Targeted Therapy 101: A Primer
July 17, 2017 | by City of Hope
These fine-tuned treatments target cancer cells more specifically than traditional chemotherapy, explained George Hajjar, M.D., an oncologist in the Department of Medical Oncology & Therapeutics Research at City of Hope.
Here’s what you need to know about these promising new treatments.
What is targeted therapy?
Traditional chemotherapy is designed to kill cells that divide rapidly. That includes not only cancer cells, but also many healthy cells throughout the body. As a result, chemotherapy usually goes hand-in-hand with significant side effects such as nausea and hair loss.
Targeted therapies, on the other hand, are designed to target specific molecules that are unique to a certain type of tumor or cancer cell. Those molecules are essential for those cells to survive, grow and spread, Hajjar explained. Targeting those molecules can stop the tumor from growing.
“By identifying these molecules and then developing medications that specifically target them, we are working on blocking the function of these molecules, which are essential for the survival and growth of these tumors,” Hajjar said.
What targeted therapies are available?
A variety of targeted therapies have emerged so far, Hajjar said. Those treatments include:
- Hormonal therapies. Some diseases, such as breast cancer, depend on hormones to grow. “By suppressing the hormones, we can control them,” he said.
- Angiogenesis therapies. Tumors need a blood supply to grow, and they are capable of making their own blood vessels through a process called angiogenesis. “If we target that capability, the tumors will have not enough blood and they eventually suffocate and die,” he said.
- Apoptosis therapies. Apoptosis is the normal process of cell death. Cancer cells can grow and divide indefinitely, instead of dying when they should. These medications can program “death sentences” into the cells so they don’t keep growing, he said.
- Immunotherapy treatments. The body’s immune system fights off disease-causing organisms, but cancer cells can hide from the immune system. New immunotherapy treatments harness the body’s own immune system to recognize and attack cancerous cells.
- Monoclonal antibody therapy. Antibodies are proteins that circulate normally in the body, seeking out foreign substances like viruses or bacteria. Researchers are working to design monoclonal antibodies that will stick to cancer cells, delivering radioactive molecules or cell-killing toxins directly into the tumor. “We have one approved for prostate cancer, which was a breakthrough treatment for these patients,” Hajjar said.
Targeted treatments in practice
These days, it’s common to test patients’ tumors to look for certain genetic markers that are sometimes associated with that disease. Patients with lung cancer, for instance, can be tested for certain genes found in a small percentage of lung cancers.
While not all patients will have those genetic markers, those that do are likely to respond to a targeted therapy that can attack the tumor with minimal side effects.
Targeted treatments don’t tend to cause nausea and hair loss, as chemotherapy drugs tend to do. But they can have other side effects, ranging from skin rashes to more serious problems such as osteoporosis or thyroid disorders.
Despite side effects, these medications hold great promise, Hajjar said. Targeted therapies aren’t yet available for all types of cancer, but researchers at City of Hope and beyond are working to identify new targets and develop drugs to go after them.
“It's a very exciting time to be practicing oncology in this era of targeted therapy,” he said.
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