Abstract Therapeutic cancer vaccines are an attractive approach for treating malignant tumors, and successful tumor eradication depends primarily on controlling tumor immunosuppression status as well as heterogeneity of tumor cells driven by epigenetic alterations. Here we describe an effective peptide vaccination approach capable of circumventing antigenic heterogeneity by targeting multiple shared tumor antigens simultaneously in murine myeloid leukemia. Peptide-loaded dendritic cell (DC) prime and noninfectious peptide booster heterologous immunizations were assessed for the immunogenicity of polo-like kinase-1 (PLK1)-derived peptides, and targeting multiple shared tumor antigens simultaneously with PD-L1 blockade was evaluated for antitumor effects against murine myeloid leukemia. A synthetic PLK1122 (DSDFVFVVL)-based heterologous vaccination generated large numbers of long-lasting antigen-specific CD8 T-cells eliciting therapeutic effects against various established tumors. The therapeutic efficacy of single antigen-targeting PLK1122-based vaccine with sufficient endurance of PD-L1 blockade toward C1498 leukemia relied on the heterogeneous clonal levels of MHC-I and PD-L1 expression. A novel multi-peptide-based vaccination targeting PLK1 and survivin simultaneously along with PD1 blockade led to complete tumor eradication and long-term survival in mice with clonally heterologous C1498 myeloid leukemia. Our findings suggest that PLK1 could be an attractive immunotherapeutic target antigen for cancer immunotherapy, and that similar strategies would be applicable for the optimization of cancer vaccines for the treatment of numerous viral diseases and malignant tumors.