Of all 42 patients who had enrolled in the study, including the eight who continued to receive treatment after the study had been halted, 26 percent in the chemotherapy arm achieved pathologic complete remission, compared with 65.2 percent in patients treated with both Herceptin and chemotherapy, according to the JCO study.
If the trial had enrolled all 164 patients, statisticians calculated a 95 percent probability that the combination of Herceptin and chemotherapy would prove superior, Buzdar says.
Giving a new combination of drugs together and for a longer time
Between 25 percent and 30 percent of breast cancers are known to over-express the human epidermal growth factor receptor 2 (HER-2), a protein that fuels the growth, and thus the aggressiveness, of the cancer. Herceptin is a monoclonal antibody drug designed to block the action of these receptors, but use of the agent by itself has shown only modest benefits.
The Food and Drug Administration approved use of Herceptin in 1998 for treatment of metastatic breast cancer in combination with chemotherapy. The long term outcome of such treatment, however, has not yet been established, according to Buzdar, and several large and lengthy clinical trials are now under way to test for cancer recurrence and survival after use of Herceptin with chemotherapy.
But researchers at M. D. Anderson wanted to test use of the drug combination in patients with earlier stage breast cancer, defined as stage II to IIIa. In order to immediately see if it had an effect on cancer, they sought to use it before surgery, so that when breast tissue was later
Contact: Nancy Jensen
University of Texas M. D. Anderson Cancer Center