Several therapies targeting this well-described telomerase-based pathway are in the advanced stages of clinical development, but as with any cancer therapy there is the potential for development of resistance against telomerase-based strategies to defeat cancer.
Studies using mice and human cancer cell lines have demonstrated that cancer can overcome the loss of telomerase by using a telomerase-independent mechanism called alternative lengthening of telomeres.
It is therefore plausible that telomerase-dependent cancer treatments will introduce selective pressures in human tumors to activate the ALT pathway and/or select for cells already using ALT within the tumor.
Clearly, targeting ALT is a very attractive strategy in the development of novel cancer therapies.
The level of C-circles in cancer cells accurately reflects the level of ALT activity, and this biomarker can be found in the blood of patients who have bone cancers positive for ALT activity.
Based on the conservative estimate that 10 percent of cancers employ an ALT strategy to achieve cellular immortality, there are about 1.4 million new cases and 820,000 deaths globally due to ALT cancers every year.
Please help us control ALT and thus delete the burden of cancer from society at large.