Randomised clinical trial: anti-viral activity of ANA773, an oral inducer of endogenous interferons acting via TLR7, in chronic HCV.

BACKGROUND: The ANA773 is an oral prodrug of a small-molecule toll-like receptor (TLR)7 agonist. Preclinical and healthy volunteer clinical studies with ANA773 have demonstrated induction of endogenous interferon-α (IFN-α) of multiple subtypes, which supports the potential utility in the treatment of chronic hepatitis C virus (HCV) infection. AIM: To examine safety, tolerability, pharmacodynamics, pharmacokinetics and anti-viral activity of ANA773. METHODS: The ANA773 was investigated in a double-blind, placebo-controlled study in 34 patients chronically infected with HCV of any genotype. Patients were treatment-naïve or had relapsed following previous interferon-based treatment. This dose escalation study was composed of four dose groups (800, 1200, 1600 and 2000mg). In each group, six to eight patients received ANA773 and two received placebo. Patients were dosed with ANA773 every-other-day for either 28 days (800, 1200 or 1600mg) or 10days (2000mg). RESULTS: Mild to moderate adverse events were reported, with an increase in frequency and intensity with increasing dose. No serious AEs were reported and there were no early discontinuations. There were dose-related increases in various markers of IFN-α response. The mean maximum change in serum HCV RNA level from baseline was -0.34, -0.29, -0.40, -0.97 and -1.26log(10) in the placebo, 800, 1200, 1600 and 2000mg cohorts, respectively. At the 2000mg dose, ANA773 significantly (P=0.037) reduced serum HCV RNA levels (range: 0.14 to -3.10log(10) ). CONCLUSION: The ANA773 was generally well tolerated and resulted in a dose-related IFN-dependent response leading to a significant decrease in serum HCV RNA levels in the 2000mg dose group.

The pharmacology of endosomal TLR agonists in viral disease.

The discovery of endosomal TLRs (Toll-like receptors) and their natural ligands has accelerated efforts to exploit them for therapeutic benefit. Importantly, this was preceded by clinical exploration of agents now known to be endosomal TLR agonists. Clinical effects in viral disease have been reported with agonists of TLR3, TLR7, TLR7/8 and TLR9, and the TLR7 agonist imiquimod is marketed for topical use against warts, a papillomavirus disease. The observed pre-clinical and clinical profiles of agonists of each of these TLRs suggest induction of a multifaceted innate immune response, with biomarker signatures indicative of type 1 interferon induction. However, these agents differ in both their pharmaceutical characteristics and the cellular distribution of their target TLRs, suggesting that drugs directed to these targets will display differences in their overall pharmacological profiles.

A prokaryotic-like mode of cytoplasmic eukaryotic ribosome binding to the initiation codon during internal translation initiation of hepatitis C and classical swine fever virus RNAs.

Initiation of translation of hepatitis C virus and classical swine fever virus mRNAs results from internal ribosomal entry. We reconstituted internal ribosomal entry in vitro from purified translation components and monitored assembly of 48S ribosomal preinitiation complexes by toe-printing. Ribosomal subunits (40S) formed stable binary complexes on both mRNAs. The complex structure of these RNAs determined the correct positioning of the initiation codon in the ribosomal "P" site in binary complexes. Ribosomal binding and positioning on these mRNAs did not require the initiation factors eIF3, eIF4A, eIF4B, and eIF4F and translation of these mRNAs was not inhibited by a trans-dominant eIF4A mutant. Addition of Met-tRNAiMet, eIF2, and GTP to these binary ribosomal complexes resulted in formation of 48S preinitiation complexes. The striking similarities between this eukaryotic initiation mechanism and the mechanism of translation initiation in prokaryotes are discussed.