Structure-Based Design, Synthesis, and Biological Evaluation of Irreversible Human Rhinovirus 3C Protease Inhibitors. 1. Michael Acceptor Structure−Activity Studies

Dragovich, Peter S.; Webber, S. E.; Babine, Robert E.; Fuhrman, Shella A.; Patick, Amy K.; Matthews, David A.; Lee, Caroline A.; Reich, Siegfried; Prins, Thomas J.; Marakovits, Joseph; Littlefield, Ethel S.; Zhou, Ru; Tikhe, Jayashree; Ford, Clifford E.; Wallace, Michael B.; Meador, James W.; Ferre, Rose Ann; Brown, Edward L.; Binford, Susan; Harr, James E. V.; DeLisle, Dorothy M.; Worland, Stephen T.

doi:10.1021/jm980068d

Cited by 99 publications

(116 citation statements)

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“…A transa-b-unsaturated ethylester incorporated into a benzyloxycarbonyl-protected tripeptide showed potent irreversible antiviral activity against three HRV serotypes in cell culture (Table II, compound VII). 319 Since moderate activity, no toxicity to the limit of its solubility and no inactivation by short exposure to dithiothreitol (DTT) were seen with this compound, variations based on an extensive structure-activity study were set up to enhance the activity of the Michael acceptors. 319 Related a-b-unsaturated carboxylic acids were poor 3C pro inhibitors and did not exhibit antiviral activity against the highest concentration examined (100 mM).…”

Section: Michael Acceptor-containingmentioning

confidence: 99%

Selective inhibitors of picornavirus replication

Palma

Vliegen

Clercq

et al. 2008

Medicinal Research Reviews

232

217

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Picornaviruses cover a large family of pathogens that have a major impact on human but also on veterinary health. Although most infections in man subside mildly or asymptomatically, picornaviruses can also be responsible for severe, potentially life-threatening disease. To date, no therapy has been approved for the treatment of picornavirus infections. However, efforts to develop an antiviral that is effective in treating picornavirus-associated diseases are ongoing. In 2007, Schering-Plough, under license of ViroPharma, completed a phase II clinical trial with Pleconaril, a drug that was originally rejected by the FDA after a New Drug Application in 2001. Rupintrivir, a rhinovirus protease inhibitor developed at Pfizer, reached clinical trials but was recently halted from further development. Finally, Biota's HRV drug BTA-798 is scheduled for phase II trials in 2008. Several key steps in the picornaviral replication cycle, involving structural as well as non-structural proteins, have been identified as valuable targets for inhibition. The current review aims to highlight the most important developments during the past decades in the search for antivirals against picornaviruses.

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Section: Michael Acceptor-containingmentioning

confidence: 99%

Selective inhibitors of picornavirus replication

Palma

Vliegen

Clercq

et al. 2008

Medicinal Research Reviews

232

217

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“…Peptidomimetics with Michael acceptor warheads permanently disable the protease by covalent binding to its catalytic site (12,13). The peptidomimetic rupintrivir (Pfizer AG7088; Fig.…”

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confidence: 99%

The Enterovirus 3C Protease Inhibitor SG85 Efficiently Blocks Rhinovirus Replication and Is Not Cross-Resistant with Rupintrivir

Lacroix

George

Leyssen

et al. 2015

Antimicrob Agents Chemother

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The novel enterovirus protease inhibitor (PI) SG85 effectively inhibits the in vitro replication of 14 rhinoviruses representative of species A and B (median 50% effective concentration, 0.04 M). A low-level SG85-resistant variant was selected that carried amino acid substitutions S127G and T143A in the 3C protease. Both substitutions are required for low-level resistance to SG85, as demonstrated by reverse genetics. Interestingly, there is no cross-resistance to SG85 and rupintrivir (another PI); a structural explanation is provided for this observation. R hinoviruses (RV) are nonenveloped, positive-sense, singlestranded RNA viruses that belong to the family of Picornaviridae, genus Enterovirus (1). Currently, more than 150 RV have been identified, which genotypically group into RV-A, RV-B, and RV-C (2). RV infections not only cause common colds but may also trigger exacerbations of asthma and chronic obstructive pulmonary disease (COPD) (3-5). Because of the high (and still rising) number of variants, development of a vaccine will be hard to achieve. Therefore, treatment with antivirals is a more realistic strategy to reduce the burden of these infections. An RV inhibitor, in particular, is needed for the prophylaxis and treatment of RVinduced exacerbations of asthma and COPD (6).The RV 3C protease (3C pro ) is a promising target for drug development efforts because of the high level of conservation in its substrate-binding site, its role as an indispensable enzyme for virus replication, and its unique cleavage specificity (after Gln), which has not been observed in any other known host cell protease (7-11). Peptidomimetics with Michael acceptor warheads permanently disable the protease by covalent binding to its catalytic site (12, 13). The peptidomimetic rupintrivir (Pfizer AG7088; Fig. 1) effectively inhibits RV and enterovirus replication in vitro but largely failed to fulfill its promise in clinical trials (14-17).Comparison of the known crystal structures of enterovirus 3C pro s revealed that the enterovirus 68 (EV68) 3C pro can be considered an intermediate between the proteases of RV02 and poliovirus (18). Therefore, it was selected for the design of broadspectrum enterovirus 3C pro inhibitors, yielding SG85, a peptidic ␣,␤-unsaturated ethyl ester with Michael acceptor properties, as the most promising candidate. SG85 is an efficient inhibitor of EV68 3Cpro and inhibits the replication of enteroviruses in cellbased assays (18,19).We demonstrate here that SG85 effectively inhibits the replication (in multicycle virus-cell-based cytopathic effect [CPE] reduction assays [20]) of 14 RV serotypes that are representative of RV-A and -B (Table 1). Median 50% effective concentrations (EC 50 s) of 0.04 Ϯ 0.02 M and 0.02 Ϯ 0.01 M were obtained against RV-A and RV-B, respectively. The 3C pro inhibitor rupintrivir (Axon Medchem, The Netherlands) was, on average, 4-fold more active (Table 1), but this varied with the type (e.g., equipotent activity against RV63 and 14-fold more potent against RV02). Akin to rupint...

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“…DNA sequence comparisons among numerous HRV serotypes and several related picornaviruses have demonstrated a significant degree of homology among amino acid residues involved in key 3C protease inhibitor-binding interactions, providing an additional rationale for targeting research activities (3,20,22). Early drug discovery efforts led to the identification of rupintrivir, an intranasally administered, irreversible inhibitor of HRV 3C protease that has demonstrated broad-spectrum, potent in vitro antiviral activity against multiple HRV serotypes, HRV clinical isolates, and related picornaviruses (8,9,14,20,24,33,34). Proof of concept for the mechanism of 3C protease inhibition was shown in a recent study in which rupintrivir moderated the severity of illness and reduced viral load in human subjects following experimental HRV infection (13).…”

mentioning

confidence: 99%

In Vitro Antiviral Activity and Single-Dose Pharmacokinetics in Humans of a Novel, Orally Bioavailable Inhibitor of Human Rhinovirus 3C Protease

Patick

Maldonado

Binford

et al. 2005

Antimicrob Agents Chemother

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121

107

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(E)-(S)-4-((S)-2-{3-[(5-methyl-isoxazole-3-carbonyl)-amino]-2-oxo-2H-pyridin-1-yl}-pent-4-ynoylamino)-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester (Compound 1) is a novel, irreversible inhibitor of human rhinovirus (HRV) 3C protease {inactivation rate constant (K obs /[I]) of 223,000 M؊1 s ؊1 }. In cell-based assays, Compound 1 was active against all HRV serotypes (35 of 35), HRV clinical isolates (5 of 5), and related picornaviruses (8 of 8) tested with mean 50% effective concentration (EC 50 ) values of 50 nM (range, 14 to 122 nM), 77 nM (range, 72 to 89 nM), and 75 nM (range, 7 to 249 nM), respectively. Compound 1 inhibited HRV 3C-mediated polyprotein processing in infected cells in a concentration-dependent manner, providing direct confirmation that the cell-based antiviral activity is due to inhibition of 3C protease. In vitro and in vivo nonclinical safety studies showed Compound 1 to be without adverse effects at maximum achievable doses. Single oral doses of Compound 1 up to 2,000 mg in healthy volunteers were found to be safe and well tolerated in a phase I-ascending, single-dose study. Compound 1 estimated free observed maximum concentration in plasma (C max ) for 500-, 1,000-, and 2,000-mg doses were higher than the protein binding-corrected EC 50 required to inhibit 80% of the HRV serotypes tested. Treatment of HRV 52-infected cells with one to five 2-h pulses of 150 nM Compound 1 (corresponding to the C max at the 500-mg dose) was sufficient to effect a significant reduction in viral replication. These experiments highlight Compound 1 as a potent, orally bioavailable, irreversible inhibitor of HRV 3C protease and provide data that suggest that C max rather than the C min might be the key variable predicting clinical efficacy.The Picornaviridae comprise one of the largest families of known human and animal pathogens. Included in the picornavirus family are the human rhinoviruses (HRV) and human enteroviruses (HEV). Consisting of over 100 different serotypes, the HRV are the single most important etiological agents of the common cold (7,23,26). In most individuals, HRV infections are mild and self-limiting; however, in patients with underlying respiratory disorders, infections may result in exacerbations of asthma, cystic fibrosis, bronchitis, and chronic obstructive pulmonary disease (1,2,6,12,18,25,28). To date, there are no marketed antiviral therapies available for the prevention or treatment of HRV-related illnesses.We have focused our drug discovery efforts on the HRV 3C protease, an enzyme that is absolutely required for the majority of the proteolytic cleavage events that occur during the viral life cycle (7,17,19,23,26). DNA sequence comparisons among numerous HRV serotypes and several related picornaviruses have demonstrated a significant degree of homology among amino acid residues involved in key 3C protease inhibitor-binding interactions, providing an additional rationale for targeting research activities (3,20,22). Early drug discovery efforts led to the identification of ...

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Structure-Based Design, Synthesis, and Biological Evaluation of Irreversible Human Rhinovirus 3C Protease Inhibitors. 1. Michael Acceptor Structure−Activity Studies

Cited by 99 publications

References 58 publications

Selective inhibitors of picornavirus replication

Selective inhibitors of picornavirus replication

The Enterovirus 3C Protease Inhibitor SG85 Efficiently Blocks Rhinovirus Replication and Is Not Cross-Resistant with Rupintrivir

In Vitro Antiviral Activity and Single-Dose Pharmacokinetics in Humans of a Novel, Orally Bioavailable Inhibitor of Human Rhinovirus 3C Protease

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