Update: Targeted therapy for early-stage HER2-positive breast cancer continues to show benefit
People with early-stage HER2-positive breast cancer benefit from targeted therapy. This update includes new data on survival and the length of time without cancer returning. (Posted 6/20/24)
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RELEVANCE
Most relevant for: People with early-stage HER2-postive breast cancer.
It may also be relevant for:
- people with breast cancer
- men with breast cancer
- people with Her2-positive cancer
Relevance: Medium-High
Strength of Science: High
Research Timeline: Post Approval
What is this update about?
The KATHERINE trial compared trastuzumab emtansine (T-DM1, brand name Kadcyla) to trastuzumab (Herceptin) for people with HER2-positive breast cancer who still showed signs of cancer after surgery and postsurgery treatment. You can read our XRAY review on the initial results of this trial here.
This update from the KATHERINE trial covers a longer period. It compares the length of time without cancer returning and overall survival. People who took T-DM1 had better outcomes.
Why is this update important?
This trial was important because early-stage HER2-positive cancer is often treatable but can return years later. Research to understand why and when this happens and find treatments that more effectively prevent cancer from coming back are important.
Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC); a newer type of that better targets and kills cancer cells.
Study findings
This update is a second report of the phase 3 KATHERINE clinical trial results.
The KATHERINE trial tested a new drug called T-DM1 (trastuzumab emtansine or Kadcyla) for early-stage HER2-positive breast cancer. The trial was designed for people who still had signs of cancer in their breasts or after surgery and prior drug therapy. It compared a standard targeted therapy to a new treatment.
The 2018 results that were shared in our first report changed the standard treatment for this patient group to T-DM1 instead of trastuzumab. People in the trial had been followed for an average of nearly 3.4 years at the time of the first report.
The new results confirm that T-DM1 works better than trastuzumab alone.
On average, the new results added over 8 years of follow-up.
People who took T-DM1 after surgery went longer without cancer growth or spread than people who took trastuzumab. They also live longer according to results presented at the 2023 San Antonio Breast Cancer Symposium.
The 1,486 people who participated in the phase 3 KATHERINE trial all had signs of cancer in their breast or nodes after surgery. All were treated with chemotherapy and trastuzumab prior to surgery. This trial included people with both hormone-receptor-positive and hormone-receptor-negative disease.
The new results show that:
- People who took T-DM1 were less likely to have cancer return.
- 54% fewer people had cancer return compared to those who took trastuzumab alone.
- People from all subgroups (positive or negative nodes, race, age, score, etc.) benefited.
- T-DM1 reduced the risk of death by 34% over trastuzumab.
The final survival results will be reported in two years.
