Biomarker analysis identified women most likely to benefit from T-DM1

April 7, 2013, American Association for Cancer Research

For women with metastatic, HER2-positive breast cancer, the amount of HER2 on their tumor might determine how much they benefit from a drug called trastuzumab emtansine (T-DM1), according to data from a subanalysis of the phase III clinical trial that led the U.S. Food and Drug Administration to approve the drug on Feb. 22, 2013. These findings were presented by José Baselga, M.D., Ph.D., physician-in-chief at Memorial Sloan-Kettering Cancer Center in New York, N.Y., at the AACR Annual Meeting 2013, held in Washington, D.C., April 6-10.

"EMILIA was a landmark phase III clinical trial," said Baselga. "It showed that T-DM1 prolonged progression-free and overall survival for patients with HER2-positive that had been previously treated with trastuzumab and a taxane chemotherapy compared with lapatinib plus . Also, it provided proof-of-concept that a new class of drugs called antibody-drug can benefit patients."

Antibody-drug conjugates consist of an antibody attached to a toxic chemotherapy, according to Baselga. In the case of T-DM1, the antibody is trastuzumab and the toxic chemotherapy is emtansine. Trastuzumab recognizes the protein HER2, which is found at high levels in HER2-positive breast cancers, and targets the emtansine to the HER2-positive , which are killed by the toxic chemotherapy.

In this subanalysis, Baselga and colleagues analyzed tissue samples from patients enrolled in EMILIA to examine whether tumor levels of HER2, as assessed by the amount of HER2 messenger ribonucleic acid (mRNA), affected . Patients with tumor samples expressing greater than the median amount of tumor HER2 mRNA were considered to have high levels of HER2. Those with tumor samples expressing the median amount of tumor HER2 mRNA or less were considered to have low levels of HER2.

"Even though everyone enrolled in the clinical trial had breast cancer expressing elevated levels of HER2, we know that each person's tumor has different molecular features," said Baselga. "Even the degree to which HER2 expression is elevated differs from patient to patient."

Consistent with the prior analysis, he and his colleagues found that all patients treated with T-DM1 had significantly longer progression-free and overall survival compared with those treated with lapatinib and capecitabine (9.6 months progression-free survival versus 6.4 months; and 30.9 months for overall survival versus 25.1 months).

Patients with tumors expressing higher levels of HER2 derived greater benefit from treatment with T-DM1 compared with patients with tumors expressing lower levels of HER2: Overall survival was 34.1 months for those with high levels of HER2 versus 26.5 months. For patients with tumors expressing higher levels of HER2, those receiving T-DM1 had a 47 percent decreased risk for death compared with those receiving and capecitabine.

The researchers also investigated whether tumor mutations in the PIK3CA gene affected treatment response. According to Baselga, patients with PIK3CA-mutated, HER2-positive breast cancer normally do not respond as well to treatment with conventional HER2-targeted therapies such as trastuzumab compared with patients without PIK3CA mutations in their tumors.

However, for patients treated with T-DM1, PIK3CA mutation status did not significantly decrease progression-free survival.

"Our findings are an important step toward identifying the best therapy for individual with HER2-positive breast cancer," said Baselga. "HER2-positive is not a uniform disease; each patient is different. These data help us as we look to identify a panel of molecular features that we can use to make informed treatment decisions."

Kadcyla (ado-trastuzumab emtansine or T-DM1) is a trademark of Genentech, a member of the Roche Group.

Explore further: Enhancing the effectiveness of a breast cancer treatment

Related Stories

Enhancing the effectiveness of a breast cancer treatment

February 13, 2012
Breast cancers expressing the protein HER2 have a particularly poor prognosis. Treatment with trastuzumab (Herceptin) benefits some patients with HER2-positive breast cancer, but it is not as effective as had been hoped. ...

Treatment targeting PI3K may delay resistance to anti-HER2 therapy in breast cancer patients

January 23, 2013
Patients with HER2-positive breast cancer being treated with anti-HER2 therapy may be able to prevent or delay resistance to the therapy with the addition of a phosphatidylinositol-3 kinase inhibitor to their treatment regimens.

Phase II study shows new cancer drug combination significantly delays breast cancer progression

September 25, 2011
The first randomised trial to investigate the use of trastuzumab emtansine (T-DM1) – an antibody-guided drug – for the initial treatment of HER2- (human epidermal growth factor receptor-2) positive metastatic breast ...

Dual HER2 blockade significantly extends progression-free survival

December 8, 2011
Adding pertuzumab to a combination of trastuzumab and docetaxel chemotherapy extended progression-free survival by a median of 6.1 months in patients with metastatic HER2-positive breast cancer compared with patients who ...

Recommended for you

Modular gene enhancer promotes leukemia and regulates effectiveness of chemotherapy

January 18, 2018
Every day, billions of new blood cells are generated in the bone marrow. The gene Myc is known to play an important role in this process, and is also known to play a role in cancer. Scientists from the German Cancer Research ...

Researchers find a way to 'starve' cancer

January 18, 2018
Researchers at Vanderbilt University Medical Center (VUMC) have demonstrated for the first time that it is possible to starve a tumor and stop its growth with a newly discovered small compound that blocks uptake of the vital ...

Researchers develop swallowable test to detect pre-cancerous Barrett's esophagus

January 17, 2018
Investigators at Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center have developed a simple, swallowable test for early detection of Barrett's esophagus that offers promise ...

Scientists zoom in to watch DNA code being read

January 17, 2018
Scientists have unveiled incredible images of how the DNA code is read and interpreted—revealing new detail about one of the fundamental processes of life.

Presurgical targeted therapy delays relapse of high-risk stage 3 melanoma

January 17, 2018
A pair of targeted therapies given before and after surgery for melanoma produced at least a six-fold increase in time to progression compared to standard-of-care surgery for patients with stage 3 disease, researchers at ...

Dulling cancer therapy's double-edged sword

January 17, 2018
Researchers have discovered that killing cancer cells can actually have the unintended effect of fueling the proliferation of residual, living cancer cells, ultimately leading to aggressive tumor progression.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.