What is targeted therapy?
Targeted therapy is a type of cancer treatment that attacks specific molecular targets in cancer cells that are involved in the growth, progression, and spread of cancer. By utilising drugs or other substances, targeted therapy blocks the growth of cancer cells and induces the death of the cancer cells by destroying those targets. Targeted therapies for cancer are also known as "molecularly targeted drugs," "molecularly targeted therapies" or "precision medicines”.
Targeted therapies differ from other cancer treatments because:
- They act on specific molecular targets that are associated with cancer
- They are designed to interact with their target only
- They not only destroy cancer cells but block their growth
Understanding targeted therapy
To understand how targeted therapies work, it helps to understand how cells work. Cells make up every tissue in your body. There are many different cell types, each with its own function in the body. When the cells begin to change, it is called a mutation and is what is known as the start of cancer. A person's genes tell the cells how to make proteins that will keep the cell working. While the cells normally divide and die, cancer cells are abnormal and divide and mutate more rapidly, and do not die. When cells divide abnormally or live too long, the cells grow out of control and form a tumour.
While targeted therapy is a cancer treatment that uses drugs, it differs from other cancer treatments that use drugs because it works by targeting cancer's specific genes, proteins, or the tissue environment to stop the growth and survival of the cancer cells.
Most types of targeted therapy help treat cancer by interfering with specific proteins that help tumours grow and spread throughout the body. Targeted therapies help prevent the growth and spread of cancer cells in the following ways:
- Helping the immune system destroy cancer cells by making cancer cells easier to identify
- Stopping the growth of the cancer cells by interfering with them by preventing the proteins from being produced.
- Stopping the spread of cancer cells by preventing signals that help form blood vessels that feed cancer cells.
- Deliver cell-killing substances to cancer cells.
- Cause cancer cell death.
- Starve cancer of the hormones it needs to grow with hormone therapy.
Targeted cancer therapies are the future of anti-cancer treatment research and are the cornerstone of precision medicine, which uses a person's genes and proteins to prevent, diagnose, and treat disease. Many targeted cancer therapies have been approved by the FDA, while others are still being studied in clinical trials.
How are targeted therapies administered?
Studies show that not all tumours have the same targets. So the same targeted treatment will not work for everyone. Targeted therapies are therefore very much tailored to the individual patient depending on the type of cancer, gene profile and stage of cancer. Your doctor might order tests to learn about the genes, proteins, and other factors in your tumour to help decide which targeted therapy would be most effective for your cancer treatment.
There are different types of targeted therapies which can be classified as monoclonal antibodies or small-molecule drugs.
Monoclonal antibodies block a specific target on the outside of cancer cells or in the area around the cancer. Monoclonal antibodies can also send toxic substances directly to cancer cells which can aid chemotherapy and radiation therapy get to cancer cells better. Monoclonal antibodies are generally administered intravenously (IV).
Small-molecule drugs, on the other hand, block the process that helps cancer cells multiply and spread. Small-molecule drugs are taken as tablets.
- Angiogenesis inhibitors are an example of this type of targeted therapy. New blood vessels form naturally in tumours, because they grow rapidly, and require new blood vessels for nutrition and oxygen. These types of drugs starve the tumour by keeping new blood vessels from forming.
- Epidermal growth factor receptor (EGFR) inhibitors are another example which binds to the EGFR protein found on the surface of some cells that causes cells to divide, slowing down or stopping cell growth.
- Tyrosine kinase inhibitors (TKIs) is a type of small-molecule drug that identifies and inhibits tyrosine kinases, the enzymes responsible for the activation of many proteins in cells. Tyrosine kinase inhibitors stop the epidermal growth factor receptor (EGFR). This targeted therapy attacks specific types of cancer cells while causing less damage to normal cells.
You may have treatment every day, every week, or every month. Some targeted therapies are given in cycles. A cycle is a period of treatment followed by a period of rest. The rest period gives your body a chance to recover and build new healthy cells.
Side effects of targeted therapy
Since targeted therapies are more dependence on the targets than are normal cells, these cancer therapies are less toxic than traditional chemotherapy drugs. Nonetheless, there are side-effects. The aim of the following information is to give you clear expectations of the complications of these treatments.
The most common side effects seen with targeted therapies are:
If you have 3-4 loose stools a day, you should consult your general practitioner or oncologist immediately. Be sure to drink clear fluids (soup, soft drinks, tea and ± two litres of water per day).
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