These are specifically designed antibodies in the lab that can attack a specific antigen found in cancer cells. The US FDA has approved more than a dozen Monoclonal Antibodies to treat specific cancers. They work by either boosting the person’s immune response to cancer cells or may block the antigens in cancer cells and prevent its proliferation.
A person’s immune system fights the foreign cells, which are different from the normal cells through specific “checkpoints”. Checkpoints are nothing but molecules on specific immune cells that are required to be activated or deactivated to start an immune response.
Checkpoint inhibitors are drugs that target these checkpoints and are showing promising results in treating melanoma, non-small cell lung cancer, Hodgkin Lymphoma and cancer of bladder, kidney, head and neck. Notable checkpoint inhibitor drugs are Pembrolizumab (Keytruda), Nivolumab (Opdivo), Atezolizumab (Tecentriq), Avelumab (Bavencio), Durvalumab (Imfinzi), Ipilimumab (Yervoy) etc.
Cancer vaccines are meant both for prevention and treatment. The vaccines for treatment are different from those used for prevention. Vaccines to prevent HPV (Human Papilloma Virus) and HBV infections are well known. Cancer treatment vaccines facilitate the immune system to attack the already existing cancer cells.
These vaccines are generally made from cancer cells, parts of cells or pure antigens. The patient’s immune cells may also be used at times to create the vaccine. Sipuleucel- T (Provenge) is the only cancer treatment vaccine approved in the US for treating advanced prostate cancer.
CAR (Chimeric Antigen Receptor) T- Cell Therapy
The T-Cells, a type of white blood cells are removed from the patient’s body and tweaked in a lab to fight the cancer cells. These specially engineered cells are then infused back into the patient’s body. Currently, two CAR-T cell Therapies are approved by FDA – one for lymphoblastic leukemia and the other for specific types of large B-Cell Lymphoma (also one of the types of non-Hodgkin’s Lymphoma).
Non-specific cancer immunotherapies and adjuvants:
The adjuvants do not directly attack the cancer cells but stimulate the body immunity system to generate better immune response against the cancer cells. This is done by injecting cytokines (chemicals produced by some immune cells essential to maintain vitality of other immune cells) into the patient’s body. Sometimes these are combined with specific chemotherapy drugs but the side effects are more pronounced in combination therapy. These can be applied in treating certain types of Lymphoma, Leukemia, Melanoma and cancer of kidney.
Although cancer immunotherapy is still at the nascent stage, the success achieved so far assure an enhanced standard of care for patients with advanced stage of cancer extending their longevity.