Breast cancer vaccine: promising early results

From Innovate magazine, fall 2016

Written by Julia Evangelou Strait

Willisam Gillanders with breast cancer vaccineA breast-cancer vaccine designed by researchers at Washington University is safe when used to treat patients with metastatic breast cancer. Preliminary evidence from a small clinical trial led by William Gillanders, MD, pictured here, also suggests the vaccine helped slow the cancer’s progression. Photo by Robert BostonAn early clinical trial of a breast-cancer vaccine developed at Washington University School of Medicine has shown promise in a small study. Researchers found that the vaccine triggered patients’ immune systems to attack tumor cells and helped slow the cancer’s progression.

The vaccine works by causing the immune system to home in on a protein called mammaglobin-A, which is found almost exclusively in breast tissue. Though researchers don’t know what role this protein plays in healthy breast tissue, they do know that breast tumors express it at abnormally high levels. The vaccine prompts certain white blood cells to seek out and destroy cells carrying the mammaglobin-A protein.

The study included 14 patients with metastatic breast cancer that expressed mammaglobin-A. Because it was a phase I trial, the study was designed to look primarily at the vaccine’s safety. Researchers found that participants experienced few side effects, reporting eight events classified as mild or moderate, including rash, tenderness at the vaccination site and mild flu-like symptoms. No severe or life-threatening side effects occurred.

Based on the results of the phase I study, researchers are now planning a larger clinical trial to test the vaccine in patients with newly diagnosed breast-cancer, who, in theory, should have more robust immune systems than patients who already have had extensive cancer therapy.

“If we give the vaccine to patients at the beginning of treatment, their immune systems should not be compromised like they are in patients with metastatic disease,” says William Gillanders, MD, a Washington University breast-cancer surgeon at Siteman Cancer Center and the leader of the phase I trial. “Now that we have good evidence that the vaccine is safe, we think testing it in newly diagnosed patients will give us a better idea of the effectiveness of the therapy.”