Letermovir

Letermovir (AIC246) is a novel anti-CMV compound (EC50: about 5 nM in fibroblast cells) . It targets the pUL56 subunit of the viral terminase complex. (In Vitro) :AIC246 has consistent antiviral efficacy, and there is remarkable selectivity of AIC246 for human cytomegaloviruses. AD169 mutant strains and designated rAIC246-1 and rAIC246-2 are highly resistant to Letermovir (AIC246), with EC50s of 5.6 nM, 1.24 μM, 0.37 μM, respectively. Letermovir inhibits HCMV replication through a specific antiviral mechanism that involves the viral gene product UL56. Letermovir inhibits HCMV replication in cell culture by interfering with the proper cleavage/packaging of HCMV progeny DNA. Letermovir inhibits the current gold standard GCV by more than 400-fold with respect to EC50s (mean, 4.5 nM versus 2 μM) and by more than 2,000-fold with respect to EC90 values (mean, 6.1 nM versus 14.5 μM) . Letermovir in conbination with anti-HCMV drugs causes additive antiviral effects, but there is no interaction between letermovir and anti-HIV drugs. (In Vivo) :Letermovir (10-100 mg/kg/day, p.o.) leads to a dose-dependent reduction of the HCMV titer in transplanted cells compared to that of the placebo-treated control group using the mouse xenograft model.