A vaccine for breast cancer may be near

An experimental vaccine may be able to prevent or treat a particularly aggressive form of breast cancer, according to new findings from UW Medicine researchers.

Driving the news: In a decade-long Phase I human trial, the vaccine created a strong immune response to proteins that cause tumors to grow aggressively, researchers said in a study published in JAMA Oncology this month.

Why it matters: About 264,000 cases of breast cancer are diagnosed annually in women and about 2,400 in men in the U.S., according to the CDC.

What they're saying: "I have very high hopes that it is close to the final step of this vaccine potentially becoming a treatment for patients with breast cancer," said the study's lead author Mary "Nora" Disis, a professor at the University of Washington School of Medicine and director of the Cancer Vaccine Institute.

• Disis said the vaccine was found to be "very safe" in the Phase 1 trial, with the most common side effects being similar to those of the COVID vaccine: Soreness at the injection site and flu-like symptoms for a few days.

How it works: The vaccine targets a protein called human epidermal growth factor receptor 2 (HER2). HER2 is overproduced by as much as a hundredfold in as many as 30% of breast cancers, according to UW Medicine. "HER2-positive" cancers tend to be more aggressive and more likely to recur after treatment, Disis said.

• But the overproduction of HER2 may also trigger a beneficial cell-killing immune reaction in some.

• Recurrence is lower and survival rates are higher in people who have that immune response.
• To harness that reaction, Disis and her colleagues created a DNA vaccine which is absorbed by cells at the site of the injection.
• Those cells then start to produce the protein encoded in the vaccine’s DNA instructions which prompts a strong cytotoxic immune response, the study found.

What's next: Patients with HER2 breast cancer are being recruited for the Phase II clinical trial. For more information contact the patient coordinator: [email protected] or call 206-543-3829.

Listen to Disis and a patient talk about the vaccine here.