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T-DM1 Overall Survival Data Released, FDA Grants Priority Review

The FDA granted T-DM1 accelerated review, just as updated overall survival results were announced

January 24, 2013

Written By Josh Fernandez, Digital Media Specialist
Reviewed By Julie R. Gralow, MD

An article in the New England Journal of Medicine with updated overall survival results from the international EMILIA study of trastuzumab emtansine (T-DM1) was published two days after the medicine’s developer, Genentech/Roche, announced that the U.S. Food and Drug Administration will grant the medicine a priority review. 

T-DM1 is an antibody-drug conjugate which pairs chemotherapy with targeted medicine to deliver chemotherapy’s powerful effects directly to the tumor while sparing healthy cells from its toxic effects. It is currently being studied in HER2 positive cancers and has generated a lot interest since the June 2012 American Society of Clinical Oncology (ASCO) meeting, when results of the EMILIA study were first presented. Compared to standard therapy, T-DM1 showed an increase in progression-free survival, the time during and after treatment the cancer remains stable.

When Genentech announced updated results ahead of print in the New England Journal of Medicine online, T-DM1 received additional attention because these results showed that people with HER2 positive metastatic breast cancer treated with this medicine also had a significantly longer rate of overall survival, the time a person lives from the beginning of the study until death from any cause. 

Prior to approval, each medicine marketed in the United States must go through a detailed FDA review process.  In a Nov. 6 press release, Genentech announced that the FDA had granted T-DM1 priority review. This means the time it takes the FDA to review the medicine will be reduced because it offers major advances in treatment. 

The FDA will complete the review by Feb. 26, 2013. The Genentech release mentioned that the European Medicines Agency (EMA) is also reviewing T-DM1.

Learn more about the background and reason for the study.

Learn more about the study structure.


Data from EMILIA suggested that participants assigned to T-DM1 experienced fewer side effects. Median progression-free survival was 3.2 months longer with T-DM1, increasing from 6.4 months with XL to 9.6 months with T-DM1. XL, or capecitabine/lapatinib, is the standard therapy for metastatic HER2 positive breast cancer that has progressed despite treatment with trastuzumab (Herceptin).

Data also suggested that T-DM1 increased overall survival, but investigators couldn’t confirm this until the findings reached statistical significance, meaning the differences are unlikely to have happened by chance. The second analysis showed that overall survival increased nearly six months (from 25.1 months to 30.9 months).

Estimated 1-year survival rates were 85.2 percent for those receiving T-DM1 and 78.4 percent for the group treated with XL. Two-year survival rates were 64.7 percent for the T-DM1 group and 51 percent for the XL group.

What This Means For You

T-DM1 continues to show potential as an effective, less toxic treatment for HER2 positive metastatic breast cancer.

According to the FDA’s website, a standard review is a 10-month time frame for FDA review of a new medicine application.  During a priority review, additional attention and resources are directed toward medicines that have the potential to significantly advance treatment. Advances may include more effective treatment, prevention or diagnosis of disease, or elimination or substantial reduction of side effects. 

Priority review does not affect the FDA’s standards or the quality of scientific evidence needed for approval. 

If approved, women with HER2 positive metastatic breast cancer could have T-DM1 as a treatment option before mid-2013. 

“In view of the efficacy and excellent safety profile of this agent, the ongoing randomized trial evaluating use in the first-line setting and the many other studies examining trastuzumab emtansine across abroad range of disease contexts, it seems likely that a major shift in our basic approach to the treatment of HER2-positive cancers is imminent,” Beverly Teicher, PhD, and James Doroshow, MD, wrote in an editorial in the New England Journal of Medicine along with the updated results.

Living Beyond Breast Cancer will continue to report on updates for T-DM1 and other treatments for HER2 positive breast cancer on

For more information on the medicine review process, visit the FDA’s website.

To learn more about the updated findings of the EMILIA study, visit the New England Journal of Medicine’s website.

To read more about antibody-drug conjugates, read Dr. Teicher and Dr. Doroshow’s editorial on the New England Journal of Medicine’s website.

Teicher, Beverly A., Doroshow, James H. The Promise of Antibody–Drug Conjugates. New Engl J Med 2012 Nov. 8: 367:19, 1847-1848

Verma, Sunil, Miles, David, et al. Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer. New Engl J Med 2012 Nov. 8: 367, 1783-1791