Until the late 1990s, almost all drugs used to treat cancer worked by killing cells in the DNA replication and cell division processes. While these drugs mostly killed cancer cells, they also killed some normal cells. As researchers continued to learn more about DNA changes and cancer-triggering proteins, they discovered a specific type of treatment that only targets these proteins without killing the normal cells—targeted therapy.
Types of targeted therapy
Since there are many types of cancer and gene changes that drive the growth of the cells associated with cancer, targeted therapy for a specific type of cancer may not be the same for another. Even for people with the same general type of cancer, a person’s specific type of colon cancer may differ from others because of their varying gene changes. Moreover, researchers discovered that the environment in which cancers develop and thrive is not always the same.
These details allowed them to develop different types of targeted therapy. The two most common are:
- monoclonal antibodies – They block a specific target on the areas around the cancer cells or send toxic substances right to the cancer cells. They also help radiation and chemotherapies reach cancer cells better.
- small-molecule drugs – They inhibit the process that allows cancer cells to multiply and spread. One example of this is an angiogenesis inhibitor, which stops the formation of new blood vessels.
How targeted therapy works
To develop a target therapy treatment, experts first identify the mutated gene and target the proteins responsible for the mutation. This treatment affects the cancer cells they target in different ways:
- Blocks or turns off signals that drive the cancer cell’s growth
- Stops blood vessel production that feeds the cancer cells
- Triggers the immune system to kill the cancer cells
- Carries toxins to the cancer cells to kill them
The U.S. Food and Drug Administration has approved the use of targeted therapies for different types of cancers, either alone or in combination with other treatments like standard chemotherapy, surgery, or radiation therapy. If a patient’s treatment plan includes targeted therapy, knowing how it works and its limitations can help in making informed decisions.
Common side effects and limitations of targeted therapy
Targeted therapy may cause diarrhea and liver problems depending on the drug used. Others may also experience fatigue, mouth sores, high blood pressure, difficulty healing wounds or clot blood, and nail, hair, and skin problems. Very rarely, targeted therapy may cause holes in the digestive tract walls. However, medicines are available to treat or prevent these side effects, and they normally go away after the treatment ends.
Like other cancer treatments, targeted therapy may not work best for all patients. Cancer cells may become resistant to this therapy, drugs for some targets are hard to develop due to the complex target’s structure and function in the cell and the body’s response to the treatment may not last over time.
