Cancer immunotherapy using recombinant Listeria monocytogenes: transition from bench to clinic.

Cancer immunotherapy has developed into a field of intense study as aspects of the immune system involved in the eradication of cancer have become delineated. Listeria monocytogenes is a gram-positive, facultative intracellular bacterium which infects antigen presenting cells (APC), and is being used as a cancer vaccine to deliver tumor antigens directly to the APC. This results in the generation of a strong immune response towards the tumor associated antigen and direct targeting of the tumor by the immune system. Advances in this field have led to the development of a series of L. monocytogenes-based cancer vaccines, which are currently in clinical trials. A phase I study has shown these vaccines can be safely administered and well-tolerated in terminal stage cancer patients and an efficacy signal was observed in patients who did not respond to other therapies. Additional data on the efficacy of these vaccines is expected in the near-term.