Breast cancer vaccine in the making

Breast cancer is the most common cancer in women. In the US alone, it is estimated that 40,000 women will die from deadly disease this year. Mayo Clinic diagnoses and treats approximately 1,300 new breast cancer patients each year.

For the last 25 years, Mayo Clinic researcher Dr. Sandra Gendler has been studying a large molecule called MUC1 which is a naturally occurring protein. Her life’s work led to the development of a breast cancer vaccine. Dr. Gendler describes MUC1 as a protein that looks like a “bottle brush, covered with sugar”. These proteins are found on surfaces of cells in the lungs, breasts, stomach, intestine and reproductive tract. When cancer occurs, the cell architecture collapses and MUC1 with abnormal sugars are produced in abundant amount. These MUC1 proteins are found on more than 90% of breast cancers and are said to be involved in 70% of the breast cancer deaths of humans in 2007.

Dr. Gendler was the first scientist to clone MUC1 successfully by developing transgenic mice that produce human version of MUC1. She and her colleagues discovered that the production of MUC1 resulted in tumors in the mammary glands of these transgenic mice. This protein, however, can also act as an antigen and triggers weak immune response.

 Dr. Gendler and her team of researchers are now working together to develop a vaccine made of peptides based on MUC1 and HER2/neu, a molecule associated with 25% of breast cancers. These peptides were combined with adjuvants which can trigger immune responses and production of white blood cells. The preclinical studies showed that the vaccine can prevent tumor formation and slowed down the growth of existing tumors in mice.

 “The nice thing about MUC1’s being a target is that it is expressed in just about all breast cancers,” says Dr. Svetomir Markovic, a team member whose specialty is the development and clinical testing of cancer vaccines and immune boosting agents. “If this vaccine works, it will help most patients. Based on our laboratory data, this should work better than prior efforts.”

If this vaccine works in humans, this can be used with tamoxifen, an estrogen-based therapy which is commonly used as temporary post-treatment in preventing the recurrence of tumors. The vaccine, however, won’t be available anytime soon. Clinical research in general takes time.

According to Dr. Markovic

First, we need to see if the vaccine will produce an immune response. If it does, then we do another trial and ask whether that immune response will protect patients from cancer relapses. It will take at least five to seven years before we know.”

For breast cancer patients, that’s a very long time. But still we are crossing our fingers, if not for now but for generations of women to come.

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