The discovery of IDX21437: Design, synthesis and antiviral evaluation of 2'-α-chloro-2'-ß-C-methyl branched uridine pronucleotides as potent liver-targeted HCV polymerase inhibitors.

Herein we describe the discovery of IDX21437 35b, a novel RPd-aminoacid-based phosphoramidate prodrug of 2'-α-chloro-2'-ß-C-methyluridine monophosphate. Its corresponding triphosphate 6 is a potent inhibitor of the HCV NS5B RNA-dependent RNA polymerase (RdRp). Despite showing very weak activity in the in vitro Huh-7 cell based HCV replicon assay, 35b demonstrated high levels of active triphosphate 6 in mouse liver and human hepatocytes. A biochemical study revealed that the metabolism of 35b was mainly attributed to carboxyesterase 1 (CES1), an enzyme which is underexpressed in HCV Huh-7-derived replicon cells. Furthermore, due to its metabolic activation, 35b was efficiently processed in liver cells compared to other cell types, including human cardiomyocytes. The selected RP diastereoisomeric configuration of 35b was assigned by X-ray structural determination. 35b is currently in Phase II clinical trials for the treatment of HCV infection.

Synthesis and antiviral evaluation of a novel series of homoserine-based inhibitors of the hepatitis C virus NS3/4A serine protease.

We disclose here the synthesis of a series of macrocyclic HCV protease inhibitors, where the homoserine linked together the quinoline P2' motif and the macrocyclic moiety. These compounds exhibit potent inhibitory activity against HCV NS3/4A protease and replicon cell based assay. Their enzymatic and antiviral activities are modulated by substitutions on the quinoline P2' at position 8 by methyl and halogens and by small heterocycles at position 2. The in vitro structure activity relationship (SAR) studies and in vivo pharmacokinetic (PK) evaluations of selected compounds are described herein.

Discovery and structural diversity of the hepatitis C virus NS3/4A serine protease inhibitor series leading to clinical candidate IDX320.

Exploration of the P2 region by mimicking the proline motif found in BILN2061 resulted in the discovery of two series of potent HCV NS3/4A protease inhibitors. X-ray crystal structure of the ligand in contact with the NS3/4A protein and modulation of the quinoline heterocyclic region by structure based design and modeling allowed for the optimization of enzyme potency and cellular activity. This research led to the selection of clinical candidate IDX320 having good genotype coverage and pharmacokinetic properties in various species.

Structure-based design of a novel series of azetidine inhibitors of the hepatitis C virus NS3/4A serine protease.

Structural homology between thrombin inhibitors and the early tetrapeptide HCV protease inhibitor led to the bioisosteric replacement of the P2 proline by a 2,4-disubstituted azetidine within the macrocyclic ß-strand mimic. Molecular modeling guided the design of the series. This approach was validated by the excellent activity and selectivity in biochemical and cell based assays of this novel series and confirmed by the co-crystal structure of the inhibitor with the NS3/4A protein (PDB code: 4TYD).

A familial case of Keratitis-Ichthyosis-Deafness (KID) syndrome with the GJB2 mutation G45E.

Keratitis-Ichthyosis-Deafness (KID) syndrome (OMIM 148210) is a congenital ectodermal defect. KID consists of an atypical ichthyosiform erythroderma associated with congenital sensorineural deafness. A rare form of the KID syndrome is a fatal course in the first year of life due to severe skin lesion infections and septicaemia. KID appears to be genetically heterogeneous and may be caused by mutations in connexin 26 or connexin 30 genes. GJB2 mutations in the connexin 26 gene are the main cause of the disease. Most of the cases caused by GJB2 mutations are sporadic, but dominant transmission has also been described. To date, the rare lethal form of the disease has been only observed in two Caucasian sporadic patients with the GJB2 mutation, with the p.Gly45Glu (G45E) arising de novo. We have reported an African family with dizygotic twins suffering from a lethal form of KID. The dizygosity of the twins was confirmed by microsatellite markers. The two patients were heterozygous for the G45E mutation of GJB2, whereas the mutation was not detected in the two parents. The unusual transmission of the disease observed in this family could be explained by the occurrence of a somatic or more probably a germinal mosaic in one of the parents.

Discovery of the Aryl-phospho-indole IDX899, a Highly Potent Anti-HIV Non-nucleoside Reverse Transcriptase Inhibitor.

Here, we describe the design, synthesis, biological evaluation, and identification of a clinical candidate non-nucleoside reverse transcriptase inhibitors (NNRTIs) with a novel aryl-phospho-indole (APhI) scaffold. NNRTIs are recommended components of highly active antiretroviral therapy (HAART) for the treatment of HIV-1. Since a major problem associated with NNRTI treatment is the emergence of drug resistant virus, this work focused on optimization of the APhI against clinically relevant HIV-1 Y181C and K103N mutants and the Y181C/K103N double mutant. Optimization of the phosphinate aryl substituent led to the discovery of the 3-Me,5-acrylonitrile-phenyl analogue RP-13s (IDX899) having an EC50 of 11 nM against the Y181C/K103N double mutant.

Topical nonnucleoside reverse transcriptase inhibitor MC 1220 partially prevents vaginal RT-SHIV infection of macaques.

The availability of an effective vaginal microbicide would be a major step toward containment of HIV transmission as well as allowing women self-protection against HIV infection. Here we evaluated the efficacy of vaginal application of the potent nonnucleoside reverse transcriptase inhibitor (NNRTI) MC 1220 against vaginal challenge of macaques with RT-SHIV, a chimeric simian immunodeficiency virus (SIV) containing the reverse transcriptase (RT) gene of HIV-1. Challenge infection of monkeys with RT-SHIV currently represents the only nonhuman primate model available to test the anti-HIV-1 effects of NNRTIs. Two different gel formulations containing different MC 1220 concentrations were evaluated for efficacy in female rhesus macaques exposed to RT-SHIV. Five groups of five animals each were treated with two different gel compositions containing no drug, 0.1% or 0.5% MC 1220, followed by vaginal RT-SHIV challenge 30 min later. One animal in each group treated with the low concentration of MC 1220 as well as one control animal remained uninfected after vaginal challenge. By contrast, three of the animals receiving 0.5% MC 1220 remained uninfected, suggesting a threshold of the drug. Despite being negative for plasma viral RNA and absence of seroconversion, almost all uninfected animals exhibited SIV-specific T cells, either in the periphery or in lymph nodes draining the portal of virus entry. Our results make MC 1220 a promising compound for further development as a topical microbicide and warrant additional testing with improved formulation, long-lasting vaginal delivery systems, or even combinations with other inhibitors.