vary in their nature and pattern of expression and this influences the way therapy is directed towards them. While large numbers of these antigens have been isolated from solid tumours, fewer are linked with haematological malignancies. Those TAA found in this latter group of cancers, referred to as leukaemia-associated antigens (LAA), also appear to have significant potential for promoting the malignant phenotype and have been described in detail in terms of expression and therapy. Interestingly, the action of some of LAA in blood cancers, which are stem cell derived, could act as model for solid tumours, which are increasingly thought to be also derived from a cancer stem cell origin. In this review, TAA and their use in immunotherapy will be discussed. The nature and expression of these antigens will be described together with the events that provide tumours, including haematological cancers, with the ability to avoid immune deletion.