Final survival results from two studies, the EMILIA trial and the TH3RESA trial, show that Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine), a targeted therapy medicine:
- improved overall survival in people diagnosed with HER2-positive, advanced-stage breast cancer that had stopped responding to a standard targeted therapy regimen (EMILIA study)
- improved overall survival in people diagnosed with metastatic, HER2-positive breast cancer that had stopped responding to Herceptin (chemical name: trastuzumab) and Tykerb (chemical name: lapatinib) compared to the women’s doctors’ treatment of choice (TH3RESA study)
Both studies were published in the June 2017 issue of The Lancet Oncology. Read the abstracts of:
- "Trastuzumab emtansine versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer (EMILIA): a descriptive analysis of final overall survival results from a randomised, open-label, phase 3 trial"
- "Trastuzumab emtansine versus treatment of physician’s choice in patients with previously treated HER2-positive metastatic breast cancer (TH3RESA): final overall survival results from a randomised open-label phase 3 trial"
Overall survival is how long a person lives, with or without the cancer growing.
Advanced-stage breast cancer is breast cancer that has spread to tissue near the breast, such as the chest wall. Metastatic breast cancer is breast cancer that has spread to part of the body away from the breast, such as the bones or liver. Metastatic breast cancer is also considered advanced-stage disease.
Kadcyla is a combination of Herceptin and the chemotherapy medicine emtansine. In Kadcyla, the emtansine is attached to the Herceptin. In earlier studies on Kadcyla, it was reported that the chemotherapy medicine maytansine was attached to Herceptin to form Kadcyla. Emtansine is a derivative of maytansine.
Kadcyla is approved by the U.S. Food and Drug Administration to treat HER2-positive, metastatic breast cancer that has previously been treated with Herceptin and a taxane chemotherapy.
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. HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. 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.
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.
The EMILIA study
The EMILIA study looked at 991 men and women diagnosed with either metastatic or locally advanced, HER2-positive breast cancer that had stopped responding to a standard treatment regimen of Herceptin and a taxane chemotherapy. Taxol (chemical name: paclitaxel), Abraxane (chemical name: albumin-bound or nab-paclitaxel), and Taxotere (chemical name: docetaxel) are taxanes.
The participants were randomly assigned to receive one of two treatment regimens:
- half the people got a combination of the targeted therapy Tykerb and the chemotherapy Xeloda (chemical name: capecitabine); this combination already is FDA approved to treat advanced-stage, HER2-positive breast cancer that has stopped responding to Herceptin
- half the people got Kadcyla
Because early results from the study were promising, after about 2 years of follow-up, people in the Tykerb-Xeloda treatment group were allowed to cross over to the Kadcyla treatment group; 136 of 496 people crossed over.
Overall survival was longer in the people treated with Kadcyla:
- people treated with Kadcyla lived for 29.9 months
- people treated with Tykerb and Xeloda lived for 25.9 months
People treated with Kadcyla also had fewer severe side effects than people treated with Tykerb and Xeloda:
- 48% of people treated with Kadcyla had a severe side effect
- 60% of people treated with Tykerb and Xeloda had a severe side effect
The most common severe side effects in the Kadcyla treatment group were:
- low white blood cell count
- liver problems
- low red blood cell count
The most common severe side effects in the Tykerb-Xeloda treatment group were:
- hand-foot syndrome
The TH3RESA study
The TH3RESA study included 602 people diagnosed with metastatic, HER2-positive breast cancer that had been previously treated with a chemotherapy regimen that included a taxane and, after being diagnosed with metastatic disease, two or more regimens that included Herceptin and Tykerb.
More than half the people received four or more earlier treatments.
The people were randomly assigned to get either:
- 3.6 mg of Kadcyla per kg of body weight every 3 weeks (404 people)
- treatment chosen by their doctor (198 people)
As in the EMILIA study, early results from the TH3RESA study were promising, so people in the doctor’s choice treatment group were allowed to cross over to the Kadcyla treatment group if they wanted to do so; 47% crossed over to Kadcyla.
Overall survival was longer in people treated with Kadcyla:
- people treated with Kadcyla lived for 22.7 months
- people treated with their doctor’s choice of medicines lived for 15.8 months
People treated with Kadcyla also had fewer severe side effects than people treated with their doctor’s choice of medicines:
- 40% of people treated with Kadcyla had a severe side effect
- 47% of people treated with their doctor’s choice of medicines had a severe side effect
People treated with Kadcyla were more likely to have:
- low platelet count
People treated with their doctor’s choice of medicines were more likely to have:
- low white blood cell count
If you’ve been diagnosed with advanced-stage, HER2-positive breast cancer that has grown while being treated with a medicine other than Kadcyla, final results from these two studies offer encouraging news. It’s a good idea to talk to your doctor and ask whether Kadcyla might be a good treatment option for you and your unique situation.
For more information, visit the Breastcancer.org Kadcyla pages.
Editor's Note: On May 3, 2019, the FDA approved Kadcyla to treat early-stage HER2-positive breast cancer after surgery if residual disease was found after neoadjuvant treatment with taxane chemotherapy and Herceptin.
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