Mayo Clinic researchers test breast cancer vaccine

Researchers at Mayo Clinic in Florida are conducting a phase II clinical trial that will test a vaccine designed to establish lifelong immunity against the development of precancerous breast lesions. Keith Knutson, Ph.D. (IMM ’05), director of the Mayo Clinic Discovery and Translation Labs Cancer Research Program, received a $3.7 million grant from the U.S. Department of Defense to conduct the breast cancer vaccine trial.

Ultimately, if the research is successful, the vaccine could substitute for current ductal carcinoma in situ therapy and become part of a routine immunization schedule in health women.

“We want to eliminate ductal carcinoma in situ, which means preventing disfiguring surgeries and toxic therapies in the 60,000 women who receive this diagnosis every year in the U.S.,” says Dr. Knutson, who designed the vaccine.

Only about 35 percent of precancerous breast lesions morph into cancer if untreated, but physicians cannot identify which lesions are potentially dangerous. So all women diagnosed with ductal carcinoma in situ undergo traditional therapy of surgery and possibly hormonal therapy and radiation.

Breast cancer vaccine followed by standard treatment in trial

Dr. Knutson and colleagues at all three Mayo Clinic campuses will test the vaccine in 40 to 45 patients diagnosed with ductal carcinoma in situ. These patients will be treated with the vaccine first. Six weeks later, they have surgery – lumpectomy or mastectomy – and other standard therapy. During the initial six weeks, physicians will monitor patients to see if ductal carcinoma in situ lesions reacted to the vaccine.

Targeted against HER-2 positive breast cancer

This vaccine is targeted against human epidermal growth factor 2 (HER-2), an oncogene known to play a role in the development and progression of an aggressive subtype of breast cancer known as HER-2 positive. The vaccine also has been tested in a phase I clinical study.

Dr. Knutson suspects that excess HER-2 proteins are expressed in all subtypes of breast cancer, including the most common one – estrogen-positive breast cancer. He says that the phase I study of the vaccine elicited an immune response in all tested individuals. The vaccine is designed to stimulate production of T cells that target initial development of ductal carcinoma in situ.

“We don’t know if the vaccine works just on HER-2 breast cancer,” says Dr. Knutson. “We believe that once an immune response is generated against the ductal carcinoma in situ, it doesn’t matter what subtype of cancer the lesion may become.”

If the trial is successful, advanced clinical trials could be designed to test the possibility that vaccination may be a safe alternative to conventional and problematic treatment for ductal carcinoma in situ, according to Dr. Knutson.

In 2015, Dr. Knutson and his team received a five-year $13.3 million U.S. Department of Defense Breakthrough Award to fund a phase II clinical trial testing a different breast cancer vaccine that he also designed. That vaccine is designed to prevent recurrence of triple-negative breast cancer.