Aspecifically designed monoclonal antibody has been shown to reduce tumors in patients with late-stage breast cancer, according to a new study by scientists at Memorial Sloan-Kettering Cancer Center.
The monoclonal antibody, called rhuMAbHER2, prevents the growth of breast tumor cells by binding to certain proteins on the cell surface. These proteins, known as cellular growth-factor receptors, are produced by the HER2 oncogene, a cancer-causing gene that is abundant in certain types of cancer. The presence of high levels of HER2, which is also called HER/2neu, is often associated with a poor prognosis.
In this phase II trial, 46 women with metastatic breast cancer who had undergone several rounds of chemotherapy (a median of three times) and who expressed high levels of the HER2 protein were treated with rhuMAbHER2 for an 11-week period. The antitumor activity of rhuMAbHER2 was then measured.
Partial or complete remission was observed in 11.6% of the patients treated with the antibody. "Complete remission was observed in a patient whose disease had metastasized to her chest wall. After 3 years she remains disease-free," noted Larry Norton,MD, Chief, Breast Cancer Medicine Service, Department of Medicine at Memorial Sloan-Kettering Cancer Center and a coauthor of the study.
Another 37% of the study patients had either a minimal response to the treatment or their disease remained stable. The antibody treatment itself was very well tolerated by the patients, with no signs of toxicity. The results of this study were published in the March 1996 issue of the Journal of Clinical Oncology.
"This is very promising research," said Dr. Norton. "These results present the proof of a scientific principle, that drugs aimed at growth-factor receptors can cause the regression of human cancers. This opens profound opportunities for the future development of new therapies to treat cancer."
Memorial Sloan-Kettering Cancer Center is among 100 North American hospitals participating in a phase III clinical trial of the HER2 monoclonal antibody