**14.4 Combination therapy: PD1/PD-L1 antibody and cancer vaccine**

Cancer vaccines are a novel approach to cancer immunotherapy. These vaccines promote T cell priming and activation and strengthen immune recognition of cancer cells by presenting breast cancer peptides to T cells. Monovalent vaccines, which provide a single tumor-associated antigen (TAA) target for the immune system, and polyvalent peptide vaccines, which provide several TAA targets, are two types of cancer vaccines. Low response rates have hampered the application of peptide vaccines for the treatment of patients with metastatic cancer; although, making use of a multi-peptide vaccine strategy, the response rate in various cancer types has improved to 9.9% [100, 101]. Furthermore, cancer vaccines in conjunction with immune checkpoint inhibitors can improve the vaccine's anti-tumor immune response. In advanced TNBC, a few ongoing studies are looking into the effectiveness of cancer vaccines in conjunction with pembrolizumab, making use of either the multipeptide vaccine PVX-410 (NCT03362060) or specific vaccines which target p53 (NCT02432963) or WT1 (NCT03761914). Furthermore, few clinical trials have been conducted to investigate the efficacy of durvalumab in combination with the multipeptide vaccine PVX-410 (NCT02826434) or with a neoantigen vaccine (NCT03606967, NCT03199040), as well as atezolizumab in combination with a neoantigen vaccine (NCT03289962) (**Table 6**).
