Today, there are multiple approaches to immunotherapy for cancer, but they basically fall into two broad categories:
- Agents that boost the immune response. This approach uses a drug or agent that stimulates the immune system. The idea behind this is that a generalized, “revved up” immune response will be more effective in fighting the cancer.
- Agents that enable the immune system to recognize and fight the tumor. The newest approach to immunotherapy for cancer is based on new, emerging knowledge of the ways in which the immune system interacts with cancer cells.
Enabling the Immune Response
Checkpoint Inhibitors or Blockade Therapy
Your immune system has safeguards in place to prevent it from attacking healthy cells. Every time your immune system is stimulated, there are complex signals that stop immune cells from attacking and destroying your own normal tissue. These signals are called checkpoints. They slow down or stop an immune attack when healthy tissue is threatened. Cancer cells can use these checkpoints to hide from the immune response. Some cancers have learned how to activate checkpoints to avoid being killed by the immune system.
New drugs called checkpoint inhibitors aim to deactivate the checkpoint, helping your body fight cancer. Most patients who receive immunotherapy are on checkpoint inhibitors. Other types of immunotherapy drugs can be used to treat cancer, but they are not as common. Three checkpoints are being targeted: PD-1, PD-L1 and CTLA-4 proteins. Drugs that target them are now approved in certain situations, but there is still a lot to learn.
CTLA-4 Checkpoint Inhibitor
- Ipilumumab (Yervoy®) is a CTLA-4 checkpoint inhibitor approved to treat melanoma.
PD-1 and PD-L1 Checkpoing Inhibitors
- Nivolumab (Opdivo®),
- Atezolizumab (Tecentriq®),
- Pembrolizumab (Keytruda®) and
- Avelumab (Bavencio®).
These have been shown to successfully treat several types of advanced cancers.
Currently, checkpoint inhibitors only work for up to a third of patients who try them. Research is also being done to try checkpoint inhibitors in combination with other therapies, such as chemotherapy and other immunotherapy drugs.
- Block the ability of cancer cells to use checkpoints to hide from the immune system.
- Reactivate T cells that can fight the tumor
- Are called PD-1, PD-L1 and CTLA-4 inhibitors, because they target these checkpoints.
- Have been shown to successfully treat a growing number of advanced cancers such as melanomas, non-squamous cell lung cancers, kidney, and bladder cancers.
- Some tumors have biomarkers associated with levels of microsatellite instability (MSI-H). Therapies for this specific biomarker can be used to treat tumors of any type.
Adoptive (or CAR) T Cell therapies
Adoptive T Cell therapies use T cells collected from your blood. The T cells are modified in a lab to add special receptors (CARs) on their surface that allow the T cells to better find and kill cancer cells. CAR T cells have shown good results in clinical trials for leukemia and lymphoma. This kind of treatment is only available in clinical trials at a few major cancer centers.
See our CAR T Immunotherapy booklet for more information.
Boosting the Immune System
Cytokines have been used for years. They work by speeding up the growth of T cells and activating other immune cells. Interleukins and interferon are examples of cytokines that have shown some success in treating cancer. High dose interleukin 2 (IL2) leads to great responses in a small percentage of people with advanced melanomas and kidney cancers.
Treatment vaccines cause an active immune response against the cancer. There are many clinical trials that are studying therapeutic vaccines.
Currently, there is only one approved cancer vaccine, sipuleucel-T (Provenge®), which treats advanced prostate cancer. Provenge is made from the patient’s own white blood cells. These cells are sent to a lab where their ability to recognize and fight prostate cancer cells is boosted and then re-infused into the patient.
Researchers are also studying possible vaccines for other cancers like blood cancers and breast cancer.