What Is Targeted Therapy?

Targeted therapy is designed specifically to block proteins or receptors(REE-SEP-TORS) — A protein in or on a cell that may control some functions of the cell that drive cancer growth. All cells have proteins, but the protein receptors that targeted therapy attacks are ideally only present in a few types of normal cells. Thus, we can attack the cancer without damaging most normal cells. This means better, more specific treatment with fewer side effects.

When doctors know what part of the cancer cells to attack, targeted therapy can work very well at stopping the cancer from growing. However, it does not always work against every cancer, even if they have the same proteins. Let’s hop into your car so you can understand why this is the case.

A car with a hybrid engine can run on both gasoline and electricity. Some cancer cells are like this, too. More than one type of fuel can power them. If the treatment blocks only the electric engine, the gasoline engine can still run. Alternatively, if the treatment blocks the gasoline, the car will run off electricity.

Similarly, in cancer cells, a medication may block one protein(PRO-TEEN) — A naturally occurring, large, complex substance made up of amino acids that is an essential part of living organisms in a cell, but if a different mechanism powers the cell, this block may not work to stop the cancer, or it only helps for a short time (becoming resistant to the treatment). Today, doctors combine several medications to try to stop multiple mechanisms at the same time.

What Do They Target?

The most common non-hormonal target for breast cancer is the HER2/neu receptor(HER-TOO-NEW REE-SEP-TOR) — A protein involved in normal cell growth that can also make some breast cancers grow. Herceptin(HER-SEP-TIN) — A targeted therapy medication that attaches to HER2/neu receptors and blocks their function; brand name for trastuzumab® (trastuzumab(TRAZ-TWO-ZA-MAB) — A targeted therapy medication that attaches to HER2/neu receptors and blocks their function; generic name for Herceptin®) was the first HER2/neu-targeted medication for breast cancer and still is the most commonly used medication to block this specific receptor. Perjeta(PURR-JET-A) — A targeted therapy medication that attaches to HER2/neu receptors and blocks their function; brand name for pertuzumab® (pertuzumab(PURR-TWO-ZA-MAB) — A targeted therapy medication that attaches to HER2/neu receptors and blocks their function; generic name for Perjeta®) also attacks HER2/neu and is frequently combined with trastuzumab and chemotherapy(KEY-MOW-THAIR-AH-PEE) — Medication used to treat cancer before or after surgery(SIR-JER-REE) — Physical removal of a tumor.^1,2 Trastuzumab and pertuzumab are not the only HER2/neu-directed medications available, they are just two of the most common.

Since the approval of Herceptin, other medications have been discovered that target HER2/neu and many other proteins and receptors in a cancer. For example, PARP (polyadenosine diphosphate-ribose polymerase)An enzyme that helps regulate and repair DNA to allow a cell to function normally is a target for patients with BRCA gene mutations(BRAK-AH JEAN MU-TAY-SHUNS) — An abnormal or mutated breast cancer gene that is passed down from parent to child and is associated with an increased chance of developing breast cancer and other cancers. PARP-targeted medications interfere with BRCA1(BRAK-AH-ONE) — An abnormal or mutated breast cancer gene that is passed down from parent to child and is associated with an increased chance of developing breast cancer and other cancers; Breast Cancer Gene One and BRCA2(BRAK-AH-TOO) — An abnormal or mutated breast cancer gene that is passed down from parent to child and is associated with an increased chance of developing breast cancer and other cancers; Breast Cancer Gene Two cells' ability to repair themselves, leading to death.

Additionally, CDK4 & CDK6 (cyclin-dependent kinase)(C-D-K-FOUR AND C-D-K-SIX) — Enzymes that regulate the part of the cell cycle when cells prepare to duplicate and divide and mTOR (mechanistic target of rapamycin(MEH-CAH-NEH-STIK TAR-GET OF RAP-AH-MY-SIN) — Proteins that regulate cell growth and duplication) are new targets used for breast cancer patients. However, they are a little different than the medications that target HER2/neu and BRCA gene mutations. CDK4 & CDK6 and mTOR markers are actually in all cells (both normal and cancerous), but the medications target a specific part a cell. They attempt to inhibit cancerous cells from reproducing and multiplying.

Why Might It Be Recommended?

Targeted therapy is almost always recommended for HER2/neu positive patients. It is also considered for those with BRCA gene mutations.There are no specific cancer markers for CDK4 & CDK6 and mTOR, but you can talk to your doctor to see if these might be a good idea for you.

How Is It Given?

Depending on the medication, it will be administered orally (a pill) or through an IV infusion(I-V IN-FEW-SHUN) — Medication injected into the vein; intravenous. Targeted therapy can also be used in combination with one another, hormonal therapy(HORE-MOAN-OL THAIR-AH-PEE) — Anticancer medication used to target estrogen and progesterone receptors, or chemotherapy. How long you will be recommended to receive a targeted therapy depends on the medication and where you are in the patient journey.