Breast Cancer Immunotherapy Vaccine Shows Promise

A personalized vaccine may effectively treat HER2-postive breast cancer.

Results from a new study suggest that a new immunotherapy vaccine could be used to treat patients with early HER2-positive breast cancer.

Approximately 25% of patients diagnosed with breast cancer have high expression of the HER2 protein, which is linked to aggressive disease and poor prognosis, according to a study published by Clinical Cancer Research. This subtype of breast cancer is likely to metastasize, and recur even after treatment.

This team of researchers previously discovered that immune cells are less likely to identify cancer cells that express HER2 as pathogens during disease progression, which means that cancer cells can easily evade the immune system and spread. These findings suggest that immunotherapy techniques that allow the immune system to recognize cancer cells earlier may be an effective treatment.

Included in the study were 54 women with early-stage HER2-positive breast cancer. The vaccine was created by harvesting dendritic immune cells from the blood of each patient, and then exposing those cells to fragments of HER2.

The patients were then injected with their personalized vaccine once per week for 6 weeks. The vaccine was administered into a lymph node, the tumor, or into both sites, according to the study.

The researchers discovered that the vaccines were generally well-tolerated by patients, with only low-grade toxicities observed. Common adverse events experienced by patients included fatigue, injection site reactions, and chills.

Approximately 80% of patients had an immune response in their peripheral blood or in their sentinel lymph node, which is where the cancer is likely to spread, according to the study. The researchers noted that a positive response was seen among patients regardless of where the vaccine was administered.

The investigators determined the efficacy of the vaccine by assessing how many patients had detectable disease in resected tumor samples. Patients whose tumors were disease-free were classified as having a pathological complete response, and were observed to have a higher response in their sentinel lymph nodes.

Patients with ductal carcinoma in situ (DCIS) had an increased rate of complete pathological response compared with patients who had early-stage invasive disease, according to the study.

Other studies have shown that personalized immunotherapy vaccines were also particularly effective against metastatic melanoma, with patients surviving at least 8 years.

It is clear that the future of cancer research and treatments are heading in the direction of immunotherapy-based care. These recent findings suggest that patients with early breast cancer could be treated with a vaccine that elicits mild, if any, adverse effects.

“These results suggest that vaccines are more effective in DCIS, thereby warranting further evaluation in DCIS or other minimal disease settings, and the local regional sentinel lymph node may serve as a more meaningful immunologic endpoint,” concluded lead researcher Brian J. Czerniecki, MD, PhD.