Zeroing In on Breast Cancer

May 2006 Special Advertising Section

Dede Strand was diagnosed with breast cancer in August 2005. Now, less than a year later, she is looking forward to having her hair grow back and planning her wedding, her future bright thanks in part to a drug called Herceptin. “I feel great,” says the forty-five-year-old Eagan woman, who also underwent surgery, chemotherapy, and radiation. “You get a new lease on life, and it’s amazing."

Herceptin and a newer drug with limited availability, Lapatinib, are called “targeted therapies” because they zero in on specific types of breast cancer cells. Another new drug, Avastin, also shows promise as a treatment for breast cancer. In clinical trials, Herceptin—the leader in the pack of new therapies—reduced the chance of a recurrence of breast cancer by 50 percent, and it cut the risk of dying of the disease within two years by 33 percent. Those dramatic results have given Strand and other patients with tumors that overexpress the protein HER2 new hope for a disease-free future.

“Chemotherapy, which used to be our standard, will kill off cancer cells, but it doesn’t target them specifically, whereas these therapies target cancer cells,” says Colleen Morton, MD, a hematologist and oncologist with HealthPartners in St. Paul. Because they don’t kill healthy cells, these drugs also generally cause fewer side effects.

Herceptin Makes Its Mark
Approved by the U.S. Food and Drug Administration in 1998, Herceptin (the trade name for trastuzumab) is a monoclonal antibody that blocks HER2’s ability to help cancer cells proliferate and spread. Antibodies are a component of the immune system; monoclonal antibodies are mass-produced in a laboratory. Herceptin can be given in combination with chemotherapy to the 20 to 30 percent of women with the more aggressive type of breast tumors that overexpress HER2.

However, it doesn’t work for everyone, and it is not without risks, says Nicole Hartung, MD, an oncologist with Minnesota Oncology and Hematology in Woodbury. “Herceptin has a 5 percent risk of heart failure after having chemotherapy, so you don’t want to give it to everyone unless there’s a significant benefit to it,” she says. “If you are (lymph) node-positive and you completed your chemotherapy within the last six months, then yes, it might be something to think about, but if it’s been more than six months, there might not be a benefit to it.”

Lapatinib Steps In
Like Herceptin, Lapatinib targets HER2-positive cancer cells, but it has the added benefit of also countering HER1, a close relative of HER2. The ability to inhibit HER1 means that it could help a broader range of patients, and preliminary trial results have shown encouraging tumor regression. It also comes in pill form, which would be much more convenient than having to travel to a clinic for an intravenous infusion.

Lapatinib, which is used in conjunction with chemotherapy, is experimental and currently available only to women with metastatic cancer who take part in a clinical trial. “It’s a very promising drug that may work when Herceptin fails,” Morton says. “It’s kind of exciting that we have another new targeter.” The drug’s maker, GlaxoSmithKline, is aiming to have it available by 2007.

Avastin Takes Aim
Avastin, an intravenous drug that has helped prolong the lives of people with colon cancer and is being tested in clinical trials for use in lung and breast cancers, helps shrink tumors by interfering with the development of the blood vessels that cancers need to grow.

Avastin (the trade name for bevacizumab) has been FDA-approved for colon cancer since 2004, but oncologists are using it in some patients with metastatic breast cancer. Because it works by a different mechanism than Herceptin and Lapatinib, it can be used to treat both HER2-positive and HER2-negative cancers. “This is for anyone with metastatic breast cancer, as long as they don’t have a risk of bleeding or brain metastases,” says Amy Stella, MD, an oncologist with North Memorial Medical Center’s Humphrey Cancer Institute in Robbinsdale. Early data has suggested that Avastin may be beneficial in prolonging life for several months in women with breast cancer when it is used in conjunction with certain types of chemotherapy, but it is too soon to be sure, Morton says. “This hasn’t turned out to be a wonder drug, by any means,” she says.

Complicating matters, Genentech, the maker of both Herceptin and Avastin, has announced that it plans to charge about $100,000 a year for Avastin for lung or breast cancer—a price that critics say could dissuade some patients without insurance coverage from seeking treatment. Herceptin costs about $40,000 per year, but insurance pays for it because it is approved specifically for breast cancer.