Breast Cancer Drug Breakthrough
A drug that targets only diseased cells has proven astonishingly effective against an aggressive form of early breast cancer — a long-sought breakthrough that has doctors talking about curing thousands of women each year in the United States alone.
The drug, Herceptin, is already used for advanced cancer. But in three studies involving thousands of women with early-stage disease, it cut the risk of a relapse in half.
"I feel happy for our patients. Happy because we have demonstrated that things are better," the Mayo Clinic's Dr. Edith Perez, a co-author of one of the studies, told The Early Show. "We don't have to wait 10 more years for data. The data is here today, and we're going to apply the information to patients today. So I'm happy. I'm also humble to be a part of this great study."
Several experts used words like "revolutionary," "stunning" and "jaw-dropping" to describe the findings.
"In 1991, I didn't know that we would cure breast cancer and, in 2005, I'm convinced we have," said Dr. Jo Anne Zujewski, head of breast cancer therapeutics at the government's National Cancer Institute.
Herceptin, known generically as trastuzumab, does not help everyone. For one thing, it is only for the estimated 20 percent of breast cancer cases in which tumors churn out too much of a protein known as HER2. In the recent studies, the drug was used along with standard treatments, including surgery and chemotherapy.
"This drug is not a chemotherapy drug. It's not a hormone drug. It's a type of special protein that attacks a protein in the tumor cell. It's very, very specific," Perez said. "If 50,000 women are diagnosed with this disease today or this year in the United States, a thousand will be alive in three years that would not have been alive had this drug not been used. So it could be a cure for these women."
Herceptin could be the biggest thing in cancer drugs since research a decade ago demonstrated the extraordinary effectiveness of tamoxifen, another medicine that transformed the treatment of the disease by homing in on cancer cells but sparing healthy ones.
Herceptin, made by Genentech, appears to have "changed one of the most worrisome kinds of cancers into one that may have a relatively good prognosis," said Dr. Ed Romond of the University of Kentucky.
He was one of the researchers who reported findings from three Herceptin studies Thursday in The New England Journal of Medicine. One was an international study sponsored by Herceptin's European marketer, Roche. The others were North American studies sponsored by the National Cancer Institute. The researchers followed more than 6,500 women with early-stage breast cancer.
In the first study, 220 women taking standard therapy for a year either developed breast cancer again, showed other kinds of tumors, or died. Only 127 did when Herceptin was added.
The two other studies, partly funded by Genentech, reached similar findings in their combined results. At three years, patients on Herceptin showed a disease-free survival rate that was 12 percentage points higher than without it.
The government approved the drug in 1998 for advanced breast cancer that has already spread within the body. But early-stage cases are much more common.
Many doctors are already embracing the drug for such women, cancer experts say, because details of the three studies were first publicized last spring at a medical conference.
"The strength of the evidence is so overwhelming at this point that it would be almost impossible to withhold this drug from the appropriate group of patients," said Dr. Gabriel Hortobagyi of the University of Texas, who is president-elect of the American Society of Clinical Oncology.
Genentech intends to apply to the U.S. government to add early-stage cancer use to Herceptin's label, spokeswoman Colleen Wilson said. But doctors are already free to prescribe the drug for early breast cancer on their own authority.
About 200,000 women are diagnosed with breast cancer each year in this country, and 40,000 die. About 30,000 American women will probably be taking Herceptin for breast cancer within a couple of years, curing perhaps 7,000 who would otherwise relapse, some doctors predicted.
However, doctors cautioned that some women get better without Herceptin, especially when there is little evidence that the cancer is spreading within the breast. Also, a small number taking the drug suffer heart failure.
"The side effects are not that severe compared to some of the side effects of chemotherapy," Perez said. Even though heart failure is severe, she said "it may occur in approximately 3 percent to 4 percent of patients who received Herceptin, as shown in our study. However, it's important to realize the majority of women improve rather rapidly with medications."
A year of Herceptin could cost $48,000, even at wholesale prices.
Tamoxifen has the same kind of benefit as Herceptin — a 50 percent reduction in risk — but works against another large class of cancer cases known as estrogen-positive.
Debbie Saslow, director of the breast cancer section of the American Cancer Society, said she was impressed by the Herceptin findings but wants to watch such patients for years. "I think it's way too soon to talk about a cure," she said.
It is also unclear whether Herceptin should be taken with chemotherapy drugs, soon afterward, or even years later. Herceptin appears so potent, some researchers said, that patients might someday be able to skip chemotherapy, radiation and surgery, which destroy both healthy and diseased tissue.
American sales of Herceptin leaped by two-thirds, to $215 million, in the three months ending Oct. 1, compared with the year's first quarter, according to Genentech.