Monoclonal Antibody Shows Promise in Reducing Tumor Growth in Advanced Breast Cancer

Aspecifically designed monoclonal antibody has been shown to reducetumors in patients with late-stage breast cancer, according toa new study by scientists at Memorial Sloan-Kettering Cancer Center.

The monoclonal antibody, called rhuMAbHER2, prevents the growthof breast tumor cells by binding to certain proteins on the cellsurface. These proteins, known as cellular growth-factor receptors,are produced by the HER2 oncogene, a cancer-causing gene thatis abundant in certain types of cancer. The presence of high levelsof HER2, which is also called HER/2neu, is often associatedwith a poor prognosis.

In this phase II trial, 46 women with metastatic breast cancerwho had undergone several rounds of chemotherapy (a median ofthree times) and who expressed high levels of the HER2 proteinwere treated with rhuMAbHER2 for an 11-week period. The antitumoractivity of rhuMAbHER2 was then measured.

Partial or complete remission was observed in 11.6% of the patientstreated with the antibody. "Complete remission was observedin 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 Medicineat Memorial Sloan-Kettering Cancer Center and a coauthor of thestudy.

Another 37% of the study patients had either a minimal responseto the treatment or their disease remained stable. The antibodytreatment itself was very well tolerated by the patients, withno signs of toxicity. The results of this study were publishedin 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 regressionof human cancers. This opens profound opportunities for the futuredevelopment of new therapies to treat cancer."

Memorial Sloan-Kettering Cancer Center is among 100 North Americanhospitals participating in a phase III clinical trial of the HER2monoclonal antibody