MK-2048S2765

MK-2048 inhibits subtype B and subtype C integrase activities with IC50 of 75 nM and 80 nM, respectively. Disintegration is prevented by high concentrations of MK-2048 to a comparable extent with both subtype B and C enzymes. Mutation at the site of R263K slightly increases integrase susceptibility to MK-2048. G118R translates into a decrease in integrase activity and confers resistance to MK-2048. ^[2] MK-2048 inhibits S217H intasome with an IC50 of 900 nM. By contrast, MK2048 remains fully active against the N224H intasome with an IC50 of 25 nM. MK2048 displays substantially lower dissociation rates compared with raltegravir, another integrase inhibitor. ^[3] The subsequent selection of E138K partially restores replication capacity to approximately 13% of wt levels and increased resistance to MK-2048 to approximately 8-fold. MK-2048 is active against viruses resistant to RAL and EVG. Exposure to MK-2048 leads to the selection of G118R as a possible novel resistance mutation after 19 weeks. Continued pressure with MK-2048 subsequently leads to an additional substitution after 29 weeks at position E138K, within the IN gene. Although the G118R mutation alone confers only slight resistance to MK-2048 but not to RAL or EVG, its presence arouses a dramatic reduction in viral replication capacity compared to wild-type NL4-3. E138K both partially restores viral replication capacity and also contributes to increased levels of resistance against MK-2048. ^[4]