Merck and Ridgeback Biotherapeutics Provide Update on Progress of Clinical Development Program for Molnupiravir, an Investigational Oral Therapeutic for the Treatment of Mild-to-Moderate COVID-19

Merck, News Release, NCT04575584, Apr 2021

https://c19early.org/merckmovein.html

News release reporting that the trial of molnupiravir with hospitalized patients (NCT04575584 (history)) has been discontinued because data indicates it is unlikely to demonstrate a clinical benefit in hospitalized patients. Results are not available yet. Interim results for the trial with outpatients show positive dose-dependent results for viral clearance.

Potential risks of molnupiravir include the creation of dangerous variants, and mutagenicity, carcinogenicity, teratogenicity, and embryotoxicity1-14. Multiple analyses have identified variants potentially created by molnupiravir15-19.

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1. Swanstrom et al., Lethal mutagenesis as an antiviral strategy, Science, doi:10.1126/science.abn0048.science.org, doi.org.

2. Hadj Hassine et al., Lethal Mutagenesis of RNA Viruses and Approved Drugs with Antiviral Mutagenic Activity, Viruses, doi:10.3390/v14040841.mdpi.com, doi.org.

3. Shum, C., An investigational study into the drug-associated mutational signature in SARS-CoV-2 viruses, The University of Hong Kong, PhD Thesis, hub.hku.hk/handle/10722/344396.hku.hk.

4. Waters et al., Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: the special case of molnupiravir, Environmental and Molecular Mutagenesis, doi:10.1002/em.22471.wiley.com, doi.org.

5. Huntsman, M., An assessment of the reproductive toxicity of the anti-COVID-19 drug molnupiravir using stem cell-based embryo models, Master's Thesis, scholarspace.manoa.hawaii.edu/items/cd11342c-b4dc-44c0-8b44-ce6e3369c40b.hawaii.edu.

6. Zibat et al., N4-hydroxycytidine, the active compound of Molnupiravir, promotes SARS-CoV-2 mutagenesis and escape from a neutralizing nanobody, iScience, doi:10.1016/j.isci.2023.107786.sciencedirect.com, doi.org.

7. Shiraki et al., Convenient screening of the reproductive toxicity of favipiravir and antiviral drugs in Caenorhabditis elegans, Heliyon, doi:10.1016/j.heliyon.2024.e35331.sciencedirect.com, doi.org.

8. Gruber et al., Molnupiravir increases SARS‐CoV‐2 genome diversity and complexity: A case‐control cohort study, Journal of Medical Virology, doi:10.1002/jmv.29642.wiley.com, doi.org.

9. Marikawa et al., An active metabolite of the anti-COVID-19 drug molnupiravir impairs mouse preimplantation embryos at clinically relevant concentrations, Reproductive Toxicology, doi:10.1016/j.reprotox.2023.108475.sciencedirect.com, doi.org.

10. Rahman, M., Elucidation of the DNA repair mechanisms involved in the repair of DNA damage caused by the Arabinosides and Anti-COVID-19 drugs, tokyo-metro-u.repo.nii.ac.jp/records/2000972.ac.jp.

11. Zhou et al., β-D-N4-hydroxycytidine Inhibits SARS-CoV-2 Through Lethal Mutagenesis But Is Also Mutagenic To Mammalian Cells, The Journal of Infectious Diseases, doi:10.1093/infdis/jiab247.oup.com, doi.org.

12. Chamod et al., Molnupiravir Metabolite--N4-hydroxycytidine Causes Cytotoxicity and DNA Damage in Mammalian Cells in vitro: N4-hydroxycytidine Induced Cytotoxicity DNA Damage, Asian Medical Journal and Alternative Medicine, 23:3, asianmedjam.com/index.php/amjam/article/view/1448.asianmedjam.com.

13. Standing et al., Randomized controlled trial of molnupiravir SARS-CoV-2 viral and antibody response in at-risk adult outpatients, Nature Communications, doi:10.1038/s41467-024-45641-0.nature.com, doi.org.

14. Mori et al., Reactive oxygen species-mediated cytotoxic and DNA-damaging mechanism of N4-hydroxycytidine, a metabolite of the COVID-19 therapeutic drug molnupiravir, Free Radical Research, doi:10.1080/10715762.2025.2469738.tandfonline.com, doi.org.

15. Focosi et al., The fitness of molnupiravir-signed SARS-CoV-2 variants: imputation analysis based on prescription counts and GISAID analyses by country, Intervirology, doi:10.1159/000540282.karger.com, doi.org.

16. Sanderson et al., A molnupiravir-associated mutational signature in global SARS-CoV-2 genomes, Nature, doi:10.1038/s41586-023-06649-6.nature.com, doi.org.

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18. Kosakovsky Pond et al., Anti-COVID drug accelerates viral evolution, Nature, doi:10.1038/d41586-023-03248-3.nature.com, doi.org.

19. twitter.com, twitter.com/LongDesertTrain/status/1597353291868155906.twitter.com/LongDesertTrain/status/1597353291868155906.

Merck et al., 15 Apr 2021, preprint, 1 author, trial NCT04575584 (history).

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