Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine) is a targeted therapy approved by the U.S. Food and Drug Administration to treat HER2-positive metastatic breast cancer that has previously been treated with Herceptin (chemical name: trastuzumab) and a taxane chemotherapy.
Kadcyla is a combination of Herceptin and the chemotherapy medicine emtansine. Doctors call Kadcyla an antibody-drug conjugate targeted therapy. The emtansine is attached (conjugated) to the Herceptin.
Learn more about:
- How Kadcyla works
- Is Kadcyla right for you?
- What to expect when taking Kadcyla
- Paying for Kadcyla
- Kadcyla side effects
How Kadcyla works
Some breast cancer cells make (overexpress) too many copies of a particular gene known as HER2. The HER2 gene makes a protein known as a HER2 receptor. HER2 receptors are like ears, or antennae, on the surface of all cells. These HER2 receptors receive signals that stimulate the cell to grow and multiply. But breast cancer cells with too many HER2 receptors can pick up too many growth signals and so start growing and multiplying too much and too fast. Breast cancer cells that overexpress the HER2 gene are said to be HER2-positive. About one out of every four breast cancers is HER2-positive.
Herceptin is approved by the U.S. Food and Drug Administration (FDA) to treat advanced stage, HER2-positive breast cancers and to lower the risk of recurrence of early-stage, HER2-positive breast cancer with a high risk of recurrence. Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals.
Emtansine, like some other chemotherapy medicines, disrupts the way cells grow. Emtansine isn’t a targeted medicine, which means it can affect healthy cells as well as cancer cells. Emtansine is never given alone to treat any type of cancer because it is too toxic.
Kadcyla was designed to deliver emtansine to cancer cells in a targeted way by attaching emtansine to Herceptin. Herceptin then carries emtansine to the HER2-positive cancer cells. This way, the emtansine is less toxic to healthy cells and more effective in treating cancer cells.
Is Kadcyla right for you?
Kadcyla can work in people diagnosed with HER2-positive metastatic breast cancer that has previously been treated with Herceptin and a taxane chemotherapy.
Metastatic breast cancer is breast cancer that has spread to other parts of the body away from the breast, such as the bones or liver.
Four tests can be used to find out if breast cancer is HER2-positive. To have been previously treated with Herceptin, one or more of these tests was used to determine whether or not the cancer was likely respond:
IHC is the most commonly used test to see if a tumor has too much of the HER2 receptor protein on the surface of the cancer cells.
The IHC test gives a score of 0 to 3+ that measures the amount of HER2 receptor protein on the surface of cells in a breast cancer tissue sample. If the score is 0 to 1+, it’s called “HER2 negative.” If the score is 2+, it's called "borderline." A score of 3+ is called “HER2 positive.”
If the IHC test results are borderline, it’s likely that a FISH test will be done on a sample of the cancer tissue to determine if the cancer is HER2-positive.
FISH (Fluorescence In Situ Hybridization)
The FISH test also looks to see if the cancer is HER2-positive. This test is the most accurate, but it is more expensive and takes longer to return results. This is why an IHC test is usually the first test done to see if a cancer is HER2-positive. The FISH test shows how many copies of the HER2 gene are in tumor cells. The more copies of the gene, the more HER2 receptors the cells have.
With the FISH test, you get a score of either "positive" or "negative" (some hospitals call a negative test "zero"). If the cancer is FISH positive, it will probably respond well to Kadcyla.
SPoT-Light HER2 CISH (Subtraction Probe Technology Chromogenic In Situ Hybridization)
The SpoT-Light HER2 CISH test looks for how many copies of the HER2 gene are in the tumor cells of a breast cancer tissue sample. The SPoT-Light test is less complicated than the FISH or IHC tests.
With the SPoT-Light test, you get a score of either "positive" or "negative." If the cancer is SPoT-Light HER2-positive, it will probably respond well to Kadcyla.
Inform HER2 Dual ISH (In Situ Hybridization)
The Inform HER2 Dual ISH test uses a special stain that makes HER2 proteins change color. The test can be used on tissue samples that have been stored in wax or other chemicals. The Inform HER2 Dual ISH test offers more precise results than the IHC HER2 test. It is also less expensive and doesn’t need the special microscope of the FISH HER2 test.
With the Inform HER2 Dual ISH test, you get a score of either “HER2 positive” or “HER2 negative.”
Learn more in Breast Cancer Tests.
What to expect when taking Kadcyla
Kadcyla is given intravenously, which means it’s delivered directly into your bloodstream through an IV or port. Kadcyla usually is given every 3 weeks in a doctor’s office. Most people get Kadcyla every 3 weeks unless the cancer grows or unacceptable side effects develop.
Women who are pregnant or planning to get pregnant should not be given Kadcyla. Kadcyla can cause embryo death and birth defects. It’s important that you don’t get pregnant while you’re getting Kadcyla; you must use effective birth control.
Visit Treatment for Breast Cancer During Pregnancy for more information.
Paying for Kadcyla
If your doctor prescribes Kadcyla and you have any problems getting it covered by insurance or don’t have insurance, you can get in touch with Genentech’s Access Solutions patient assistance program. Access Solutions can help investigate your insurance coverage benefits, appeal denied claims, and provide other assistance. You also can call Access Solutions at 1-866-422-2377.
Kadcyla side effects
The most common side effects of Kadcyla are:
- bone and joint pain
- muscle pain
- low blood platelet count
- liver problems
- nerve damage
- low red blood cell count
- low potassium levels
Kadcyla also can cause other serious side effects. While these serious side effects are rare (about 1-2% of people treated with Kadcyla will experience them), it’s important to know about them:
- Heart problems: Kadcyla may cause serious heart problems, including some that don’t have symptoms, such as reduced heart function, and some that do have symptoms, such as congestive heart failure. Symptoms to watch for include swelling of the ankles or legs, shortness of breath, cough, or weight gain of more than 5 pounds in less than 24 hours.
- Lung problems: Kadcyla may cause inflammation of the lungs, which can be life-threatening. Symptoms include trouble breathing, cough, tiredness, and fluid in the lungs.
- Kadcyla (T-DM1) prescribing information. Genentech. San Francisco, CA. 2018. Available at https://www.gene.com/download/pdf/kadcyla_prescribing.pdf.