Colorectal Tumor Immunity

There have been many successes for immunotherapy, including BCG for treatment of bladder cancer, recombinant cytokine/tumor infiltrating lymphocyte (TIL) therapy and the use of monoclonal antibodies such as Herceptin, that target growth factor receptors and induce apoptosis. However, more recent studies have led to a better understanding of the molecular basis for immune recognition of cancer. Many tumor antigens have been identified and numerous vaccination approaches have been tested in the clinic leading to new insights into the complexity of tumor immunity. Although vaccination results in stimulation of T cell responses, this appears to be rarely associated with tumor regression. This relative lack of response may be due to only partial activation of T cells which proliferate but do not acquire full effector function as well as to the tumor environment which is hostile to the incoming T cell infiltrate. The challenge for the future will be to fully activate anti-tumor immunity whilst combating the profoundly tolerogenic tumor environment.