TERT and cancer: Several telomere-targeting agents have been developed, including antisense oligonucleotides that block the expression of TERT, the enzyme responsible for telomerase activity; G-quadruplex stabilizers that prevent telomerase from elongating telomeres; small-molecule inhibitors that inhibit telomerase activity or prevent its recruitment to telomeres; and immunotherapies that trigger immune responses against cancer cells by inducing telomere stress.