The ideal cancer treatment would specifically target cancer cells yet have 
minimal or no adverse effects on normal somatic cells. Telomerase, the 
ribonucleoprotein reverse transcriptase that maintains the ends of human 
chromosome, is an attractive cancer therapeutic target for exactly this reason 
[1]. Telomerase is expressed in more than 85% of cancer cells, making it a 
nearly universal cancer marker, while the majority of normal somatic cells are 
telomerase negative. Telomerase activity confers limitless replicative potential 
to cancer cells, a hallmark of cancer which must be attained for the continued 
growth that characterizes almost all advanced neoplasms [2]. In this review we 
will summarize the role of telomeres and telomerase in cancer cells, and how 
properties of telomerase are being exploited to create targeted cancer therapies 
including telomerase inhibitors, telomerase-targeted immunotherapies and 
telomerase-driven virotherapies. A frank and balanced assessment of the current 
state of telomerase inhibitors with caveats and potential limitations will be 
included.