Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine) is a targeted therapy approved by the U.S. Food and Drug Administration (FDA) to treat:
HER2-positive metastatic breast cancer that has previously been treated with Herceptin (chemical name: trastuzumab) and taxane chemotherapy
early-stage HER2-positive breast cancer after surgery if residual disease was found after neoadjuvant (before surgery) treatment with Herceptin and 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.
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 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 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.
Kadcyla also can work after surgery in people diagnosed with early-stage HER2-positive breast cancer that was treated with Herceptin and taxane chemotherapy before surgery and had residual disease found during surgery.
Doctors call treatments given after surgery adjuvant treatments. Doctors call treatments given before surgery neoadjuvant treatments.
One way doctors judge the effectiveness of neoadjuvant chemotherapy is to look at the tissue removed during surgery to see if any actively growing cancer cells are present. If no active cancer cells are present, doctors call it a “pathologic complete response” or pCR. If there are cancer cells present in the tissue removed, this cancer is called “residual disease.”
There are several tests 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 figure out if the cancer was likely to respond. Two of the most common tests are:
The IHC test uses a chemical dye to stain the HER2 proteins. The IHC gives a score of 0 to 3+ that measures the amount of HER2 proteins on the surface of cells in a breast cancer tissue sample. If the score is 0 to 1+, it’s considered HER2-negative. If the score is 2+, it's considered borderline. A score of 3+ is considered 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.
The FISH test uses special labels that are attached to the HER2 proteins. The special labels have chemicals added to them so they change color and glow in the dark when they attach to the HER2 proteins. 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. With the FISH test, you get a score of either positive or negative (some hospitals call a negative test result “zero”).
Learn more about HER2 status.
What to expect when taking Kadcyla
Kadcyla is given intravenously, which means the medicine is delivered directly into your bloodstream through an IV or port. Kadcyla usually is given every 3 weeks in a doctor’s office.
People diagnosed with metastatic disease get Kadcyla every 3 weeks unless the cancer grows or unacceptable side effects develop.
People diagnosed with early-stage disease get Kadcyla every 3 weeks for a total of 14 cycles.
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 1-888-249-4918.
Kadcyla side effects
The most common side effects of Kadcyla are:
pain in bones, joints, and muscles
low blood platelet 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.
Liver problems: Kadcyla may cause severe liver problems, including liver failure. Symptoms include swelling or pain in the abdomen; a yellow tint in the eyes or skin (jaundice); swollen legs, feet, or ankles.
Kadcyla (T-DM1) prescribing information. Genentech. San Francisco, CA. 2019. Available at https://www.gene.com/download/pdf/kadcyla_prescribing.pdf (PDF).
— Last updated on April 7, 2022, 1:32 PM