Immunotherapy

Abstract

The approval in April 2010 by the FDA in the USA of a prostate cancer vaccine (Sipuleucel-T, Provenge, Dendreon Inc.) may herald a new era in T-cell-directed cancer therapies. The magnitude of scientific effort to reach this point should not be underestimated. The key has been unraveling the complex mechanisms between the recognition of tumor antigen, breaking immune tolerance, and generation of a long-lasting and clinically meaningful cellular response. Therapeutic vaccines (i.e., vaccines for patients with ongoing disease) have two objectives: priming Ag-specific T cells and reprogramming memory T cells (i.e., a transformation from one type of immunity to another, for example, regulatory to cytotoxic). Numerous therapeutic approaches have been tested in prostate cancer patients, including autologous and allogeneic tumor cells modified to express various cytokines, peptides, proteins, and DNA vaccines. The evolution of cellular vaccines includes addressing the local immunosuppressive tumor microenvironment, modulating immune response through checkpoint blockade and, importantly, combining cellular immunotherapy with other treatment modalities such as chemotherapy exploiting their intrinsic immunomodulatory properties.