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2 breast cancer drugs show promise

Boston doctor leads large trials

By Carolyn Y. Johnson
Globe Staff / December 8, 2011
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Two drugs tested in patients with advanced breast cancer significantly lengthened the time before their tumors worsened, according to studies published yesterday, and physicians said the treatments might eventually benefit many who are fighting the second most common cancer in US women.

The results of the large international trials, both led by an oncologist at Massachusetts General Hospital, are likely to drive the approval of the two drugs and to change treatments for women with the two major types of breast cancer, specialists said. These cancers account for about 80 percent of cases, and many of these patients suffer relapses when their initial treatments stop working.

The research, paid for by the drug makers, is generating considerable excitement and anticipation among cancer specialists, who said in interviews that the results are some of the strongest data seen in years for new breast cancer therapies. The papers were published online yesterday by the New England Journal of Medicine and are scheduled to be presented today and tomorrow at the San Antonio Breast Cancer Symposium.

One study focused on women with a type of breast cancer known as HER2 that had spread. They were given either a new drug called pertuzumab, combined with standard therapy, or standard therapy alone. Those in the pertuzumab group gained an additional half year before their tumors began to grow again compared with the women on standard therapy. The study was called Cleopatra.

The second study involved adding the drug everolimus to a standard hormone therapy. When put on this regimen, women with advanced breast cancer driven by the hormone estrogen had an additional four months before their cancer began to progress, compared with patients given just standard therapy. That study was called BO-LERO-2.

Neither trial has lasted long enough yet to determine whether the drugs would extend patients’ lives. Still, Dr. José Baselga, who is chief of hematology-oncology at Mass. General and who led the studies, said: “We’re talking about a very significant improvement in disease-free survival. These are meaningful timelines.’’

He added that the results show the promise of similar drugs and targeted therapies that are in the pipeline.

“This is an exciting time; it’s a crazy time, e-mails flowing one way and another,’’ he said. “We’re all talking. We have not been so active in a long time.’’

An estimated 230,000 invasive breast cancers will be diagnosed this year in the United States, according to the American Cancer Society, and nearly 40,000 women will die of the disease. It is the most common cancer among women after skin cancer.

The makers of the two drugs will seek approval from the US Food and Drug Administration. Genentech, which is developing pertuzumab, filed its application this week, and Novartis plans to file by the end of the year for everolimus. Baselga said he has consulting agreements with Novartis and Roche, which owns Genentech.

The new findings come shortly after the FDA withdrew its approval for using Avastin, a drug approved for several cancers, for patients with metastatic breast cancer because initial positive findings did not hold up. Cancer specialists are cautious after that experience but said that the results for the new drugs are strong and likely to hold up.

“Both are really significant advances,’’ said Dr. Eric Winer, director of the breast oncology center at Dana-Farber Cancer Institute. He added that the studies are promising for their possible future impact, as the drugs are tested in broader sets of patients or pave the way for similar drugs in earlier development. Pertuzumab is now being tested in a large, late-stage trial in women with early-stage breast cancer.

Pertuzumab, a drug that binds to a specific protein, was tested in 808 patients with metastatic breast cancer. The women had tumors with extra copies of the protein HER2, present in about a fifth of women with breast cancer. Half were randomly assigned to receive the drug, along with another medication called Herceptin and chemotherapy, and half received the combination with a placebo. The average time until the cancer returned in the placebo group was a little over a year, compared with a year and a half in patients who received pertuzumab. There were some side effects, including diarrhea and a drop in white blood cells.

“When you start seeing something measured in half a year - to a patient and physician that would be viewed as significant,’’ said Dr. William Gradishar, a professor of medicine at Northwestern University.

In the other study of 724 postmenopausal patients, women with advanced breast cancer sensitive to the hormone estrogen had cancers return after an average of seven months if they were randomly assigned to get a drug combination that included hormone therapy and everolimus, a drug approved to treat other cancers. The cancers began to progress after just three months among those receiving hormone therapy and a placebo. The drug caused fatigue, high blood sugar, and oral ulcers.

There are caveats to the positive results, such as side effects, the anticipated high price of the drugs, and whether they would be covered by insurance. The companies said pricing data for the drugs’ use among breast cancer patients was not available. Everolimus currently costs $6,500 to $7,000 for a month’s supply, depending on dose.

But the research shows the power of different approaches. Among estrogen-sensitive cancers that are successfully treated by hormone therapy, the disease commonly returns. Everolimus targets the cancer’s resistance, the mechanism the tumor uses to escape the drug. Pertuzumab shows the strength of targeting a protein that drives the cancer.

“These two studies are great examples showing how the research community has been able to translate understanding of the biology of disease into meaningful therapeutic advances,’’ said Dr. Sharon Giordano, an oncologist at the University of Texas M.D. Anderson Cancer Center.

The need for new therapies is urgent, more than a decade after Herceptin was first introduced.

Debbie Prescott, 53, of Atkinson, N.H., was diagnosed in 2002 with breast cancer that had metastasized to her liver. The diagnosis sent her into an emotional black hole, wondering if she should still do routine things like send out Christmas cards.

She went to Mass. General, where she received Herceptin, aimed specifically at the protein that was driving her cancer, and chemotherapy. She did well on the drugs and by 2004 had no signs of the cancer. But three years ago, the cancer returned. She began taking Herceptin again, but it was not working as well.

“The Herceptin on its own wasn’t keeping the cancer at bay. There was slow progression,’’ Prescott said.

She entered a clinical trial - not one of those being published today - and is doing well. “I have sent Christmas cards,’’ she said.

Carolyn Y. Johnson can be reached at Follow her on Twitter @carolynyjohnson.

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