MK-2048

MK-2048 is a second generation inhibitor of HIV-1 integrase with IC50 values of 0.075 μM and 0.08 μM for subtype B and subtype C integrase, respectively.
Integration of viral cDNA into the host genome is one of the definitive features of retrovirus replication. Integrase inhibitors are active against both B and non-B subtypes in therapy. Subtype C variants are responsible for approximately 50% of infections worldwide, mostly in Sub-Saharan Africa and India. After viral entry and reverse transcription, reverse-transcribed double-stranded blunt-ended DNA is incorporated into the host cell genome through two catalytic activities mediated by integrase. MK-2048 could inhibit the strand transfer process catalyzed by integrase.
The inhibition activity of MK-2048 against integrase was evaluated by means of purified recombinant subtype B and C integrase enzymes, which were obtained and amplified from viruses in long-term infected patients. Purified recombinant subtype B and C integrase enzymes were incubated with increasing concentrations of MK-2048 and corresponding templates. MK-2048 possesses inhibition activities for strand transfer against subtype B and C enzymes, whose IC50 values were 0.075 μM and 0.08 μM, respectively. Disintegration was inhibited by high concentrations of MK-2048 to a comparable extent with both subtype B and C enzymes.
Inhibition of replication by MK-2048 was also evaluated in cell culture based assays using cord blood mononuclear cells. EC50 for subtype B viruses varies from 0.0003 μM to 0.0148 μM and 0.0007 μM to 0.0033 μM for subtype C viruses.
References:
1.Bar-Magen T, Sloan R D, Faltenbacher V H, et al. Comparative biochemical analysis of HIV-1 subtype B and C integrase enzymes[J]. Retrovirology, 2009, 6(1): 103.

Identification of novel mutations responsible for resistance to MK-2048, a second-generation HIV-1 integrase inhibitor.[Pubmed:20610719]

J Virol. 2010 Sep;84(18):9210-6.

MK-2048 represents a prototype second-generation integrase strand transfer inhibitor (INSTI) developed with the goal of retaining activity against viruses containing mutations associated with resistance to first-generation INSTIs, raltegravir (RAL) and elvitegravir (EVG). Here, we report the identification of mutations (G118R and E138K) which confer resistance to MK-2048 and not to RAL or EVG. These mutations were selected in vitro and confirmed by site-specific mutagenesis. G118R, which appeared first in cell culture, conferred low levels of resistance to MK-2048. G118R also reduced viral replication capacity to approximately 1% that of the isogenic wild-type (wt) virus. The subsequent selection of E138K partially restored replication capacity to approximately 13% of wt levels and increased resistance to MK-2048 to approximately 8-fold. Viruses containing G118R and E138K remained largely susceptible to both RAL and EVG, suggesting a unique interaction between this second-generation INSTI and the enzyme may be defined by these residues as a potential basis for the increased intrinsic affinity and longer "off" rate of MK-2048. In silico structural analysis suggests that the introduction of a positively charged arginine at position 118, near the catalytic amino acid 116, might decrease Mg(2+) binding, compromising enzyme function and thus leading to the significant reduction in both integration and viral replication capacity observed with these mutations.