Mayo Clinic Breast Cancer Vaccine Candidate Moves into Second Phase

The Mayo Clinic announced it is moving forward with a series of clinical trials for various breast cancer vaccines.

Most experimental breast cancer vaccines have either not moved beyond preclinical testing, or have not shown a significant clinical response.

These Mayo Clinic vaccine candidates are designed to prevent cancer recurrence in patients who have already received initial treatment, and appear disease-free.

These vaccine candidates are currently in a Phase II clinical trial, with approximately 300 women enrolled.

The primary objective of 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.

According to researchers, about 40 percent of individuals diagnosed with triple-negative breast cancer will relapse over the course of five or six years.

Triple negative breast cancer (TNBC) is a distinct subtype of breast cancer with unique pathologic, molecular and clinical behavior.

Triple-negative breast cancer is more likely to occur before age 50, versus age 60, which is more typical for other breast cancer types. A previous study found that black women were 3 times more likely to develop triple-negative breast cancer than white women.

Keith Knutson, Ph.D., is the principal investigator, Breakthrough Award, Breast Cancer Research Program, Department of Defense, 2016-2021.

The Mayo Clinic’s Florida campus was awarded the Breakthrough Award from the U.S. Department of Defense’s Breast Cancer Research Program to fund a phase II clinical trial testing the ability of a folate receptor alpha vaccine to prevent recurrence of this aggressive cancer following initial treatment.

If ultimately successful, the vaccine could substitute for current ductal carcinoma in situ therapy and may become part of a routine immunization schedule in healthy women.

“We ultimately 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.

“Eliminating ductal carcinoma in situ also would reduce the overall breast cancer burden significantly,” adds Dr. Knutson.

“Ductal carcinoma in situ is a significant health problem, accounting for about 20 percent of U.S. cases of breast cancer.”

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 said that the phase I clinical study of the vaccine was successful at eliciting an immune response in all tested individuals.

“We don’t know if the vaccine works just on HER-2 breast cancer.”

“We believe that once an immune response is generated against the ductal carcinoma in situ lesion, it doesn’t matter what subtype of cancer the lesion may become,” said Dr. Knutson.