Combining two chemotherapy drugs with trastuzumab (Herceptin) to treat women who have metastatic HER2+ breast cancer may offer physicians another choice in their treatment options.
At the 45th Annual Meeting of the American Society of Clinical Oncology (ASCO), researchers from the Mayo Clinic campus in Florida report that using a combination of capecitabine, vinorelbine, and trastuzumab offers a treatment option that is at least as beneficial as other current options - and doesn't cause hair loss in patients.
"This is a very well tolerated regimen. The combination is a good example of an excellent therapeutic ratio: good activity and low toxicity," says the study's senior investigator, Edith Perez, M.D., director of Mayo Clinic's Breast Center in Jacksonville.
The clinical trial is the first in the United States to study this particular combination of therapies in patients with HER2+ metastatic breast cancer, researchers say. The chemotherapy regimen was previously tested in Europe and demonstrated good anti-tumor activity and low toxicity, so Mayo researchers combined it with Herceptin, says the study's lead author, Winston Tan, M.D., a medical oncologist at Mayo Clinic.
Sixty-seven percent of the 45 patients in this trial responded to treatment, with their tumors decreasing in size by at least 30 percent. Historic response to conventional drug regimens (one chemotherapy drug with Herceptin) that are currently used to treat metastatic HER2+ breast cancer is about 50 percent, Dr. Tan noted.
"The results are encouraging, and would support a larger, randomized Phase III study," he says. "This is a Phase II study of this triple combination, so we would need to study this treatment against the standard best two-drug treatment in a randomized Phase III study to know if this triplet is more effective."
"This regimen seems to be a very reasonable choice, and it offers the added advantage that women who use it do not lose their hair," he says. The drug combination used most commonly for patients with HER2+ breast cancer that has spread - paclitaxel or docetaxel with trastuzumab - always causes hair loss, Dr. Tan says.
All of the agents are approved for use by the U.S. Food and Drug Administration for cancer, although vinorelbine has not been approved for this particular treatment regimen in the U.S., the researchers say.
Capecitabine chemotherapy is not usually paired with trastuzumab because some studies had suggested it does not offer a synergistic, or additive, benefit. However, Dr. Tan says that newer research has shown the combination is in fact promising.