Vaccine in Development for Early-Stage Breast Cancer

Researchers at the Moffitt Cancer Center are developing a new vaccine that will help early-stage breast cancer patients who have HER2 positive disease. The HER2 protein is overexpressed in more than 25 percent of all breast cancer tumors. Previously, the researchers found that immune cells are less able to recognize and target cancer cells that express HER2 as breast cancer progresses into a more advanced and invasive stage, suggesting stimulating the immune system to recognize and target HER2 early may be a more effective treatment option. So, they created a vaccine from dendritic immune cells that are harvested from each individual patient to help the immune system recognize the HER2 protein on breast cancer cells.

In a clinical trial that included 54 women who have HER2-expressing early-stage breast cancer, patients were injected once a week for six weeks with a dose of their personal dendritic cell vaccine, which was prepared by isolating dendritic cells from the patients’ blood and exposing them to fragments of the HER2 protein. The vaccine, which was injected into either a lymph node, the breast tumor or both sites, stimulated an immune response in the majority of patients, with approximately 80 percent experiencing a detectable immune response in their peripheral blood and/or in their sentinel lymph node where their cancer is most likely to spread first. Importantly, the immune responses among the patients were similar, regardless of the route of vaccine administration. To determine the effectiveness of the vaccine, the researchers looked at the percentage of patients who had detectable disease within surgical specimens after resection. Thirteen of the patients achieved a pathological complete response (absence of disease), and patients who had early noninvasive disease called ductal carcinoma in situ achieved a higher rate of pathological complete response than patients who had early-stage invasive disease. Additionally, patients who achieved a pathological complete response had a higher immune response within their sentinel lymph nodes.