Irine is achieved by a combination of at least three mutations
Irine is achieved by a combination of at least three mutations, including V90I, A98G, L100I, K101E/P, V106I, V179D/F, Y181C/I/V and G190A/S [16]. There has been considerable work showing how the DAPY class of NNRTIs bind and inhibit RT [3,10,17-20]. Several groups have designed derivatives of these compounds [20,21]. However, much of the SAR surrounding this class of agents is found primarily in the patent literature. The activities of a number of key structural analogues of both rilpivirine (1) and etravirine (2) against NNRTIresistant mutants have not been reported, nor have the interactions of these analogs with HIV-1 RT been evaluated in structural studies. Such information would provide a deeper understanding of how these molecules inhibit WT and drug-resistant RTs and how they can be engineered to enhance their activity against viruses that carry resistance mutations. In addition, novel analogues that select for different patterns of mutations than rilpivirine or etravirine could be used as second-line treatment in patients experiencing VF with either of these drugs, or possibly, in combination with existing drugs. The difference in mutation profile selected by these drugs, despite their structural similarities, suggests that subtle changes can significantly affect the mechanism by which resistance arises. To pursue the goal of identifying analogues that will select novel resistance mutations, we focused our efforts on compounds with specific alterations of the pyrimidine moiety and the 4-aminobenzonitrile moiety of rilpivirine (1) (Figure 2). We were motivated to alter only these structural motifs because the (E)-3-(4-amino-3,5-dimethylphenyl)acrylonitrile ring system has been shown to be an important motif for rilpivirine binding within the induced NNRTI-binding pocket [19].Results and discussionInhibitory activity of pyrimidine-based analoguesWe examined the effects of rilpivirine and the analogues on HIV-1 replication using a previously described assay and report the concentrations at which luciferase reporter activity was reduced by half relative to uninhibited controls (EC50) with standard deviations in parentheses. In the assay, viral vectors that replicate using WT HIV reverse transcriptase or one of several mutants (L100I, K103N, V106A, E138K, Y181C, Y188L, H221Y and the double mutant K103N/Y181C) were used to infect cells in a single round assay. These mutants were chosen either because they are known NNRTI resistance mutations (L100I, K103N, Y181C, and the K103N/Y181C double mutant), they were selected GW9662MedChemExpress GW9662 inJohnson et al. PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27484364 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28128382 Retrovirology 2012, 9:99 http://www.retrovirology.com/content/9/1/Page 3 ofFigure 2 Chemical structures of rilpivirine analogues. Analogues differed from rilpivirine (1, boxed) by the addition of an exocyclic moiety to the pyrimidine ring in either of its `flipped’ conformations (6?), the replacement of the pyrimidine ring with a 2,6-purine ring system in `flipped’ conformations with or without a protecting group (10?3), replacing the 4-benzonitrile moiety in addition to replacing the pyrimidine ring with a 2,6-purine (14?5), or replacing the pyrimidine ring with a 2,9-purine ring system (26, 27). Differences between each analogue and rilpivirine are indicated in red.patients in rilpivirine clinical trials (E138K and H221Y), or they are positioned to make significant Van der Waals contacts with rilpivirine (V106A and Y188L). All compounds were initially screened against a panel that included at least one.