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Mammastatin Protein Studied As Breast Cancer Treatment and Predictor (dateline March 23, 2000)

Researchers at the MD Anderson Cancer Center in Houston, Texas are investigating whether injections of a protein called mammastatin may help treat women with advanced breast cancer.  Mammastatin is thought to be a naturally occurring protein produced by breast cancer cells. The protein was first identified in 1986 and has been determined in preliminary research to be lacking in the majority of breast cancer patients and healthy women who have a family history of breast cancer. In a clinical trial, researchers are monitoring 36 patients who have been injected with mammastatin to see if it helps slow the growth of breast cancer cells. Researchers are also investigating whether testing a woman’s mammastatin levels could predict her risk of breast cancer.

According to Biotherapies, Inc., a cancer research company, mammastatin blocks the growth of cancer cells in the breast. Dr. Paul Ervin, Jr. discovered the mammastatin protein while conducting research at the University of Michigan’s Cancer Center. According to Dr. Ervin’s research:

  • Mammastatin is a protein produced by healthy women
  • Mammastatin is thought to block breast cell growth
  • Mammastatin may be missing in approximately 90% of breast cancer patients
  • Mammastatin could be used as a treatment to inhibit breast cancer cell growth
  • Mammastatin is non-toxic and is thought to only affect breast cancer cells

In 1996, a preliminary study involving 34 late-stage breast cancer patients revealed that regular injections of mammastatin into the bloodstream stopped breast cancer cell growth in 60% of patients. Five of the 34 patients (15%) experienced either a significant reduction of breast cancer or complete remission. No negative side effects were seen in any of the patients as opposed to the sometimes harsh effects of standard breast cancer treatments such as chemotherapy or radiation therapy. Mammastatin does not appear to affect the growth of cells in other parts of the body. 

Mammastatin May Predict Breast Cancer

In addition to testing the safety and effectiveness of mammastatin as a breast cancer treatment, a blood test called a mammastatin serum assay (MSA) is currently being tested to measure the levels of mammastatin in a woman’s body. Researchers believe this blood test may help physicians identify a woman’s risk of developing breast cancer. In a preliminary study of 150 healthy women and 450 breast cancer patients, mammastatin was present in the blood of over 85% of healthy women but absent in over 90% of breast cancer patients. Mammastatin was also absent in 15% of healthy patients, which the researchers say is consistent with the estimate that one in eight women will develop breast cancer.

Though research is promising, physicians do not expect the MSA blood test or any other type of blood test to replace mammography any time soon. Mammography is the only exam approved by the U.S. Food and Drug Administration (FDA) to screen for breast cancer in asymptomatic women (women who show no signs or symptoms of the disease) and is considered the gold standard in detecting breast cancers at an early stage. John Glaspy, MD, a breast cancer specialist at the UCLA Jonsson Cancer Center, told IVD Technology Magazine that he has not seen any reliable data on a blood test that would be useful in the primary diagnosis of breast cancer.

More likely, if further research is successful, the MSA blood test may be useful in determining whether breast cancer will return (recur) in patients who have had advanced (metastatic) breast cancer. Researchers also hope to investigate more aspects of the mammastatin protein, including:

  • Determining the mechanism of action of mammastatin
  • Cloning the gene for mammastatin
  • Finding proteins related to mammastatin that might be effective in treating other cancers
  • Determining other ways to administer mammastatin

Additional Resources and References