Author(s)

Maxwell Omabe¹, Shahid Ahmed², Amer Sami², Yufeng Xie³, Min Tao³, Jim Xiang^1,2*

¹Cancer Research Cluster, Saskatchewan Cancer Agency, Saskatoon, Canada.
²Department of Oncology, University of Saskatchewan, Saskatoon, Canada.
³Department of Oncology, The first Affiliated Hospital, Soo-Chow University, Suzhou, China.

Anti-human epidermal growth factor receptor-2 (HER2) immunization can be elicited by vaccination with DNA encoding the extra- or intra-cellular domain (ECD or ICD) of HER2, naked or encap-sulated in viral vectors. HER2-peptides derived from ECD or ICD of HER2, and HER2-pulsed dendritic cells (DCs) or engineered DCs expressing HER2, respectively. We performed a computer- based literature search which includes but is not limited to the following keywords: breast cancer, immunotherapy, HER2-peptide vaccine, HER2-DNA vaccine, HER-DC vaccine, HER2 vaccine, and HER2/neu, in PubMed, Medline, EMBO and Google Scholar; data from recently reported clinical trials were also included. Drawing upon this synthesis of literature, this work summarizes the de-velopment and current trend in experimental and clinical investigations in HER2-positive breast cancer using HER2-specific vaccine and immunotherapy, focusing especially on: (i) DNA-; (ii) peptide-; and (iii) DC-based vaccines. It addresses interventions that have been applied to overcome immunotolerance thereby to improve treatment outcomes. These include blocking the inhibitory cytotoxic T lymphocyte-associated protein-4 (CTLA-4), which is expressed at high levels by regulatory T (Treg) cells, or complete Treg depletion to improve T-cell activation. Moreover, modulatory interventions can provide further improvement in the efficacy of HER2-specific vaccine. The interventions include the use of immunogenic adjuvants such as cytokines interleukin-12 (IL-12), tumor necrosis factor (TNF)-α and granulocyte-macrophage colony-stimulating factor (GM-CSF), the use of Toll-like receptor (TLR) ligands and tetanus toxin’s universal epitopes such as the CD4+ help T (Th)-epitope P30, and the use of either chimeric or heterogenous xenogeneic HER2. Combining active HER2-vaccination with adoptive trastuzumab antibody immunotherapy is likely to increase the effectiveness of each approach alone. The development of effective HER2-vaccines for breast cancer remains a critical challenge. Though these novel interventions seem promising, further investigation is still needed since the results are preliminary. Furthermore, the review discusses the challenges and future perspectives in HER2-vaccine research and development.

HER2, Breast Cancer, DNA, Peptide, Dendritic Cell, Vaccine

Omabe, M. , Ahmed, S. , Sami, A. , Xie, Y. , Tao, M. and Xiang, J. (2015) HER2-Specific Vaccines for HER2-Positive Breast Cancer Immunotherapy. World Journal of Vaccines, 5, 106-128. doi: 10.4236/wjv.2015.52013.