About >85% of all human cancers, including breast cancer, express telomerase (hTERT) activity. Targeting hTERT immunologically may also minimize immune escape due to antigen loss because mutation or deletion of hTERT may be incompatible with sustained tumor growth. hTERT Multi-Peptide Vaccine is made up of 1540 hTERT peptide and cryptic peptides selected for "low-affinity" binding to HLA-A2 in order to increase the likelihood that the host immune system would ignore them, and then they have been modified by changing the first amino acid of the peptides to tyrosine in order to increase HLA - A2 affinity. The two "heteroclitic" peptides are R572Y (YLFFYRKSV) and D988Y (YLQVNSLQTV), which bind HLA-A2 with high avidity and elicit specific CTL (cytotoxic T lymphocyte) responses using healthy donor mononuclear cells in vitro. In addition, in mouse models, these peptide vaccines elicit lytic CTL responses which are protective against tumor challenges using a TERT-expressing murine tumor.