Cancer and Immunotherapy
A Background on Immunotherapy’s Potential in Defeating Cancer
Cancer Immunotherapies are a New Method of Cancer Treatment
Among the more established treatment options, such as surgery, chemotherapy, targeted therapy, and radiation therapy, cancer immunotherapy is a rapidly emerging and important field. It has led to new clinical research studies and has garnered the attention of biotechnology and pharmaceutical companies, regulatory agencies, payors and hospital systems, cancer patients and their families, as well as the general public at large.
Cancer Immunotherapies Stimulate the Body’s Natural Immune System to Selectively Fight Cancer Cells and/or Prevent Cancerous Tumors
An essential characteristic of the immune system — a network of tissues, cells, and signaling molecules that work to protect the body — is its ability to differentiate foreign threats, including tumor cells, from normal cells. Though tumor cells, whether malignant or non-malignant, originate from normal cells, tumor cells can be recognized as foreign threats because of their selective elicitation of tumor antigens. These antigens may be released in the interstitial tissues and eventually in the bloodstream, or they may remain on the surface of tumor cells. The HER2/neu protein is one of the most widely expressed tumor antigens in multiple malignant tumors (“cancers”).
Several Cell Types Play an Important Role in the Development and Maintenance of Immune Responses Against Cancer
The most important immune cell types are antigen-presenting cells (“APCs”) and lymphocytes. APCs include various subtypes, such as dendritic cells, monocytes and macrophages, while lymphocytes include T cells. Once a patient is exposed to a tumor antigen (either by the presence of cancer itself or through active immunization through a cancer immunotherapy), the tumor antigen gets recognized by the APC and becomes “processed” through digestion into smaller fragments within the APC. Subsequently, the APC “communicates” with an inactive T-cell. Inactive T-cells search for tumor antigens by transiently binding to antigens presented by major histocompatibility complexes (“MHCs”) on the APCs. There is great variability in the expression of different subtypes of MHCs in the human population. The MHC system expresses human leukocyte antigens (“HLAs”) and these HLA subtypes determine the vigor and duration of any given T-cell response to a cancer among different patients.