Cancer Therapy: Preclinical Universal Cancer Peptide-Based Therapeutic Vaccine Breaks Tolerance against Telomerase and Eradicates Established Tumor

Purpose: To evaluate CD4þ helper functions and antitumor effect of promiscuous universal cancer peptides (UCP) derived from telomerase reverse transcriptase (TERT). Experimental Design: To evaluate the widespread immunogenicity of UCPs in humans, spontaneous T-cell responses against UCPs were measured in various types of cancers using T-cell proliferation and ELISPOT assays. The humanized HLA-DRB1 0101/HLA-A 0201 transgenic mice were used to study the CD4þ helper effects of UCPs on antitumor CTL responses. UCP-based antitumor therapeutic vaccine was evaluated using HLA-A 0201–positive B16 melanoma that express TERT. Results: The presence of a high number of UCP-specific CD4þ T cells was found in the blood of patients with various types of cancer. These UCP-specific T cellsmainly produce IFN-g and TNF-a. InHLA transgenic mice, UCP vaccinations induced high avidity CD4þ TH1 cells and activated dendritic cells that produced interleukin-12. UCP-based vaccination breaks self-tolerance against TERT and enhances primary and memory CTL responses. Furthermore, the use of UCP strongly improves the efficacy of therapeutic vaccination against established B16-HLA-A 0201 melanoma and promotes tumor infiltration by TERTspecific CD8þ T cells. Conclusions: Our results showed that UCP-based vaccinations strongly stimulate antitumor immune responses and could be used to design efficient immunotherapies in multiple types of cancers. Clin Cancer Res; 18(22); 6284–95. 2012 AACR.