Targeted Therapies for Hormone-Positive Breast Cancer
If a cancer grows in response to the hormones estrogen
and progesterone, it is hormone receptor-positive. These cancers are often treated with hormonal therapy medicines. Hormonal therapy medicines stop the body from making estrogen or block the effects of estrogen that drives the growth of hormone-sensitive cancer cells.
Over time, some breast cancers build resistance to hormonal therapies. Your doctor may then need to give you a different medicine. Recent studies have shown that combining certain hormonal therapies with certain targeted therapies can make the hormonal therapies more effective.
There are several kinds of targeted therapy that have been approved by the FDA to treat hormone receptor-positive breast cancer. These medicines are currently only used to treat metastatic breast cancer, but these and other targeted therapies are being studied to
- understand how well they work
- explore their use in other situations
- learn more about the traits that cause certain cancers grow
If you have hormone receptor-positive breast cancer and are interested in targeted therapies, ask your doctor whether you’re able to participate in a clinical trial.
In this section, you’ll learn more about the classes of targeted therapies used to treat hormone receptor-positive breast cancer and the medicines within each type.
Targeted therapies often have fewer side effects than chemotherapy, but like all medicines, they may still cause them. The side effects of each medicine depend on what part of the cancer cell the medicine targets. Medicines that target features that are also in healthy cells can cause more side effects. Side effects can be different depending on how your body responds to certain medicines.
Your doctor, pharmacist or nurse can help you manage any side effects. You can also go to our section on Side Effects for more information.
mTOR Inhibitors
mTOR, or mammalian target of rapamycin, is a type of protein called a kinase. Kinase helps control cell growth.
In some cancers, mTOR-activated proteins work abnormally and encourage cancer cells to grow and spread. mTOR also directs nutrients to the cancer cells, helping to support them.
mTOR inhibitors are a newer type of cancer growth blocker that works to slow or stop mTOR’s role in the growth of cancer cells. The mTOR inhibitor approved to treat metastatic breast cancer is:
CDK 4/6 Inhibitors
CDK 4/6 inhibitors, also called cyclin-dependent kinase 4/6 inhibitors, target two specific kinases, CDK 4 and 6. These kinases, or proteins, signal cancer cells to grow and divide. This type of medicine slows the growth or spread of cancer cells. The CDK 4/6 inhibitors approved to treat metastatic breast cancer are: