New Study Testing Immune-Boosting Antibody Against Metastatic Breast Cancer

 Behind the Cancer Headlines®

July 18, 2003 


UCLA's Jonsson Cancer Center is testing an experimental immune system-boosting antibody that could one day help women who have not responded to conventional chemotherapy treatments for metastatic breast cancer.  

The Phase I study uses an antibody directed at the MUC1 protein, which is exposed on the surface of cancer cells in more than 90 percent of women who have breast cancer. In normal tissues, MUC1 is a protein that is literally sugar-coated, being completely surrounded by carbohydrate molecules. In rapidly growing cancer cells, the sugar structures do not form correctly and the protein core of MUC1 is exposed. Researchers believe this exposed protein core can become a new target that is vulnerable to attack by antibodies.  

In laboratory studies, the antibody called R1550 (formerly Therex) has been shown to bind tightly to MUC1 on cancer cells and then activate immune system cells to kill the cancer. Using antibodies to encourage the body's own immune system to do its job is a different way of fighting cancer. Other targeted therapies help cancer-killing drugs work better, but this study seeks to engage the natural immune system cells to do the killing.  

"Our study is a real test of an antibody as immunotherapy for breast cancer. The way this antibody works seems to be dependent upon its ability to engage the immune system after it binds to MUC1 on the tumor cells," said Dr. Mark Pegram, director of the Women's Cancer Program Area at UCLA's Jonsson Cancer Center and principal investigator for the study. "Sadly, women who have not responded to chemotherapy don't have too many other treatment options. We believe this antibody has the potential to be a less toxic alternative to conventional chemotherapy treatment for women with recurrent breast cancer."  

The research study is recruiting women volunteers who have already been treated with the chemotherapy drugs Taxol or Taxotere and an anthracycline drug such as Adriamycin, but who have relapsed despite prior treatment.  

An earlier study conducted in the United Kingdom showed the antibody was well-tolerated in breast cancer patients.  

UCLA's Jonsson Cancer Center is currently the only site in the world testing this new antibody, Pegram said.  



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