Immunotherapies are cancer treatments that use the immune system to attack and remove cancer cells. Immunotherapies may be given in combination with another cancer treatment or used alone. Some immunotherapies are also targeted therapies, because they use antibodies to target abnormal proteins or receptors that are found in high quantities in cancer cells or the surrounding tissue.
Types of Immunotherapy
Several types of cancer immunotherapies are used to treat cancer, including:
Immunotherapy selection may depend on the following:
- Cancer type: Various immunotherapies are approved for use in different types of cancer. You can learn more about immunotherapy by cancer type in our Cancer Treatment by Cancer Type section.
- Cancer stage, subtype and grade: Some immunotherapies are approved only for use in certain stages of cancer, grades or types of cancer.
- Location or site of cancer that has spread: Certain immunotherapies may work better in different organs. For example, the blood-brain barrier protects your brain by filtering out drugs. If cancer has spread to your brain, your oncologist may treat you with a therapy that is able to cross the blood-brain barrier.
- Number of prior treatments and response: Some immunotherapies are used to treat progression or recurrence after a specified number or type of prior treatments have already been used.
- Results of tumor biomarker testing: Some immunotherapies work best on cancers that express certain biomarkers. Biomarkers can be proteins, genes changes, and other cell products. You can learn more about biomarker testing for selecting immunotherapies in our Common Biomarkers sections.
- Results of genetic testing for an inherited mutation: Some immunotherapies are effective for treating cancers in people with certain inherited mutations. Immune checkpoint inhibitors, for example, may be effective for treating cancers in people with mutations associated with Lynch syndrome.
Each immunotherapy drug has different indications. You can read more in our section on Indications. Like all cancer treatments, immunotherapies can have side effects. Visit our Side Effects section for more information.
Our immune system can tell the difference between normal cells and those that are foreign (such as bacteria) or abnormal (such as cancer cells). This allows our immune system to fight cancer and infections while sparing normal cells.
The immune system uses a "checkpoint" system to help immune cells recognize normal cells. Like a lock and key, when proteins on the immune cells bind to proteins on normal cells, it deactivates the immune cells and prevents them from attacking. Cancer cells can sometimes produce their own checkpoint proteins, which can switch the immune cells off.
Immune checkpoint inhibitors are drugs that prevent cancer cells from switching off immune cells. This allows the immune system to find, unmask and destroy cancer cells.
Immune checkpoint inhibitors have received FDA approval to treat a number of different types of cancers. Examples of immune checkpoint inhibitors include:
- Keytruda (pembrolizumab)
- Tecentriq (atezolizumab)
- Opdivo (nivolumab)
- Imfinzi (durvalumab)
- Yervoy (ipilumumab)
Immune checkpoint inhibitors may work well on cancers that have a defect in genes responsible for a type of DNA damage known as DNA mismatch repair. "Mismatch repair" (MMR) genes repair DNA damage that occurs during cell division. Tumors with mutations in mismatch repair genes are called "MMR-Deficient" (MMR-D). MMR-D tumors have a cellular abnormality known as Microsatellite Instability or MSI-High. Mutations in the following genes are associated with MMR-D tumors:
Testing tumors for MMR-D or MSI-High can be important, because these tumors are more likely to respond to a type of immunotherapy known as immune checkpoint inhibitors.
in a type of DNA repair that causes the cancer to have a genetic feature called “microsatellite instability-high (MSI-H).” MSI-H cancers are associated with Lynch syndrome, an inherited syndrome associated with colorectal, uterine and ovarian cancers.
Monoclonal antibodies may be considered both immunotherapy and targeted therapy. While they act like antibodies that your immune system naturally produces, they are also designed to target specific proteins or receptors found on cancer cells. Avastin (bevacizumab) is an example of an antibody that kills cancer cells by blocking VEGF, a protein that tumors use to make new blood supply. Herceptin (trastuzumab)—and similar anti-Her2 therapies—are monoclonal antibody that works against the HER2 protein, which is found in large amounts on some types of breast cancer cells.
Sometimes monoclonal antibodies are attached to additional cancer-fighting drugs, such as chemotherapy. The monoclonal antibody helps deliver the chemotherapy to the targeted cancer cells. Like Herceptin, Kadcyla, (also called TDM-1) targets the HER2 protein. However, it has a chemotherapy drug called DM1 attached. It is used to treat HER2-positive breast cancer. These combination antibody-chemotherapy medications are also called "antibody-drug conjugates" (ADC).
Non-specific immunotherapies broadly boost the immune system. Even though they do not target cancer cells specifically, they can still create a better overall immune response against cancer cells.
Examples of non-specific immunotherapies are interleukins that stimulate immune system cells to grow and divide more quickly, and interferons that boost the ability of immune cells to attack cancer cells. Both drugs may be used to treat melanoma.
Cancer treatment vaccines are molecules that are introduced into the body to start an immune response against cancer cells; they are different from vaccines that work as prevention against viruses such as Human Papilloma Virus (HPV). Instead of preventing disease, cancer treatment vaccines encourage the immune system to attack an existing disease. These vaccines are sometimes made from a patient’s own tumor cells. One example is Provenge (sipuleucel-T), a cancer treatment vaccine that is used to treat some men with metastatic prostate cancer. Other cancer treatment vaccines are being tested in clinical trials to treat a range of cancers.
Other cancer vaccines may be made by altering viruses to attack cancer cells. Imlygic (talimogene laherparepvec or T-VEC therapy) is a genetically-altered virus that is used to treat advanced melanoma.