October 2, 2012
(The New York Times News Service) -- An experimental drug from South San Francisco's Genentech Inc. improved survival rates by nearly six months in late-stage breast cancer patients whose tumors had heightened levels of a protein molecule called HER2.
The data, published Monday in the New England Journal of Medicine, found that the drug, known as T-DM1, reduced the risk of death by 32 percent when matched against a standard therapy, prolonging lives by a median of 30.9 months compared to 25.1 months. Patients treated with T-DM1 also had fewer side effects.
"This is not a trivial result. This is a big result," said Mark Sliwkowski, a senior scientist at Roche-owned Genentech who has been instrumental in the discovery of all of the company's HER2-targeted medicines.
In as many as 25 percent of breast cancer patients, the cells make an excessive amount of the protein HER2, or human epidermal growth factor receptor 2. While HER2-positive cancers can be particularly aggressive, the presence of the overabundance of HER2 gives researchers something to target.
T-DM1, or trastuzumab emtansine, is a new generation of medicines that build upon the company's first HER2-targeted drug, Herceptin, approved in 1998.
The therapy combines Herceptin with a potent tumor-killing chemotherapy. The combination binds to the HER2-positive cancer cells to block the signals they use to communicate and divide out of control and calls on the body's immune system to attack those abnormal cells. T-DM1 goes for the kill by delivering the chemotherapy directly to the cell.
The clinical trial results, which were also reported Monday at the European Society of Medical Oncology meeting in Vienna, Austria, involved 991 patients with the HER2-positive disease who had previously been treated with Herceptin and another type of drug called a taxane. The patients were treated with T-DM1 or a combination of Roche's Xeloda and Tykerb, which is made by GlaxoSmithKline.
"T-DM1 is going to revolutionize the way we treat HER2-positive breast cancer and the data is very exciting," said Dr. Hope Rugo, UCSF breast cancer specialist and an investigator in T-DM1 studies, speaking from Vienna.
While some patients treated with T-DM1 experienced side effects including low platelet count, the drug was much better tolerated than standard therapy.
Genentech, which filed in August for the U.S. Food & Drug Administration to approve T-DM1, has requested an expedited review, which means a decision could be made in six rather than 10 months. The company has not yet heard back from the FDA on whether it will get the faster review.
For patients like Anne La Londe-Berg, that day can't come soon enough.
La Londe-Berg, 57, of Santa Rosa, started taking T-DM1 as part of a trial in 2008 after her breast cancer had recurred multiple times since she was first diagnosed in 1996. She had just been released from the hospital and was very ill, but said she started feeling better soon after taking the drug.
La Londe-Berg, mother of three sons, said she's been able to keep working as a special education administer in Napa Valley and has experienced almost no side effects.
"For me, it was lifesaving," she said, adding that she's also pleased the drug does not cause hair loss. "I'm growing old and I never thought I was going to grow old."
Genentech in June received FDA approval for another drug, Perjeta, which also targets the HER2-positive disease but in a different way. Perjeta is designed to be used in combination with Herceptin or T-DM1.
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