What is Immunotherapy?
Immunotherapy, also known as biologic therapy or immuno-oncology, is a type of cancer treatment that stimulates the body's immune system to recognize, target, and destroy cancer cells. Unlike traditional chemotherapy and radiation, which directly attack cancer cells, immunotherapy unleashes the body's natural defenses to combat cancer.
There are several types of immunotherapies, and each helps the immune system differently.
Types of immunotherapy
Immune checkpoint therapy helps cancer-fighting immune cells, called T cells, mount a longer-lasting response against the cancer.
Adoptive cellular therapy increases the number and/or effectiveness of immune cells, usually T cells, improving the immune response's power against cancer. There are four main types of adoptive cellular therapy:
Chimeric antigen receptor (CAR) T cell therapy involves modifying a patient's immune cells (T cells) to express a receptor targeting cancer cells. These engineered T cells are then infused back into the patient, where they recognize and eliminate cancer cells.
Chimeric antigen receptor (CAR) natural killer (NK) cell therapy is a promising new cellular immunotherapy in clinical trials. NK cells are immune system cells that identify and then kill abnormal cells, including some cancer cells. Many cancers are good at avoiding detection, though. This limits the ability of NK cells to fight the disease naturally. In CAR NK cell therapy, NK cells are engineered to better recognize cancer, boosting their ability to find and kill cancer cells. Researchers do this by collecting NK cells from donated umbilical cord blood. They then add a molecule known as a chimeric antigen receptor, or CAR, to the NK cells. This CAR recognizes a molecule on the surface of cancer cells, enabling the CAR NK cells to better find and fight cancer.
Tumor-infiltrating lymphocyte (TIL) therapy uses a patient's T cells that are collected from a piece of the surgically-removed tumor. While these cells may recognize the cancer, there are too few of them to succeed. These cells are increased substantially in the lab and then returned to the patient.
Endogenous T cell (ETC) therapy uses T cells from a patient's blood. From this diverse pool of T cells, doctors select only those that may recognize signatures specific to the cancer. These specific T cells are increased substantially and then returned to the patient.
Cancer vaccines help the body recognize cancer cells and stimulate the immune system to destroy them.
Cancer vaccines usually contain one of the following:
- cancer cells taken from the patient's tumor
- proteins designed to attach themselves to cancer cells
- proteins specific to a patient's tumor
Monoclonal antibodies are man-made versions of immune system proteins. mAbs can be very useful in treating cancer because they can be designed to attack a very specific part of a cancer cell.
Cytokine therapy relies on proteins called interferons and interleukins to trigger an immune response. Interleukin-2 (IL-2) is used to treat kidney cancers and melanomas that have spread to other regions of the body. Interferon alpha (IFN-alpha) is currently being used to treat melanoma, kidney cancer, and certain leukemias and lymphomas. These cytokine treatments are also being combined with other types of immunotherapies to increase their effectiveness.
Combining immunotherapies can be a powerful strategy in cancer treatment, either by using two different types together or by integrating immunotherapy with other therapies like chemotherapy. These combination approaches aim to enhance the overall effectiveness of treatment. While some immunotherapies have become standard treatments for specific cancers, there are still others that are available only through clinical trials.