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The ALTTO Breast Cancer Trial

  • Updated: 10/03/2011

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ALTTO: Optimising Targeted Therapy for HER2 Breast Cancer

The Adjuvant Lapatinib And/Or Trastuzumab Treatment Optimisation study, or ALTTO, is an international, phase III clinical trial of two targeted therapies for HER2-positive breast cancer. HER2 is a protein found in high levels on up to 25 percent of all breast cancers. Tumors that overproduce HER2 tend to be more aggressive and more likely to recur than those that do not.

The medications being tested in ALTTO, lapatinib (Tykerb®) and trastuzumab (Herceptin®), target HER2 in different ways. Researchers want to find out whether one drug will prove better than the other at helping women live longer without a recurrence of their disease, or if the two drugs will work better together.

The ALTTO study enrolled more than 8,000 participants in 50 countries on six continents. Women with HER2-positive breast cancer who have had their tumors completely removed by surgery were eligible to join. (See a summary of the ALTTO protocol, which includes contact information for the sites currently enrolling participants.)

On September 9, 2011, the leadership of ALTTO announced that it will discontinue Arm 2 of the trial. The Independent Data Monitoring Committee review of efficacy in the trial was triggered after a pre-specified number of events was reached, as outlined in the study’s protocol. For more information on this modification, go to the GlaxoSmithKline press release at and the ALTTO trial website at  

Beyond improving treatment for women with this type of breast cancer, the ALTTO trial represents a new level of international cooperation in the advancement of cancer care. ALTTO is one of the first global initiatives in which two large, academic breast cancer research networks covering different parts of the world have jointly developed a study in which all care and data collection are standardized, regardless of where patients are treated.

ALTTO is sponsored by the National Cancer Institute (NCI), part of the U.S. National Institutes of Health (NIH), and GlaxoSmithKline, the maker of lapatinib, and is being coordinated by The Breast Cancer Intergroup of North America (TBCI), based in the United States, and the Breast International Group (BIG) in Brussels, Belgium.

About the Trial

General Information

  • Targeted Cancer Therapies
    (Reviewed: 12/05/2012) - A fact sheet that describes targeted cancer therapies, which are drugs that block the growth and spread of cancer by interfering with specific molecules involved in carcinogenesis (the process by which normal cells are transformed into cancer cells) and tumor growth.
  • Lapatinib Ditosylate
    This page contains brief information about lapatinib ditosylate and a collection of links to more information about the use of this drug, research results, and ongoing clinical trials.
  • Trastuzumab
    This page contains brief information about trastuzumab and a collection of links to more information about the use of this drug, research results, and ongoing clinical trials.
  • Adjuvant and Neoadjuvant Therapy for Breast Cancer
    (Reviewed: 06/16/2009) - A fact sheet that explains different types of adjuvant therapy (treatment given after primary therapy to increase the chance of long-term survival) and neoadjuvant therapy (treatment given before primary therapy). Discusses side effects, risks, and benefits of adjuvant and neoadjuvant therapy for breast cancer.
  • Molecular Targets in Cancer Therapy
    The past two decades of biomedical research have yielded an enormous amount of information about the molecular events that take place during the development of cancer.