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Sakander N, Ahmed A, Bhardwaj M, Kumari D, Nandi U, Mukherjee D. A path from synthesis to emergency use authorization of molnupiravir as a COVID-19 therapy. Bioorg Chem 2024; 147:107379. [PMID: 38643567 DOI: 10.1016/j.bioorg.2024.107379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 04/04/2024] [Accepted: 04/14/2024] [Indexed: 04/23/2024]
Abstract
Coronaviruses are a group of enveloped viruses with non-segmented, single-stranded, and positive-sense RNA genomes. It belongs to the 'Coronaviridae family', responsible for various diseases, including the common cold, SARS, and MERS. The COVID-19 pandemic, which began in March 2020, has affected 209 countries, infected over a million people, and claimed over 50,000 lives. Significant efforts have been made by repurposing several approved drugs including antiviral, to combat the COVID-19 pandemic. Molnupiravir is found to be the first orally acting efficacious drug to treat COVID-19 cases. It was approved for medical use in the UK in November 2021 and other countries, including USFDA, which granted approval an emergency use authorization (EUA) for treating adults with mild to moderate COVID-19 patients. Considering the importance of molnupiravir, the present review deals with its various synthetic strategies, pharmacokinetics, bio-efficacy, toxicity, and safety profiles. The comprehensive information along with critical analysis will be very handy for a wide range of audience including medicinal chemists in the arena of antiviral drug discovery especially anti-viral drugs against any variant of COVID-19.
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Affiliation(s)
- Norein Sakander
- Natural Product and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ajaz Ahmed
- Natural Product and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Mahir Bhardwaj
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India
| | - Diksha Kumari
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Infectious Diseases Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India
| | - Utpal Nandi
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India
| | - Debaraj Mukherjee
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Department of Chemical Sciences, Bose Institute, EN 80, Sector V, Bidhan Nagar, Kolkata 700091, WB, India.
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2
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Urbanowicz K, Opielka M, Stegmann KM, Dickmanns A, Dobbelstein M, Peters GJ, Smoleński RT. Evaluation of N4-hydroxycytidine incorporation into nucleic acids of SARS-CoV-2-infected host cells by direct measurement with liquid chromatography-mass spectrometry. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2024:1-9. [PMID: 38741480 DOI: 10.1080/15257770.2024.2346550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 04/16/2024] [Indexed: 05/16/2024]
Abstract
Molnupiravir, an orally administered prodrug of β-d-N4-hydroxycytidine (NHC), is incorporated into newly synthesized RNA by viral RNA-dependent RNA polymerase (RdRp). It is used for treatment of SARS-CoV-2 infections. Incorporation of NHC triphosphate into viral RNA inhibits replication of the virus, at least in part by introducing deleterious mutations. However, there is limited information on NHC incorporation into host RNA and reports on the risk of mutagenicity that molnupiravir/NHC pose to the host are conflicting. We used two liquid chromatography-mass spectrometry (LC-MS) methods to evaluate the incorporation of NHC into RNA and DNA of host Vero E6 cells in a SARS-CoV-2 infection model. To test this, host and viral RNA were degraded to their ribonucleosides, while host DNA was degraded to deoxyribonucleosides. Subsequently, nucleic acid constituents were analyzed by LC-MS, which offers specific, direct, and quantitative determination of incorporation. Our findings revealed concentration dependent NHC incorporation into host cell RNA in both infected and uninfected cell cultures, reaching a maximum of 1 in 7,093 bases. Analysis of host DNA revealed no presence of deoxy-N4-hydroxycytidine down to a detection limit of 1 in 133,000 bases. Our findings therefore suggest minimal to no NHC incorporation into host DNA, indicating a low probability of significant host cell mutagenicity associated with its use.
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Affiliation(s)
| | - Mikolaj Opielka
- Department of Biochemistry, Medical University of Gdansk, Gdansk, Poland
| | - Kim M Stegmann
- Department of Molecular Oncology, Göttingen Center of Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Antje Dickmanns
- Department of Molecular Oncology, Göttingen Center of Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Matthias Dobbelstein
- Department of Molecular Oncology, Göttingen Center of Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Godefridus J Peters
- Department of Biochemistry, Medical University of Gdansk, Gdansk, Poland
- Laboratory of Medical Oncology, Amsterdam University Medical Centers, Cancer Center Amsterdam, Vrije Unversteit Amsterdam, Amsterdam, the Netherlands
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3
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Chen K, Jackson NJ, Kelesidis T. Mitoquinone mesylate as post-exposure prophylaxis against SARS-CoV-2 infection in humans: an exploratory single center pragmatic open label non-randomized pilot clinical trial with matched controls. EBioMedicine 2024; 102:105042. [PMID: 38471990 PMCID: PMC11026948 DOI: 10.1016/j.ebiom.2024.105042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND An ongoing important need exists to rapidly develop novel therapeutics for COVID-19 that will retain antiviral efficacy in the setting of rapidly evolving SARS-CoV-2 variants and potential future development of resistance of SARS-COV-2 to remdesivir and protease inhibitors. To date, there is no FDA-approved treatment for post-exposure prophylaxis against SAR-CoV-2. We have shown that the mitochondrial antioxidant mitoquinone/mitoquinol mesylate (Mito-MES), a dietary supplement, has antiviral activity against SARS-CoV-2 in vitro and in SARS-CoV-2 infected K18-hACE2 mice. METHODS In this exploratory, pragmatic open label clinical trial (ClinicalTrials.gov identifier NCT05381454), we studied whether Mito-MES is an effective post-exposure prophylaxis treatment in people who had high-grade unmasked exposures to SARS-CoV-2 within 5 days prior to study entry. Participants were enrolled in real-world setting in Los Angeles, United States between May 1 and December 1, 2022 and were assigned to either mito-MES 20 mg daily for 14 days (n = 40) or no mito-MES (controls) (n = 40). The primary endpoint was development of SARS-CoV-2 infection based on 4 COVID-19 diagnostic tests [rapid antigen tests (RATs) or PCR] performed during the study period (14 days post exposure). FINDINGS Out of 40 (23 females; 57.5%) study participants who took Mito-MES, 12 (30%) developed SARS-CoV-2 infection compared to 30 of the 40 controls (75%) (difference -45.0%, 95% confidence intervals (CI): -64.5%, -25.5%). Out of 40 (19 females; 47.5%) study participants in the control group, 30 (75.0%) had at least one positive COVID-19 diagnostic test and 23 (57.5%) were symptomatic. With regards to key secondary outcomes, among symptomatic SARS-CoV-2 infections, the median duration of viral symptoms was lower in the Mito-MES group (median 3.0, 95% CI 2.75, 3.25) compared to the control group (median 5.0, 95% CI 4.0, 7.0). None of the study participants was hospitalized or required oxygen therapy. Mito-MES was well tolerated and no serious side effect was reported in any study participant. INTERPRETATION This work describes antiviral activity of mito-MES in humans. Mito-MES was well tolerated in our study population and attenuated transmission of SARS-CoV-2 infection. Given established safety of Mito-MES in humans, our results suggest that randomized control clinical trials of Mito-MES as post-exposure prophylaxis against SARS-CoV-2 infection are warranted. FUNDING This work was supported in part by National Institutes of Health grant R01AG059501 (TK), National Institutes of Health grant R01AG059502 04S1 (TK), NIH/National Center for Advancing Translational Sciences (NCATS) UCLA CTSI Grant Number UL1TR001881 and California HIV/AIDS Research Program grant OS17-LA-002 (TK).
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Affiliation(s)
- Keren Chen
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Nicholas J Jackson
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Theodoros Kelesidis
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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4
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Kiy RT, Khoo SH, Chadwick AE. Assessing the mitochondrial safety profile of the molnupiravir active metabolite, β-d-N4-hydroxycytidine (NHC), in the physiologically relevant HepaRG model. Toxicol Res (Camb) 2024; 13:tfae012. [PMID: 38328743 PMCID: PMC10848230 DOI: 10.1093/toxres/tfae012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 02/09/2024] Open
Abstract
Background β-d-N4-Hydroxycytidine (NHC) is the active metabolite of molnupiravir, a broad-spectrum antiviral approved by the MHRA for COVID-19 treatment. NHC induces lethal mutagenesis of the SARS-CoV-2 virus, undergoing incorporation into the viral genome and arresting viral replication. It has previously been reported that several nucleoside analogues elicit off-target inhibition of mitochondrial DNA (mtDNA) or RNA replication. Although NHC does not exert these effects in HepG2 cells, HepaRG are proven to be advantageous over HepG2 for modelling nucleoside analogue-induced mitochondrial dysfunction. Therefore, the objective of this work was to assess the mitotoxic potential of NHC in HepaRG cells, a model more closely resembling physiological human liver. Methods Differentiated HepaRG cells were exposed to 1-60 μM NHC for 3-14 days to investigate effects of sub-, supra-, and clinically-relevant exposures (in the UK, molnupiravir for COVID-19 is indicated for 5 days and reported Cmax is 16 μM). Following drug incubation, cell viability, mtDNA copy number, mitochondrial protein expression, and mitochondrial respiration were assessed. Results NHC induced minor decreases in cell viability at clinically relevant exposures, but did not decrease mitochondrial protein expression. The effects on mtDNA were variable, but typically copy number was increased. At supra-clinical concentrations (60 μM), NHC reduced mitochondrial respiration, but did not appear to induce direct electron transport chain dysfunction. Conclusions Overall, NHC does not cause direct mitochondrial toxicity in HepaRG cells at clinically relevant concentrations, but may induce minor cellular perturbations. As HepaRG cells have increased physiological relevance, these findings provide additional assurance of the mitochondrial safety profile of NHC.
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Affiliation(s)
- Robyn T Kiy
- Department of Pharmacology and Therapeutics, University of Liverpool, Sherrington Building, Ashton Street, Liverpool, L69 3GE, United Kingdom
| | - Saye H Khoo
- Department of Pharmacology and Therapeutics, University of Liverpool, Sherrington Building, Ashton Street, Liverpool, L69 3GE, United Kingdom
- Tropical Infectious Diseases Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, United Kingdom
| | - Amy E Chadwick
- Department of Pharmacology and Therapeutics, University of Liverpool, Sherrington Building, Ashton Street, Liverpool, L69 3GE, United Kingdom
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Persaud KE, Sahu RR, Neary MC, Kapdi AR, Lakshman MK. Two short approaches to the COVID-19 drug β-D- N4-hydroxycytidine and its prodrug molnupiravir. Org Biomol Chem 2024; 22:735-740. [PMID: 38168802 DOI: 10.1039/d3ob02039h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Molnupiravir, the prodrug for β-D-N4-hydroxycytidine (NHC), is marketed by Merck as Lagevrio™ against mild-moderate COVID-19, under FDA emergency use authorization. It is the first oral drug against the disease. This work describes two synthetic approaches to NHC and molnupiravir by amide activation in uridine with a peptide-coupling agent and with a 4-chloropyrimidinone nucleoside intermediate.
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Affiliation(s)
- Kevin E Persaud
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Rajesh R Sahu
- Department of Chemistry, Institute of Chemical Technology, Nathalal Parekh Road, Matunga, Mumbai 400019, India
| | - Michelle C Neary
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, NY 10065, USA
| | - Anant R Kapdi
- Department of Chemistry, Institute of Chemical Technology, Nathalal Parekh Road, Matunga, Mumbai 400019, India
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
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Marikawa Y, Alarcon VB. An active metabolite of the anti-COVID-19 drug molnupiravir impairs mouse preimplantation embryos at clinically relevant concentrations. Reprod Toxicol 2023; 121:108475. [PMID: 37748715 PMCID: PMC10671791 DOI: 10.1016/j.reprotox.2023.108475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 09/04/2023] [Accepted: 09/21/2023] [Indexed: 09/27/2023]
Abstract
Molnupiravir is a nucleoside analog antiviral that is authorized for use in the treatment of COVID-19. For its therapeutic action, molnupiravir is converted after ingestion to the active metabolite N4-hydroxycytidine, which is incorporated into the viral genome to cause lethal mutagenesis. Molnupiravir is not recommended for use during pregnancy, because preclinical animal studies suggest that it is hazardous to developing embryos. However, the mechanisms underlying the embryotoxicity of molnupiravir are currently unknown. To gain mechanistic insights into its embryotoxic action, the effects of molnupiravir and N4-hydroxycytidine were examined on the in vitro development of mouse preimplantation embryos. Molnupiravir did not prevent blastocyst formation even at concentrations that were much higher than the therapeutic plasma levels. By contrast, N4-hyroxycytidine exhibited potent toxicity, as it interfered with blastocyst formation and caused extensive cell death at concentrations below the therapeutic plasma levels. The adverse effects of N4-hydroxycytidine were dependent on the timing of exposure, such that treatment after the 8-cell stage, but not before it, caused embryotoxicity. Transcriptomic analysis of N4-hydroxycytidine-exposed embryos, together with the examination of eIF-2a protein phosphorylation level, suggested that N4-hydroxycytidine induced the integrated stress response. The adverse effects of N4-hydroxycytidine were significantly alleviated by the co-treatment with S-(4-nitrobenzyl)-6-thioinosine, suggesting that the embryotoxic potential of N4-hydroxycytidine requires the activity of nucleoside transporters. These findings show that the active metabolite of molnupiravir impairs preimplantation development at clinically relevant concentrations, providing mechanistic foundation for further studies on the embryotoxic potential of molnupiravir and other related nucleoside antivirals.
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Affiliation(s)
- Yusuke Marikawa
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, University of Hawaii John A. Burns School of Medicine, Honolulu, HI 96813, USA
| | - Vernadeth B Alarcon
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, University of Hawaii John A. Burns School of Medicine, Honolulu, HI 96813, USA.
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Shannon A, Canard B. Kill or corrupt: Mechanisms of action and drug-resistance of nucleotide analogues against SARS-CoV-2. Antiviral Res 2023; 210:105501. [PMID: 36567022 PMCID: PMC9773703 DOI: 10.1016/j.antiviral.2022.105501] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
Nucleoside/tide analogues (NAs) have long been used in the fight against viral diseases, and now present a promising option for the treatment of COVID-19. Once activated to the 5'-triphosphate state, NAs act by targeting the viral RNA-dependent RNA-polymerase for incorporation into the viral RNA genome. Incorporated analogues can either 'kill' (terminate) synthesis, or 'corrupt' (genetically or chemically) the RNA. Against coronaviruses, the use of NAs has been further complicated by the presence of a virally encoded exonuclease domain (nsp14) with proofreading and repair capacities. Here, we describe the mechanism of action of four promising anti-COVID-19 NAs; remdesivir, molnupiravir, favipiravir and bemnifosbuvir. Their distinct mechanisms of action best exemplify the concept of 'killers' and 'corruptors'. We review available data regarding their ability to be incorporated and excised, and discuss the specific structural features that dictate their overall potency, toxicity, and mutagenic potential. This should guide the synthesis of novel analogues, lend insight into the potential for resistance mutations, and provide a rational basis for upcoming combinations therapies.
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Affiliation(s)
- Ashleigh Shannon
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille, Cedex 09, France
| | - Bruno Canard
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille, Cedex 09, France.
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Chary MA, Barbuto AF, Izadmehr S, Tarsillo M, Fleischer E, Burns MM. COVID-19 Therapeutics: Use, Mechanism of Action, and Toxicity (Xenobiotics). J Med Toxicol 2023; 19:26-36. [PMID: 36525217 PMCID: PMC9756926 DOI: 10.1007/s13181-022-00918-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/23/2022] Open
Abstract
SARS-CoV-2 emerged in 2019 and led to the COVID-19 pandemic. Efforts to develop therapeutics against SARS-Cov-2 led to both new treatments and attempts to repurpose existing medications. Here, we provide a narrative review of the xenobiotics and alternative remedies used or proposed to treat COVID-19. Most repositioned xenobiotics have had neither the feared toxicity nor the anticipated efficacy. Repurposed viral replication inhibitors are not efficacious and frequently associated with nausea, vomiting, and diarrhea. Antiviral medications designed specifically against SARS-CoV-2 may prevent progression to severe disease in at-risk individuals and appear to have a wide therapeutic index. Colloidal silver, zinc, and ivermectin have no demonstrated efficacy. Ivermectin has a wide therapeutic index but is not efficacious and acquiring it from veterinary sources poses additional danger. Chloroquine has a narrow therapeutic index and no efficacy. A companion review covers vaccines, monoclonal antibodies, and immunotherapies. Together, these two reviews form an update to our 2020 review.
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Affiliation(s)
- Michael A Chary
- Division of Medical Toxicology, Department of Emergency Medicine, Boston Children's Hospital, Boston, MA, USA.
- Regional Center for Poison Control and Prevention Serving Massachusetts and Rhode Island, Boston, MA, USA.
- Division of Medical Toxicology, Department of Emergency Medicine, Weill Cornell Medical College, New York, NY, USA.
| | - Alexander F Barbuto
- Division of Medical Toxicology, Department of Emergency Medicine, Boston Children's Hospital, Boston, MA, USA
- Regional Center for Poison Control and Prevention Serving Massachusetts and Rhode Island, Boston, MA, USA
- Department of Emergency Medicine, Carl R. Darnall Army Medical Center, Fort Hood, TX, USA
| | - Sudeh Izadmehr
- Division of Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marc Tarsillo
- Division of Medical Toxicology, Department of Emergency Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Eduardo Fleischer
- Division of Medical Toxicology, Department of Emergency Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Michele M Burns
- Division of Medical Toxicology, Department of Emergency Medicine, Boston Children's Hospital, Boston, MA, USA
- Regional Center for Poison Control and Prevention Serving Massachusetts and Rhode Island, Boston, MA, USA
- Department of Emergency Medicine, Brigham and Women's Hospital, Boston, MA, USA
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Stevaert A, Groaz E, Naesens L. Nucleoside analogs for management of respiratory virus infections: mechanism of action and clinical efficacy. Curr Opin Virol 2022; 57:101279. [PMID: 36403338 PMCID: PMC9671222 DOI: 10.1016/j.coviro.2022.101279] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/14/2022] [Accepted: 10/20/2022] [Indexed: 11/18/2022]
Abstract
The COVID-19 pandemic has accelerated the development of nucleoside analogs to treat respiratory virus infections, with remdesivir being the first compound to receive worldwide authorization and three other nucleoside analogs (i.e. favipiravir, molnupiravir, and bemnifosbuvir) in the pipeline. Here, we summarize the current knowledge concerning their clinical efficacy in suppressing the virus and reducing the need for hospitalization or respiratory support. We also mention trials of favipiravir and lumicitabine, for influenza and respiratory syncytial virus, respectively. Besides, we outline how nucleoside analogs interact with the polymerases of respiratory viruses, to cause lethal virus mutagenesis or disturbance of viral RNA synthesis. In this way, we aim to convey the key findings on this rapidly evolving class of respiratory virus medication.
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Affiliation(s)
- Annelies Stevaert
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, Herestraat 49 box 1043, B-3000 Leuven, Belgium
| | - Elisabetta Groaz
- Rega Institute for Medical Research, Medicinal Chemistry, KU Leuven, Herestraat 49 box 1041, B-3000 Leuven, Belgium; Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
| | - Lieve Naesens
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, Herestraat 49 box 1043, B-3000 Leuven, Belgium.
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Cook S, Wittenburg L, Yan VC, Theil JH, Castillo D, Reagan KL, Williams S, Pham CD, Li C, Muller FL, Murphy BG. An Optimized Bioassay for Screening Combined Anticoronaviral Compounds for Efficacy against Feline Infectious Peritonitis Virus with Pharmacokinetic Analyses of GS-441524, Remdesivir, and Molnupiravir in Cats. Viruses 2022; 14:v14112429. [PMID: 36366527 PMCID: PMC9697187 DOI: 10.3390/v14112429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/28/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
Feline infectious peritonitis (FIP) is a fatal disease of cats that currently lacks licensed and affordable vaccines or antiviral therapeutics. The disease has a spectrum of clinical presentations including an effusive ("wet") form and non-effusive ("dry") form, both of which may be complicated by neurologic or ocular involvement. The feline coronavirus (FCoV) biotype, termed feline infectious peritonitis virus (FIPV), is the etiologic agent of FIP. The objective of this study was to determine and compare the in vitro antiviral efficacies of the viral protease inhibitors GC376 and nirmatrelvir and the nucleoside analogs remdesivir (RDV), GS-441524, molnupiravir (MPV; EIDD-2801), and β-D-N4-hydroxycytidine (NHC; EIDD-1931). These antiviral agents were functionally evaluated using an optimized in vitro bioassay system. Antivirals were assessed as monotherapies against FIPV serotypes I and II and as combined anticoronaviral therapies (CACT) against FIPV serotype II, which provided evidence for synergy for selected combinations. We also determined the pharmacokinetic properties of MPV, GS-441524, and RDV after oral administration to cats in vivo as well as after intravenous administration of RDV. We established that orally administered MPV at 10 mg/kg, GS-441524 and RDV at 25 mg/kg, and intravenously administered RDV at 7 mg/kg achieves plasma levels greater than the established corresponding EC50 values, which are sustained over 24 h for GS-441514 and RDV.
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Affiliation(s)
- Sarah Cook
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
- Correspondence:
| | - Luke Wittenburg
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Victoria C. Yan
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Jacob H. Theil
- Office of Research, Campus Veterinary Services, University of California-Davis, Davis, CA 95616, USA
| | - Diego Castillo
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Krystle L. Reagan
- Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Sonyia Williams
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Cong-Dat Pham
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Chun Li
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Florian L. Muller
- Sporos Bioventures, @JLABS Suite 201, 2450 Holcombe Blvd, Houston, TX 77021, USA
| | - Brian G. Murphy
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
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Wang LG, Wang L. Current Strategies in Treating Cytokine Release Syndrome Triggered by Coronavirus SARS-CoV-2. Immunotargets Ther 2022; 11:23-35. [PMID: 35611161 PMCID: PMC9124488 DOI: 10.2147/itt.s360151] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 05/07/2022] [Indexed: 12/15/2022] Open
Abstract
Since the beginning of the SARS-CoV-2 pandemic, the treatments and management of the deadly COVID-19 disease have made great progress. The strategies for developing novel treatments against COVID-19 include antiviral small molecule drugs, cell and gene therapies, immunomodulators, neutralizing antibodies, and combination therapies. Among them, immunomodulators are the most studied treatments. The small molecule antiviral drugs and immunoregulators are expected to be effective against viral variants of SARS-CoV-2 as these drugs target either conservative parts of the virus or common pathways of inflammation. Although the immunoregulators have shown benefits in reducing mortality of cytokine release syndrome (CRS) triggered by SARS-CoV-2 infections, extensive investigations on this class of treatment to launch novel therapies that substantially improve efficacy and reduce side effects are still warranted. Moreover, great challenges have emerged as the SARS-CoV-2 virus quickly, frequently, and continuously evolved. This review provides an update and summarizes the recent advances in the treatment of COVID-19 and in particular emphasized the strategies in managing CRS triggered by SARS-CoV-2. A brief perspective in the battle against the deadly disease was also provided.
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Affiliation(s)
- Long G Wang
- Department of Research and Development, Natrogen Therapeutics International, Inc., Valhalla, NY, USA
- Correspondence: Long G Wang, Department of Research and Development, Natrogen Therapeutics International, Inc., Vosburgh 213, NYMC Campus, Valhalla, NY, 10595, USA, Tel +1 646 229-7583, Email
| | - Luxi Wang
- Department of Clinical Research, Clinipace Clinical Research, Morrisville, NC, USA
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12
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Wallace K, Bjork J. Molnupiravir; molecular and functional descriptors of mitochondrial safety. Toxicol Appl Pharmacol 2022; 442:116003. [PMID: 35358570 PMCID: PMC8958731 DOI: 10.1016/j.taap.2022.116003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/21/2022] [Accepted: 03/24/2022] [Indexed: 12/16/2022]
Abstract
Molnupiravir is an orally active nucleoside analog antiviral drug that recently was approved by the U.S. FDA for emergency treatment of adult patients infected with the SARS-CoV-2 (COVID-19) virus and at risk for severe progression. The active form of the drug, N-hydroxycytidine (NHC) triphosphate competes for incorporation by RNA-dependent RNA-polymerase (RdRp) into the replicating viral genome resulting in mutations and arrest of the replicating virus. Historically, some nucleoside analog antiviral drugs have been found to lack specificity for the virus and also inhibit replication and/or expression of the mitochondrial genome. The objective of the present study was to test whether molnupiravir and/or NHC also target mitochondrial DNA polymerase gamma (PolG) or RNA polymerase (POLRMT) activity to inhibit the replication and/or expression of the mitochondrial genome leading to impaired mitochondrial function. Human-derived HepG2 cells were exposed for 48 h in culture to increasing concentrations of either molnupiravir or NHC after which cytotoxicity, mtDNA copy number and mitochondrial gene expression were determined. The phenotypic endpoint, mitochondrial respiration, was measured with the Seahorse® XF96 Extracellular Flux Analyzer. Both molnupiravir and NHC were cytotoxic at concentrations of ≥10 μM. However, at non-cytotoxic concentrations, neither significantly altered mitochondrial gene dose or transcription, or mitochondrial respiration. From this we conclude that mitochondrial toxicity is not a primary off target in the mechanism of cytotoxicity for either molnupiravir or its active metabolite NHC in the HepG2 cell line.
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13
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Hashemian SMR, Pourhanifeh MH, Hamblin MR, Shahrzad MK, Mirzaei H. RdRp inhibitors and COVID-19: Is molnupiravir a good option? Biomed Pharmacother 2022; 146:112517. [PMID: 34902743 PMCID: PMC8654603 DOI: 10.1016/j.biopha.2021.112517] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 12/15/2022] Open
Abstract
Rapid changes in the viral genome allow viruses to evade threats posed by the host immune response or antiviral drugs, and can lead to viral persistence in the host cells. RNA-dependent RNA polymerase (RdRp) is an essential enzyme in RNA viruses, which is involved in RNA synthesis through the formation of phosphodiester bonds. Therefore, in RNA viral infections such as SARS-CoV-2, RdRp could be a crucial therapeutic target. The present review discusses the promising application of RdRp inhibitors, previously approved or currently being tested in human clinical trials, in the treatment of RNA virus infections. Nucleoside inhibitors (NIs) bind to the active site of RdRp, while nonnucleoside inhibitors (NNIs) bind to allosteric sites. Given the absence of highly effective drugs for the treatment of COVID-19, the discovery of an efficient treatment for this pandemic is an urgent concern for researchers around the world. We review the evidence for molnupiravir (MK-4482, EIDD-2801), an antiviral drug originally designed for Alphavirus infections, as a potential preventive and therapeutic agent for the management of COVID-19. At the beginning of this pandemic, molnupiravir was in preclinical development for seasonal influenza. When COVID-19 spread dramatically, the timeline for development was accelerated to focus on the treatment of this pandemic. Real time consultation with regulators took place to expedite this program. We summarize the therapeutic potential of RdRp inhibitors, and highlight molnupiravir as a new small molecule drug for COVID-19 treatment.
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Affiliation(s)
- Seyed Mohammad Reza Hashemian
- Chronic Respiratory Diseases Research Center (CRDRC), National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Michael R. Hamblin
- Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein 2028, South Africa
| | - Mohammad Karim Shahrzad
- Department of Internal Medicine and Endocrinology, ShohadaeTajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Hamed Mirzaei
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran; Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, IR, Iran.
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14
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Singla S, Goyal S. Antiviral activity of molnupiravir against COVID-19: a schematic review of evidences. BULLETIN OF THE NATIONAL RESEARCH CENTRE 2022; 46:62. [PMID: 35287311 PMCID: PMC8907909 DOI: 10.1186/s42269-022-00753-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 03/02/2022] [Indexed: 05/07/2023]
Abstract
BACKGROUND The study was aimed at encapsulating the evidence of in vitro and in vivo antiviral activities of molnupiravir and its active form against highly pathogenic SARS-CoV-2, the pathogen responsible for COVID-19, and finding out the efficacy and safety of molnupiravir in clinical trials. MAIN BODY Information on publications was explored on several databases, gray literature was reviewed, and the outcomes were discussed narratively. Molnupiravir's antiviral efficacy and associated mechanism of action have been verified in vitro against both non-COVID and multiple coronaviruses. Molnupiravir has been tried in preclinical investigations in numerous animal models against non-coronaviruses. Clinical studies in several countries are now being conducted to evaluate its antiviral efficacy in persons infected with COVID-19. The medication displays antiviral effect via generation of copying mistakes during viral RNA replication. CONCLUSIONS Molnupiravir is the first oral antiviral medicine to show considerable and convincing antiviral activity in vitro and in animal models. Molnupiravir stops the spread of SARS-CoV-2 in animals that have been infected and in cells grown in a lab. In a clinical research, early molnupiravir treatment reduced hospitalization and death risk in unvaccinated individuals with COVID-19. In the battle against SARS-CoV-2, it could be a potent weapon. However, its role in COVID-19 in moderate to severe cases is still up in the air, and more research is needed.
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Affiliation(s)
- Shivali Singla
- Department of Pharmaceutics, School of Pharmacy, Abhilashi University, Chail Chowk, HP 175028 India
| | - Sachin Goyal
- Department of Pharmaceutics, School of Pharmacy, Abhilashi University, Chail Chowk, HP 175028 India
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15
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Waters MD, Warren S, Hughes C, Lewis P, Zhang F. Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: The special case of molnupiravir. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2022; 63:37-63. [PMID: 35023215 DOI: 10.1002/em.22471] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/28/2021] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
This review considers antiviral nucleoside analog drugs, including ribavirin, favipiravir, and molnupiravir, which induce genome error catastrophe in SARS-CoV or SARS-CoV-2 via lethal mutagenesis as a mode of action. In vitro data indicate that molnupiravir may be 100 times more potent as an antiviral agent than ribavirin or favipiravir. Molnupiravir has recently demonstrated efficacy in a phase 3 clinical trial. Because of its anticipated global use, its relative potency, and the reported in vitro "host" cell mutagenicity of its active principle, β-d-N4-hydroxycytidine, we have reviewed the development of molnupiravir and its genotoxicity safety evaluation, as well as the genotoxicity profiles of three congeners, that is, ribavirin, favipiravir, and 5-(2-chloroethyl)-2'-deoxyuridine. We consider the potential genetic risks of molnupiravir on the basis of all available information and focus on the need for additional human genotoxicity data and follow-up in patients treated with molnupiravir and similar drugs. Such human data are especially relevant for antiviral NAs that have the potential of permanently modifying the genomes of treated patients and/or causing human teratogenicity or embryotoxicity. We conclude that the results of preclinical genotoxicity studies and phase 1 human clinical safety, tolerability, and pharmacokinetics are critical components of drug safety assessments and sentinels of unanticipated adverse health effects. We provide our rationale for performing more thorough genotoxicity testing prior to and within phase 1 clinical trials, including human PIG-A and error corrected next generation sequencing (duplex sequencing) studies in DNA and mitochondrial DNA of patients treated with antiviral NAs that induce genome error catastrophe via lethal mutagenesis.
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Affiliation(s)
- Michael D Waters
- Michael Waters Consulting USA, Hillsborough, North Carolina, USA
| | | | - Claude Hughes
- Duke University Medical Center, Durham, North Carolina, USA
| | | | - Fengyu Zhang
- Global Clinical and Translational Research Institute, Bethesda, Maryland, USA
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16
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Focosi D, Maggi F, McConnell S, Casadevall A. Very low levels of remdesivir resistance in SARS-COV-2 genomes after 18 months of massive usage during the COVID19 pandemic: A GISAID exploratory analysis. Antiviral Res 2022; 198:105247. [PMID: 35033572 PMCID: PMC8755559 DOI: 10.1016/j.antiviral.2022.105247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/06/2022] [Accepted: 01/10/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Daniele Focosi
- North-Western Tuscany Blood Bank, Pisa University Hospital, Pisa, Italy.
| | - Fabrizio Maggi
- Department of Medicine and Surgery, University of Insubria, Varese, Italy; Laboratory of Microbiology, ASST Sette Laghi, Varese, Italy.
| | - Scott McConnell
- Department of Medicine, Johns Hopkins School of Public Health and School of Medicine, Baltimore, MD, USA.
| | - Arturo Casadevall
- Department of Medicine, Johns Hopkins School of Public Health and School of Medicine, Baltimore, MD, USA.
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17
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Wu J, Chen Z, Han X, Chen Q, Wang Y, Feng T. SARS-CoV-2 RNA-dependent RNA polymerase as a target for high-throughput drug screening. Future Virol 2022:10.2217/fvl-2021-0335. [PMID: 36794167 PMCID: PMC9910510 DOI: 10.2217/fvl-2021-0335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/06/2023] [Indexed: 02/05/2023]
Abstract
The ongoing COVID-19 pandemic caused by the SARS-CoV-2 has necessitated rapid development of drug screening tools. RNA-dependent RNA polymerase (RdRp) is a promising target due to its essential functions in replication and transcription of viral genome. To date, through minimal RNA synthesizing machinery established from cryo-electron microscopy structural data, there has been development of high-throughput screening assays for directly screening inhibitors that target the SARS-CoV-2 RdRp. Here, we analyze and present verified techniques that could be used to discover potential anti-RdRp agents or repurposing of approved drugs to target the SARS-CoV-2 RdRp. In addition, we highlight the characteristics and application value of cell-free or cell-based assays in drug discovery.
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Affiliation(s)
- Jiahui Wu
- 1Institute of Biology & Medical Sciences, Jiangsu Key Laboratory of Infection & Immunity, Soochow University, Suzhou, 215123, Jiangsu Province, China
| | - Zhiqiang Chen
- 1Institute of Biology & Medical Sciences, Jiangsu Key Laboratory of Infection & Immunity, Soochow University, Suzhou, 215123, Jiangsu Province, China,2Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, Jiangsu Province, China
| | - Xue Han
- 3Department of Clinical Laboratory, the Affiliated Hospital of Qingdao University, 59 Haier Road, Qingdao, 266000, Shandong Province, China
| | - Qiaoqiao Chen
- 1Institute of Biology & Medical Sciences, Jiangsu Key Laboratory of Infection & Immunity, Soochow University, Suzhou, 215123, Jiangsu Province, China
| | - Yintao Wang
- 1Institute of Biology & Medical Sciences, Jiangsu Key Laboratory of Infection & Immunity, Soochow University, Suzhou, 215123, Jiangsu Province, China
| | - Tingting Feng
- 1Institute of Biology & Medical Sciences, Jiangsu Key Laboratory of Infection & Immunity, Soochow University, Suzhou, 215123, Jiangsu Province, China,Author for correspondence: Tel.: +86 512 6588 2429;
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18
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Parsons TL, Kryszak LA, Marzinke MA. Development and validation of assays for the quantification of β-D-N 4-hydroxycytidine in human plasma and β-D-N 4-hydroxycytidine-triphosphate in peripheral blood mononuclear cell lysates. J Chromatogr B Analyt Technol Biomed Life Sci 2021; 1182:122921. [PMID: 34555541 PMCID: PMC8411588 DOI: 10.1016/j.jchromb.2021.122921] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 12/05/2022]
Abstract
The novel antiviral prodrug molnupiravir is under evaluation for the treatment of SARS-CoV-2. Molnupiravir is converted to β-D-N4-hydroxycytidine (NHC), which is the primary form found in systemic circulation. β-D-N4-hydroxycytidine-triphosphate (NHCtp) is the bioactive anabolite produced intracellularly. Sensitive and accurate bioanalytical methods are required to characterize NHC and NHCtp pharmacokinetics in clinical trials. Human K2EDTA plasma or peripheral blood mononuclear cell (PBMC) lysates were spiked with NHC (plasma) or NHCtp (PBMC), respectively. Following the addition of isotopically-labeled internal standards and sample extraction via protein precipitation or lysate dilution, respectively, samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. Methods were validated in accordance with FDA Bioanalytical Method Validation recommendations. NHC can be quantified in plasma with a lower limit of quantification (LLOQ) of 1 ng/mL; the primary linearity of the assay is 1–5000 ng/mL. Assay precision and accuracy were ≤ 6.40% and ≤ ± 6.37%, respectively. NHC is unstable in whole blood and has limited stability in plasma at room temperature. The calibration range for NHCtp in PBMC lysates is 1–1500 pmol/sample, and the assay has an LLOQ of 1 pmol/sample. Assay precision and accuracy were ≤ 11.8% and ≤± 11.2%. Ion suppression was observed for both analytes; isotopically-labeled internal standards showed comparable ion suppression, resulting in negligible (<5%) relative matrix effects. Sensitive, specific, and dynamic LC-MS/MS assays have been developed and validated for the quantification of NHC in plasma and NHCtp in PBMC lysates. The described methods are appropriate for use in clinical trials.
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Affiliation(s)
- Teresa L Parsons
- Department of Medicine, Johns Hopkins University, 5200 Eastern Ave, Mason F. Lord Tower, Suite 6000, Baltimore, MD 21224, USA
| | - Lindsay A Kryszak
- Department of Medicine, Johns Hopkins University, 5200 Eastern Ave, Mason F. Lord Tower, Suite 6000, Baltimore, MD 21224, USA
| | - Mark A Marzinke
- Department of Medicine, Johns Hopkins University, 5200 Eastern Ave, Mason F. Lord Tower, Suite 6000, Baltimore, MD 21224, USA; Department of Pathology, Johns Hopkins University, 1800 Orleans St., Sheikh Zayed Tower, Baltimore MD 21287, USA.
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19
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Affiliation(s)
- Brandon Malone
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, USA
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, USA.
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20
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Kabinger F, Stiller C, Schmitzová J, Dienemann C, Kokic G, Hillen HS, Höbartner C, Cramer P. Mechanism of molnupiravir-induced SARS-CoV-2 mutagenesis. Nat Struct Mol Biol 2021; 28:740-746. [PMID: 34381216 DOI: 10.1101/2021.05.11.443555] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 07/28/2021] [Indexed: 05/20/2023]
Abstract
Molnupiravir is an orally available antiviral drug candidate currently in phase III trials for the treatment of patients with COVID-19. Molnupiravir increases the frequency of viral RNA mutations and impairs SARS-CoV-2 replication in animal models and in humans. Here, we establish the molecular mechanisms underlying molnupiravir-induced RNA mutagenesis by the viral RNA-dependent RNA polymerase (RdRp). Biochemical assays show that the RdRp uses the active form of molnupiravir, β-D-N4-hydroxycytidine (NHC) triphosphate, as a substrate instead of cytidine triphosphate or uridine triphosphate. When the RdRp uses the resulting RNA as a template, NHC directs incorporation of either G or A, leading to mutated RNA products. Structural analysis of RdRp-RNA complexes that contain mutagenesis products shows that NHC can form stable base pairs with either G or A in the RdRp active center, explaining how the polymerase escapes proofreading and synthesizes mutated RNA. This two-step mutagenesis mechanism probably applies to various viral polymerases and can explain the broad-spectrum antiviral activity of molnupiravir.
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Affiliation(s)
- Florian Kabinger
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Carina Stiller
- Universität Würzburg, Lehrstuhl für Organische Chemie I, Würzburg, Germany
| | - Jana Schmitzová
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Christian Dienemann
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Goran Kokic
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Hauke S Hillen
- University Medical Center Göttingen, Department of Cellular Biochemistry, Göttingen, Germany
- Max Planck Institute for Biophysical Chemistry, Research Group Structure and Function of Molecular Machines, Göttingen, Germany
| | - Claudia Höbartner
- Universität Würzburg, Lehrstuhl für Organische Chemie I, Würzburg, Germany.
| | - Patrick Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany.
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21
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Abstract
The recent outbreak of COVID-19 has affected human lives severely. The human-to-human transmission of this viral disease has become deadly due to the unavailability of COVID-19 specific drugs. Here, an overview of various attempts made to design different therapeutic agents against various structural and non-structural proteins of SARS-CoV-2 has been summarized. Emphasis has been made to highlight the mechanisms of drug action and ways to design better inhibitors of these proteins. The roles of anti-oxidants and vitamins in suppressing COVID-19 are also discussed.
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22
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Gordon CJ, Tchesnokov EP, Schinazi RF, Götte M. Molnupiravir promotes SARS-CoV-2 mutagenesis via the RNA template. J Biol Chem 2021; 297:100770. [PMID: 33989635 PMCID: PMC8110631 DOI: 10.1016/j.jbc.2021.100770] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 04/29/2021] [Accepted: 05/09/2021] [Indexed: 01/01/2023] Open
Abstract
The RNA-dependent RNA polymerase of the severe acute respiratory syndrome coronavirus 2 is an important target in current drug development efforts for the treatment of coronavirus disease 2019. Molnupiravir is a broad-spectrum antiviral that is an orally bioavailable prodrug of the nucleoside analogue β-D-N4-hydroxycytidine (NHC). Molnupiravir or NHC can increase G to A and C to U transition mutations in replicating coronaviruses. These increases in mutation frequencies can be linked to increases in antiviral effects; however, biochemical data of molnupiravir-induced mutagenesis have not been reported. Here we studied the effects of the active compound NHC 5’-triphosphate (NHC-TP) against the purified severe acute respiratory syndrome coronavirus 2 RNA-dependent RNA polymerase complex. The efficiency of incorporation of natural nucleotides over the efficiency of incorporation of NHC-TP into model RNA substrates followed the order GTP (12,841) > ATP (424) > UTP (171) > CTP (30), indicating that NHC-TP competes predominantly with CTP for incorporation. No significant inhibition of RNA synthesis was noted as a result of the incorporated monophosphate in the RNA primer strand. When embedded in the template strand, NHC-monophosphate supported the formation of both NHC:G and NHC:A base pairs with similar efficiencies. The extension of the NHC:G product was modestly inhibited, but higher nucleotide concentrations could overcome this blockage. In contrast, the NHC:A base pair led to the observed G to A (G:NHC:A) or C to U (C:G:NHC:A:U) mutations. Together, these biochemical data support a mechanism of action of molnupiravir that is primarily based on RNA mutagenesis mediated via the template strand.
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Affiliation(s)
- Calvin J Gordon
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Egor P Tchesnokov
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Raymond F Schinazi
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Center for AIDS Research, Emory University School of Medicine, and Children's Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Matthias Götte
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada; Li Ka Shing Institute of Virology at University of Alberta, Edmonton, Alberta, Canada.
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23
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Wahl A, Gralinski LE, Johnson CE, Yao W, Kovarova M, Dinnon KH, Liu H, Madden VJ, Krzystek HM, De C, White KK, Gully K, Schäfer A, Zaman T, Leist SR, Grant PO, Bluemling GR, Kolykhalov AA, Natchus MG, Askin FB, Painter G, Browne EP, Jones CD, Pickles RJ, Baric RS, Garcia JV. SARS-CoV-2 infection is effectively treated and prevented by EIDD-2801. Nature 2021; 591:451-457. [PMID: 33561864 PMCID: PMC7979515 DOI: 10.1038/s41586-021-03312-w] [Citation(s) in RCA: 269] [Impact Index Per Article: 89.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 01/29/2021] [Indexed: 12/31/2022]
Abstract
All known recently emerged human coronaviruses likely originated in bats1. Here, we used a single experimental platform based on human lung-only mice (LoM) to demonstrate efficient in vivo replication of all recently emerged human coronaviruses (SARS-CoV, MERS-CoV, SARS-CoV-2) and two highly relevant endogenous pre-pandemic SARS-like bat coronaviruses. Virus replication in this model occurs in bona fide human lung tissue and does not require any type of adaptation of the virus or the host. Our results indicate that bats harbor endogenous coronaviruses capable of direct transmission into humans. Further detailed analysis of pandemic SARS-CoV-2 in vivo infection of LoM human lung tissue showed predominant infection of human lung epithelial cells, including type II pneumocytes present in alveoli and ciliated airway cells. Acute SARS-CoV-2 infection was highly cytopathic and induced a robust and sustained Type I interferon and inflammatory cytokine/chemokine response. Finally, we evaluated a therapeutic and pre-exposure prophylaxis strategy for coronavirus infection. Our results show that therapeutic and prophylactic administration of EIDD-2801, an oral broad spectrum antiviral currently in phase II-III clinical trials, dramatically inhibited SARS-CoV-2 replication in vivo and thus has significant potential for the prevention and treatment of COVID-19.
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Affiliation(s)
- Angela Wahl
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lisa E Gralinski
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Claire E Johnson
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wenbo Yao
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Martina Kovarova
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kenneth H Dinnon
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Hongwei Liu
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Victoria J Madden
- Microscopy Services Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Halina M Krzystek
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chandrav De
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kristen K White
- Microscopy Services Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kendra Gully
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alexandra Schäfer
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tanzila Zaman
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah R Leist
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Paul O Grant
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gregory R Bluemling
- Emory Institute of Drug Development (EIDD), Emory University, Atlanta, GA, USA.,Drug Innovation Ventures at Emory (DRIVE), Atlanta, GA, USA
| | - Alexander A Kolykhalov
- Emory Institute of Drug Development (EIDD), Emory University, Atlanta, GA, USA.,Drug Innovation Ventures at Emory (DRIVE), Atlanta, GA, USA
| | | | - Frederic B Askin
- Department of Pathology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - George Painter
- Emory Institute of Drug Development (EIDD), Emory University, Atlanta, GA, USA.,Drug Innovation Ventures at Emory (DRIVE), Atlanta, GA, USA.,Department of Pharmacology and Chemical Biology, Emory University, Atlanta, GA, USA
| | - Edward P Browne
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,UNC HIV Cure Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Corbin D Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Raymond J Pickles
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Marsico Lung Institute, University of North Carolina at Chapel, Chapel Hill, NC, USA
| | - Ralph S Baric
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Rapidly Emerging Antiviral Drug Discovery Initiative, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - J Victor Garcia
- International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. .,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. .,Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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24
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Abstract
Molnupiravir is an orally available antiviral drug candidate currently in phase III trials for the treatment of patients with COVID-19. Molnupiravir increases the frequency of viral RNA mutations and impairs SARS-CoV-2 replication in animal models and in humans. Here, we establish the molecular mechanisms underlying molnupiravir-induced RNA mutagenesis by the viral RNA-dependent RNA polymerase (RdRp). Biochemical assays show that the RdRp uses the active form of molnupiravir, β-D-N4-hydroxycytidine (NHC) triphosphate, as a substrate instead of cytidine triphosphate or uridine triphosphate. When the RdRp uses the resulting RNA as a template, NHC directs incorporation of either G or A, leading to mutated RNA products. Structural analysis of RdRp-RNA complexes that contain mutagenesis products shows that NHC can form stable base pairs with either G or A in the RdRp active center, explaining how the polymerase escapes proofreading and synthesizes mutated RNA. This two-step mutagenesis mechanism probably applies to various viral polymerases and can explain the broad-spectrum antiviral activity of molnupiravir.
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25
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Lu G, Zhang X, Zheng W, Sun J, Hua L, Xu L, Chu XJ, Ding S, Xiong W. Development of a Simple In Vitro Assay To Identify and Evaluate Nucleotide Analogs against SARS-CoV-2 RNA-Dependent RNA Polymerase. Antimicrob Agents Chemother 2020; 65:e01508-20. [PMID: 33122171 PMCID: PMC7927875 DOI: 10.1128/aac.01508-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Nucleotide analogs targeting viral RNA polymerase have been proved to be an effective strategy for antiviral treatment and are promising antiviral drugs to combat the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. In this study, we developed a robust in vitro nonradioactive primer extension assay to quantitatively evaluate the efficiency of incorporation of nucleotide analogs by SARS-CoV-2 RNA-dependent RNA polymerase (RdRp). Our results show that many nucleotide analogs can be incorporated into RNA by SARS-CoV-2 RdRp and that the incorporation of some of them leads to chain termination. The discrimination values of nucleotide analogs over those of natural nucleotides were measured to evaluate the incorporation efficiency of nucleotide analog by SARS-CoV-2 RdRp. In agreement with the data published in the literature, we found that the incorporation efficiency of remdesivir-TP is higher than that of ATP and incorporation of remdesivir-TP caused delayed chain termination, which can be overcome by higher concentrations of the next nucleotide to be incorporated. Our data also showed that the delayed chain termination pattern caused by remdesivir-TP incorporation is different for different template sequences. Multiple incorporations of remdesivir-TP caused chain termination under our assay conditions. Incorporation of sofosbuvir-TP is very low, suggesting that sofosbuvir may not be very effective in treating SARS-CoV-2 infection. As a comparison, 2'-C-methyl-GTP can be incorporated into RNA efficiently, and the derivative of 2'-C-methyl-GTP may have therapeutic application in treating SARS-CoV-2 infection. This report provides a simple screening method that should be useful for evaluating nucleotide-based drugs targeting SARS-CoV-2 RdRp and for studying the mechanism of action of selected nucleotide analogs.
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Affiliation(s)
- Gaofei Lu
- Global Health Drug Discovery Institute, Beijing, China
| | - Xi Zhang
- Global Health Drug Discovery Institute, Beijing, China
| | - Weinan Zheng
- Global Health Drug Discovery Institute, Beijing, China
| | - Jialei Sun
- Global Health Drug Discovery Institute, Beijing, China
| | - Lan Hua
- Global Health Drug Discovery Institute, Beijing, China
| | - Lan Xu
- Global Health Drug Discovery Institute, Beijing, China
| | - Xin-Jie Chu
- Global Health Drug Discovery Institute, Beijing, China
| | - Sheng Ding
- Global Health Drug Discovery Institute, Beijing, China
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Wen Xiong
- Global Health Drug Discovery Institute, Beijing, China
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26
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Akinci E, Cha M, Lin L, Yeo G, Hamilton MC, Donahue CJ, Bermudez-Cabrera HC, Zanetti LC, Chen M, Barkal SA, Khowpinitchai B, Chu N, Velimirovic M, Jodhani R, Fife JD, Sovrovic M, Cole PA, Davey RA, Cassa CA, Sherwood RI. Elucidation of remdesivir cytotoxicity pathways through genome-wide CRISPR-Cas9 screening and transcriptomics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.08.27.270819. [PMID: 32869031 PMCID: PMC7457617 DOI: 10.1101/2020.08.27.270819] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The adenosine analogue remdesivir has emerged as a front-line antiviral treatment for SARS-CoV-2, with preliminary evidence that it reduces the duration and severity of illness1.Prior clinical studies have identified adverse events1,2, and remdesivir has been shown to inhibit mitochondrial RNA polymerase in biochemical experiments7, yet little is known about the specific genetic pathways involved in cellular remdesivir metabolism and cytotoxicity. Through genome-wide CRISPR-Cas9 screening and RNA sequencing, we show that remdesivir treatment leads to a repression of mitochondrial respiratory activity, and we identify five genes whose loss significantly reduces remdesivir cytotoxicity. In particular, we show that loss of the mitochondrial nucleoside transporter SLC29A3 mitigates remdesivir toxicity without a commensurate decrease in SARS-CoV-2 antiviral potency and that the mitochondrial adenylate kinase AK2 is a remdesivir kinase required for remdesivir efficacy and toxicity. This work elucidates the cellular mechanisms of remdesivir metabolism and provides a candidate gene target to reduce remdesivir cytotoxicity.
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Affiliation(s)
- Ersin Akinci
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Department of Agricultural Biotechnology, Faculty of Agriculture, Akdeniz University, Antalya, 07070, Turkey
| | - Minsun Cha
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Lin Lin
- Hubrecht Institute, 3584 CT Utrecht, the Netherlands
| | - Grace Yeo
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Marisa C Hamilton
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Callie J Donahue
- Department of Microbiology, National Emerging Infectious Disease Laboratories, Boston University Medical Campus, Boston, MA 02118, USA
| | - Heysol C Bermudez-Cabrera
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Larissa C Zanetti
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Hospital Israelita Albert Einstein, São Paulo, SP 05652-900, Brazil
| | - Maggie Chen
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Sammy A Barkal
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Benyapa Khowpinitchai
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Nam Chu
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Minja Velimirovic
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Rikita Jodhani
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - James D Fife
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Miha Sovrovic
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Philip A Cole
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Robert A Davey
- Department of Microbiology, National Emerging Infectious Disease Laboratories, Boston University Medical Campus, Boston, MA 02118, USA
| | - Christopher A Cassa
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Richard I Sherwood
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
- Hubrecht Institute, 3584 CT Utrecht, the Netherlands
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27
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Toots M, Plemper RK. Next-generation direct-acting influenza therapeutics. Transl Res 2020; 220:33-42. [PMID: 32088166 PMCID: PMC7102518 DOI: 10.1016/j.trsl.2020.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/22/2020] [Accepted: 01/28/2020] [Indexed: 12/16/2022]
Abstract
Influenza viruses are a major threat to human health globally. In addition to further improving vaccine prophylaxis, disease management through antiviral therapeutics constitutes an important component of the current intervention strategy to prevent advance to complicated disease and reduce case-fatality rates. Standard-of-care is treatment with neuraminidase inhibitors that prevent viral dissemination. In 2018, the first mechanistically new influenza drug class for the treatment of uncomplicated seasonal influenza in 2 decades was approved for human use. Targeting the PA endonuclease subunit of the viral polymerase complex, this class suppresses viral replication. However, the genetic barrier against viral resistance to both drug classes is low, pre-existing resistance is observed in circulating strains, and resistant viruses are pathogenic and transmit efficiently. Addressing the resistance problem has emerged as an important objective for the development of next-generation influenza virus therapeutics. This review will discuss the status of influenza therapeutics including the endonuclease inhibitor baloxavir marboxil after its first year of clinical use and evaluate a subset of direct-acting antiviral candidates in different stages of preclinical and clinical development.
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Affiliation(s)
- Mart Toots
- Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia.
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