NCIt definition : A synthetic lipid-conjugated, 13-mer oligonucleotide N3'-P5'-thio-phosphoramidate
with potential antineoplastic activity. Complementary to the template region of telomerase
(hTR) RNA, imetelstat acts as a competitive enzyme inhibitor that binds and blocks
the active site of the enzyme (a telomerase template antagonist), a mechanism of action
which differs from that for the antisense oligonucleotide-mediated inhibition of telomerase
activity through telomerase mRNA binding. Inhibition of telomerase activity in tumor
cells by imetelstat results in telomere shortening, which leads to cell cycle arrest
or apoptosis.;