Anti-HER2 Dendritic Vaccine Showing Promise in Early Breast Cancer Patients

An anti-HER2 dendritic vaccination may be a safe and immunogenic treatment to induce tumor-specific T-cell responses in HER2-positive, early-stage breast cancer patients, according to a new study published in the December 13, 2016 online issue of Clinical Cancer Research.

The researchers reported that the immune and clinical responses were similar independent of vaccination route. They also found evidence to suggest that immune responses in the sentinel lymph nodes may be more reflective of antitumor activity than immune responses in the peripheral blood.

The HER2 protein is overexpressed in 20% to 25% of all breast cancer tumors and is associated with aggressive disease and poor prognosis. Researchers at the Moffitt Cancer Center have previously shown 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.

In their current investigation, they compared immune and clinical responses to vaccination via intralesional (IL), intranodal (IN), or both intralesional and intranodal (ILN) injection. The trial included 54 HER2-positive patients (42 pure ductal carcinoma in situ [DCIS] cases and 12 early-stage invasive breast cancer [IBC] cases).

The study showed that vaccination at all injection routes was well-tolerated. There was no significant difference in immune response rates by vaccination route (IL 84.2% vs IN 89.5% vs ILN 66.7%). The pathologic complete response (pCR) rate was found to be significantly higher in DCIS patients (28.6%) compared with IBC patients (8.3%). Interestingly, the 12 DCIS patients who achieved pCR and the 30 who did not achieve pCR had similar peripheral blood anti-HER2 immune responses.

With this protocol, patients were injected with a dose of their personal dendritic cell vaccine once a week for 6 weeks. “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,” said Brian Czerniecki, MD, PhD, Chair of the Department of Breast Oncology at Moffitt Cancer Center, Tampa, Fla.

The researchers report that the dendritic cell vaccines were well-tolerated and patients only experienced low-grade toxicities. The most common adverse events were fatigue, injection site reactions, and chills. 

The study demonstrated that the vaccine was able to stimulate an immune response in the majority of the patients. Approximately 80% of evaluable patients had a detectable immune response in their peripheral blood and/or in their sentinel lymph node. In addition, the immune responses among the patients were similar, regardless of the route of vaccine administration.