The telomerase catalytic subunit is a widely expressed tumor-associated antigen recognized by cytotoxic T lymphocytes

The discovery of tumor-associated antigens (TAA) in certain human malignanc ies has prompted renewed efforts to develop antigen-specific immunotherapy of cancer. However, most TAA described thus far are expressed in one or a f ew tumor types, and, among patients with these types of tumors, TAA express ion is not universal. Here, we characterize the telomerase catalytic subuni t (hTERT) as a widely expressed TAA capable of triggering antitumor cytotox ic T lymphocyte (CTL) responses. More than 85% of human cancers exhibit str ong telomerase activity, but normal adult tissues, with few exceptions, do not. In a human system, CD8(+) CTL specific for an hTERT peptide and restri cted to MHC HLA-A2 lysed hTERT(+) tumors from multiple histologies. These f indings identify hTERT as a potentially important and widely applicable tar get for anticancer immunotherapeutic strategies.