Human telomerase reverse transcriptase (hTERT) represents a universal tumor-associated antigen to activate specific immune response in cancer immune therapy. Peptides derived from hTERT are presented by major histocompatibility complex (MHC) class I alleles to T lymphocytes, and CD8+ cytotoxic T lymphocytes (CTLs) specific for the hTERT-derived antigenic epitopes lyse hTERT-positive tumors from multiple histologies. These findings identify hTERT as an important tumor antigen widely applicable for anti-cancer immunotherapeutic strategies. The hTERT antigen-specific immunotherapy involves both active vaccination and adoptive immunotherapy approaches. Most importantly, the anti-tumor immune responses have been observed in the absence of toxicity, underlying the ongoing endeavors to develop immunotherapy directed against hTERT antigen. This chapter discusses most promising results and the approaches for investigation to target hTERT peptides as tumor antigens.
