Cancer Vaccines in Advanced Breast Cancer: A Literature Review of Efficacy, Challenges, and Future Directions

Advanced breast cancer continues to pose significant therapeutic challenges despite advances in systemic therapies. Cancer vaccines represent a promising immunotherapeutic strategy aimed at inducing tumor-specific immune responses. This review synthesizes clinical evidence on therapeutic cancer vaccines in advanced breast cancer, evaluating diverse platforms including peptide, DNA, viral vector, dendritic cell, whole-cell, and ganglioside-based vaccines. While vaccines consistently demonstrate safety and immunogenicity across trials, clinical efficacy remains modest and heterogeneous, with objective responses largely confined to small patient subsets. Key challenges include tumor heterogeneity, immunosuppressive microenvironments, and the lack of large randomized phase III trials. Emerging strategies emphasize multiepitope and personalized neoantigen vaccines, rational combinations with checkpoint inhibitors or targeted therapies, and deployment in minimal residual or oligometastatic disease states. Future progress will depend on biomarker-driven trial designs and integration of vaccines into multimodal treatment paradigms to achieve durable clinical benefit.