Tetrahydrocarbazole amides with potent activity against human papillomaviruses.

Synthesis of a series of tetrahydrocarbazole amides with potent activity against human papillomaviruses is described. Synthetic approaches allowing for variation of the substitution pattern of the tetrahydrocarbazole and the amide are outlined and resulting changes in antiviral activity and certain developability parameters are highlighted. Several compounds with in vitro antiviral activity (W12 antiviral assay) in the single digit nanomolar range were identified and N-[(1R)-6-chloro-2,3,4,9-tetrahydro-1H-carbazol-1-yl]-2-pyridinecarboxamide was selected for further evaluation.

GSK983: a novel compound with broad-spectrum antiviral activity.

GSK983, a novel tetrahydrocarbazole, inhibits the replication of a variety of unrelated viruses in vitro with EC(50) values of 5-20 nM. Both replication of the adenovirus Ad-5 and the polyoma virus SV-40, and episomal maintenance of human papillomaviruses (HPV) and Epstein-Barr virus (EBV) are susceptible to GSK983. The compound does not inhibit all viruses; herpes simplex virus (HSV-1), human immunodeficiency virus (HIV), and lytic replication of EBV were not susceptible at concentrations below 1 microM. GSK983 does inhibit the growth of cell lines immortalized by HTLV-1, EBV, HPV, SV40 and Ad-5, with EC(50) values in the range of 10-40 nM. Depending on the cell line, the compound induces either apoptosis or cytostasis at concentrations over 20 nM. GSK983 also inhibits cell lines immortalized by non-viral mechanisms, but has little effect on primary cells. The CC(50) values for keratinocytes, fibroblasts, lymphocytes, endothelial, and bone marrow progenitor cells are all above 10 microM. The pattern of inhibition, which includes diverse viruses as well as growth of immortalized cells of varied origins, suggests the target is a host cell protein, rather than a viral protein. Preliminary mechanism studies indicate that GSK983 acts by inducing a subset of interferon-stimulated genes.

Synthesis of C-6 substituted pyrazolo[1,5-a]pyridines with potent activity against herpesviruses.

A novel series of potent C-6 substituted pyrazolo[1,5-a]pyridine inhibitors of herpes simplex viruses has been identified. A synthetic methodology was developed involving functionalization of a C-6 trifluoromethyl pyrazolo[1,5-a]pyridine to allow facile access to a diverse set of analogues from common late stage intermediates. The expansion of the SAR of this series at the 6 position allows for modifications to developability parameters such as clogP, while maintaining potency comparable to acyclovir.

Antiviral activity of GW678248, a novel benzophenone nonnucleoside reverse transcriptase inhibitor.

The compound GW678248 is a novel benzophenone nonnucleoside reverse transcriptase inhibitor (NNRTI). Preclinical assessment of GW678248 indicates that this compound potently inhibits wild-type (WT) and mutant human immunodeficiency virus type 1 (HIV-1) reverse transcriptase in biochemical assays, with 50% inhibitory concentrations (IC(50)s) between 0.8 and 6.8 nM. In HeLa CD4 MAGI cell culture virus replication assays, GW678248 has an IC(50) of < or =21 nM against HIV-1 isogenic strains with single or double mutations known to be associated with NNRTI resistance, including L100I, K101E, K103N, V106A/I/M, V108I, E138K, Y181C, Y188C, Y188L, G190A/E, P225H, and P236L and various combinations. An IC(50) of 86 nM was obtained with a mutant virus having V106I, E138K, and P236L mutations that resulted from serial passage of WT virus in the presence of GW678248. The presence of 45 mg/ml human serum albumin plus 1 mg/ml alpha-1 acid glycoprotein increased the IC(50) approximately sevenfold. Cytotoxicity studies with GW678248 indicate that the 50% cytotoxicity concentration is greater than the level of compound solubility and provides a selectivity index of >2,500-fold for WT, Y181C, or K103N HIV-1. This compound exhibits excellent preclinical antiviral properties and, as a prodrug designated GW695634, is being developed as a new generation of NNRTI for the treatment of HIV-1 in combination with other antiretroviral agents.

Synthesis of novel substituted 2-phenylpyrazolopyridines with potent activity against herpesviruses.

Herpesviruses are a significant source of human disease; amongst these herpes simplex virus 1 (HSV-1) and HSV-2 are very prevalent and cause recurrent infections. We recently identified a pyrazolo[1,5-a]pyridine scaffold that showed promising activity against HSV-1 and HSV-2 in Vero cell antiviral assays. Here, we describe the synthesis and anti-herpetic activity of several 3-pyrimidinyl-2-phenylpyrazolo[1,5-a]pyridines with differing 2-phenyl substitution patterns. Approaches to rapidly access a number of analogs with different 2-phenyl substitution patterns are outlined. Several of the compounds described have comparable activity to acyclovir against HSV-1 and HSV-2.

Pyrazolopyridine antiherpetics: SAR of C2' and C7 amine substituents.

A novel series of potent pyrazolo[1,5-a]pyridine inhibitors of herpes simplex virus 1 replication have been identified. Several complimentary synthetic methods were developed to allow facile access to a diverse set of analogs from common late stage intermediates. Detailed examination of the amine substituents at the C2' position of the pyrimidine and C7 position of the core pyrazolopyridine is described. The antiviral data suggests that non-polar amines are preferred for optimal activity. Additionally, the 2' position has been shown to require an NH group to retain activity levels similar to that of the gold standard acyclovir.

Efficacy of famciclovir in the treatment of lamivudine resistance related to an atypical hepatitis B virus mutant.

Reactivation of chronic hepatitis B virus (HBV) infection is a major cause of morbidity and mortality after renal transplantation. Although lamivudine is an effective treatment for chronic hepatitis B, the development of drug resistance due to mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) motif is a major concern, especially in immunosuppressed patients who require prolonged therapy. Treatment with famciclovir has not been effective in the majority of patients who developed lamivudine resistance due to methionine-to-valine mutation at position 550, because this mutation has been uniformly associated with leucine-to-methionine mutation at position 526, a mutation that is associated with resistance to famciclovir. We describe a renal transplant recipient with an uncommon lamivudine-resistant HBV variant, in which methionine-to-valine/isoleucine mutation at position 550 was associated with wild-type sequence at position 526. The severe hepatitic flare consequent to the lamivudine resistance in this patient was successfully treated with famciclovir, indicating that both M550V and M550I mutants with preserved wild-type sequence at position 526 of HBV reverse transcriptase are susceptible to famciclovir. Our experience shows that famciclovir can be useful in selected patients with otherwise potentially fatal hepatitic flares related to lamivudine resistance, and that analysis of mutations in the HBV variant can be helpful in the choice of antiviral therapy.