3,11-Difluoro-6,8,13-trimethyl-8H-quino[4,3,2-kl]acridinium Methyl Sulfate is a G-quadruplex-stabilizing telomerase inhibitor (1). Telomerase inhibitors has been implicated as potential cancer specific therapy to disrupt DNA stability in tumor cells(2). Inhibiting telomerase activity can shorten telomere length, which may result in senescence or apoptosis.