Therapeutic cancer vaccines: using unique antigens.

A decade ago, it seemed rational that our rapidly increasing knowledge of the molecular identities of tumor antigens and a deeper understanding of basic immunology would point the way to an effective therapeutic cancer vaccine. Significant progress has been made, but we do not yet have a cancer vaccine that can reliably and consistently induce tumor destruction or improve patient survival. Random mutations in cancer cells generate unique antigens in each individual, and this may be important in terms of generating a therapeutic immune response. Autologous heat shock protein-peptide complexes produced from each patient's tumor is a logical personalized approach that may obviate the need to identify the unique antigens contained in the individual vaccine. Heat shock proteins elicit adaptive and innate immune responses and have been tested in a variety of animal models and different human cancers. Activity has been seen in several animal studies. Early-phase human studies have also suggested some activity in certain cancers. Large, randomized phase 3 studies are ongoing, and these will effectively answer the question of efficacy regarding this approach to therapeutic vaccination. There are sufficient data to support the notion that cancer vaccines can induce anti-tumor immune responses in humans with cancer. How best to translate this increase in immune responsiveness to consistently and reproducibly induce objective cancer regression or increased survival remains unclear at this time.