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Trade names | Tembexa |
Other names | CMX001; Cidofovir-HDP; hexadecyloxypropyl-cidofovir |
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Routes of administration | By mouth |
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Formula | C27H52N3O7P |
Molar mass | 561.701 g·mol−1 |
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Brincidofovir, sold under the brand name Tembexa, is an antiviral drug used to treat smallpox. Brincidofovir is a prodrug of cidofovir. [4] Conjugated to a lipid, the compound is designed to release cidofovir intracellularly, allowing for higher intracellular and lower plasma concentrations of cidofovir, effectively increasing its activity against dsDNA viruses, as well as oral bioavailability. [5]
The most common side effects include diarrhea, nausea, vomiting, and abdominal pain. [3] It carries an FDA-mandated black box warning of an increased risk of death with extended use. [6] [7] Brincidofovir was approved for medical use in the United States in June 2021.
Brincidofovir is indicated for the treatment of human smallpox disease caused by the variola virus. [3] [8]
Brincidofovir is a prodrug that is composed of cidofovir conjugated with a lipid molecule. The lipid aspect of the molecule takes on the action of endogenous lysophosphatidyl choline, which then is able to enter cells in the body which are infected with smallpox. [9] Once the infected cell takes in the drug, the drug cleaves to generate cidofovir. Cidofovir is then consequently phosphorylated to yield cidofovir diphosphate, which is the active drug. Cidofovir diphosphate inhibits the variola virus' DNA polymerase-mediated DNA synthesis. The drug acts as an acyclic nucleotide and incorporates itself into the viral DNA chain, which then stops viral DNA synthesis. [10]
The oral bioavailability of Brincidofovir is 13.4% as a tablet and 16.8% in a suspension. [9] The metabolism of the drug is as such: once the drug enters the target infected cell, Brincidofovir's phosphodiester bond is then hydrolyzed to generate cidofovir which is then phosphorylated to the active cidofovir diphosphate. The volume of distribution of the drug is 1230 L. [9]
Because smallpox is eradicated, the effectiveness of brincidofovir was studied in animals infected with viruses that are closely related to the variola virus. [3] Effectiveness was determined by measuring animals' survival at the end of the studies. [3]
Safety information to support approval of brincidofovir was derived from clinical trials of the drug for a non-smallpox indication, primarily from patients who received hematopoietic stem cell transplants. [3]
The U.S. Food and Drug Administration (FDA) granted the application for brincidofovir priority review, fast track, and orphan drug designations. [3] The FDA approved brincidofovir under the agency's Animal Rule, which allows findings from adequate and well-controlled animal efficacy studies to serve as the basis of an approval when it is not feasible or ethical to conduct efficacy trials in humans. [3]
Brincidofovir (CMX001) was the subject of widespread social media campaigning in 2014, which was then picked up by national news sources about a boy with an adenovirus infection following a bone marrow transplant. [11] The family requested legal access to the still-unapproved drug outside of any clinical trial, and Chimerix initially denied the request. After a short and intense media campaign, Chimerix got permission from the FDA to start a limited open-label trial which allowed the boy to receive the drug. [11] This media event sparked a debate on the ethics of using social media, the allocation of limited resources of a small company, and the emphasis on the individual over the group. The new use of any drug has the potential to interfere with the process to get the drug approved and widely marketed, through means such as consuming limited staff time that may be needed elsewhere – staff time that has the potential to save thousands of lives in the long-term, rather than one life now – overwhelming manufacturing capabilities, or by causing adverse effects or even death. [11] These adverse events are more likely during these programs, because the people seeking access are usually much sicker than most, and problems experienced by these people can result in an unfavorable and inaccurate perception of the drug's safety profile. [11] In this case, the boy recovered from the infection in 2014, and died in 2016 from complications of cancer. [12]
Brincidofovir is one of several experimental drugs administered to a small number of patients to treat Ebola virus disease during the 2014 outbreak. The WHO published a report on the ethics of using unregistered interventions to treat Ebola, where they concluded that "In the particular context of the current Ebola outbreak in West Africa, it is ethically acceptable to offer unproven interventions that have shown promising results in the laboratory and in animal models but have not yet been evaluated for safety and efficacy in humans as potential treatment or prevention." [13]
Brincidofovir is under investigation for the treatment of cytomegalovirus, adenovirus, poxvirus, and ebolavirus infections. [14] It has been used off-label for the treatment of monkeypox. [15]
As of 2014 [update] , brincidofovir is in Phase III clinical trials for use in humans against cytomegalovirus and adenovirus. Preliminary safety data from a database of 1000 patients supported progression into later phase trials, [16] Chimerix announced in December 2015 that the Phase III trials for use of the drug in preventing cytomegalovirus infection in stem cell transplant patients had failed, and in February 2016 shut down two other late-stage trials for use of the drug in preventing infection after kidney transplants. Brincidofovir is not yet FDA approved for adenovirus or cytomegalovirus due to lack of efficacy in clinical trials. [17] In a trial of brincidofovir for patients with CMV brincidofovir was associated with a 15.5% week 24 all-cause mortality compared with 10.1% among placebo recipients. Additionally brincidofovir was associated with increased serious adverse events (57.1% versus 37.6%) compared with placebo. [17] Brincidofovir was initially offered via an FDA expanded access trial; however as of 9 May 2019, Chimerix discontinued clinical trials of brincidofovir for the treatment of adenovirus and discontinued the expanded access program in 2019. [18]
After initial studies by the Centers for Disease Control and Prevention (CDC, Atlanta, Georgia, US) in cell culture models, [19] on 6 October 2014, Chimerix received an FDA authorization for emergency investigational new drug applications of brincidofovir for the treatment of Ebola virus disease. Brincidofovir was administered to the first patient diagnosed in the Ebola virus disease outbreak in the US in 2014. [20] [21] The patient was given the drug starting six days after hospital admission when he was already critically ill; he died four days later. [22] [23] Brincidofovir was also given to Ebola patient Ashoka Mukpo at the Nebraska Medical Center, who had developed the disease and then was pronounced Ebola-free and released from the center on 22 October 2014. [24]
In October 2014, Chimerix reported it had been given approval by the FDA to start Phase 2 trials in patients infected with ebolaviruses for brincidofovir's safety, tolerability, and efficacy. [25] Organised by a team of scientists at the University of Oxford, including Peter Horby, Jake Dunning, Laura Merson and Trudie Lang, [26] a trial commenced during January 2015 in Liberia, [27] but was subsequently discontinued. Because of a lack of suitable subjects in Liberia, Oxford University and Médecins Sans Frontières planned to extend the trial to Sierra Leone, where there were still Ebola cases; but on 30 January 2015, the manufacturer decided to withdraw support for the trial and end discussion of future trials. [28] [29]
In animal trials brincidofovir has shown activity against cytomegalovirus, adenoviruses, BK virus, poxvirus es, and herpes simplex viruses. [4] [30] Brincidofovir appears to have potential for the treatment of Ebola virus disease, which is somewhat paradoxical, as ebolaviruses are RNA viruses and thus do not contain DNA as the above-mentioned viruses. [19] [31]
Ribavirin, also known as tribavirin, is an antiviral medication used to treat RSV infection, hepatitis C and some viral hemorrhagic fevers. For hepatitis C, it is used in combination with other medications such as simeprevir, sofosbuvir, peginterferon alfa-2b or peginterferon alfa-2a. It can also be used for viral hemorrhagic fevers, specifically for Lassa fever, Crimean–Congo hemorrhagic fever, and Hantavirus infection with exceptions for Ebola or Marburg infections. Ribavirin is usually taken orally or inhaled. Despite widespread usage, it has faced scrutiny in 2010 because of lack of efficacy in treating viral infections as it has historically been prescribed for.
Cidofovir, brand name Vistide, is a topical or injectable antiviral medication primarily used as a treatment for cytomegalovirus (CMV) retinitis in people with AIDS.
Ganciclovir, sold under the brand name Cytovene among others, is an antiviral medication used to treat cytomegalovirus (CMV) infections.
Orthopoxvirus is a genus of viruses in the family Poxviridae and subfamily Chordopoxvirinae. Vertebrates, including mammals and humans, and arthropods serve as natural hosts. There are 12 species in this genus. Diseases associated with this genus include smallpox, cowpox, horsepox, camelpox, and mpox. The most widely known member of the genus is Variola virus, which causes smallpox. It was eradicated globally by 1977, through the use of Vaccinia virus as a vaccine. The most recently described species is the Alaskapox virus, first isolated in 2015.
Foscarnet (phosphonomethanoic acid), known by its brand name Foscavir, is an antiviral medication which is primarily used to treat viral infections involving the Herpesviridae family. It is classified as a pyrophosphate analog DNA polymerase inhibitor. Foscarnet is the conjugate base of a chemical compound with the formula HO2CPO3H2 (Trisodium phosphonoformate).
Human betaherpesvirus 5, also called human cytomegalovirus (HCMV,HHV-5), is a species of virus in the genus Cytomegalovirus, which in turn is a member of the viral family known as Herpesviridae or herpesviruses. It is also commonly called CMV. Within Herpesviridae, HCMV belongs to the Betaherpesvirinae subfamily, which also includes cytomegaloviruses from other mammals. CMV is a double-stranded DNA virus.
Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is indicated for the treatment of infection by Cryptosporidium parvum and Giardia lamblia in immunocompetent individuals and has been repurposed for the treatment of influenza. Nitazoxanide has also been shown to have in vitro antiparasitic activity and clinical treatment efficacy for infections caused by other protozoa and helminths; evidence as of 2014 suggested that it possesses efficacy in treating a number of viral infections as well.
A Cytomegalovirus vaccine is a vaccine to prevent cytomegalovirus (CMV) infection or curb virus re-activation in persons already infected. Challenges in developing a vaccine include adeptness of CMV in evading the immune system and limited animal models. As of 2018 no such vaccine exists, although a number of vaccine candidates are under investigation. They include recombinant protein, live attenuated, DNA and other vaccines.
Maribavir, sold under the brand name Livtencity, is an antiviral medication that is used to treat post-transplant cytomegalovirus (CMV). Maribavir is a cytomegalovirus pUL97 kinase inhibitor that works by preventing the activity of human cytomegalovirus enzyme pUL97, thus blocking virus replication.
Tecovirimat, sold under the brand name Tpoxx among others, is an antiviral medication with activity against orthopoxviruses such as smallpox and mpox. In 2018 it was the first antipoxviral drug approved in the United States.
Pritelivir is a direct-acting antiviral drug in development for the treatment of herpes simplex virus infections (HSV). This is particularly important in immune compromised patients. It is currently in Phase III clinical development by the German biopharmaceutical company AiCuris Anti-infective Cures AG. US FDA granted fast track designation for pritelivir in 2017 and breakthrough therapy designation 2020.
Letermovir is an antiviral drug for the treatment of cytomegalovirus (CMV) infections. It has been tested in CMV infected patients with allogeneic stem cell transplants and may also be useful for other patients with a compromised immune system such as those with organ transplants or HIV infections. The drug was initially developed by the anti-infective division at Bayer, which became AiCuris Anti-infective Cures AG through a spin-out and progressed the development to end of Phase 2 before the project was sold to Merck & Co for Phase 3 development and approval.
Favipiravir, sold under the brand name Avigan among others, is an antiviral medication used to treat influenza in Japan. It is also being studied to treat a number of other viral infections, including SARS-CoV-2. Like the experimental antiviral drugs T-1105 and T-1106, it is a pyrazinecarboxamide derivative.
ZMapp is an experimental biopharmaceutical medication comprising three chimeric monoclonal antibodies under development as a treatment for Ebola virus disease. Two of the three components were originally developed at the Public Health Agency of Canada's National Microbiology Laboratory (NML), and the third at the U.S. Army Medical Research Institute of Infectious Diseases; the cocktail was optimized by Gary Kobinger, a research scientist at the NML and underwent further development under license by Mapp Biopharmaceutical. ZMapp was first used on humans during the Western African Ebola virus epidemic, having only been previously tested on animals and not yet subjected to a randomized controlled trial. The National Institutes of Health (NIH) ran a clinical trial starting in January 2015 with subjects from Sierra Leone, Guinea, and Liberia aiming to enroll 200 people, but the epidemic waned and the trial closed early, leaving it too statistically underpowered to give a meaningful result about whether ZMapp worked.
Ebola vaccines are vaccines either approved or in development to prevent Ebola. As of 2022, there are only vaccines against the Zaire ebolavirus. The first vaccine to be approved in the United States was rVSV-ZEBOV in December 2019. It had been used extensively in the Kivu Ebola epidemic under a compassionate use protocol. During the early 21st century, several vaccine candidates displayed efficacy to protect nonhuman primates against lethal infection.
There is a cure for the Ebola virus disease that is currently approved for market the US government has inventory in the Strategic National Stockpile. For past and current Ebola epidemics, treatment has been primarily supportive in nature.
Ansuvimab, sold under the brand name Ebanga, is a monoclonal antibody medication for the treatment of Zaire ebolavirus (Ebolavirus) infection.
COVID-19 drug development is the research process to develop preventative therapeutic prescription drugs that would alleviate the severity of coronavirus disease 2019 (COVID-19). From early 2020 through 2021, several hundred drug companies, biotechnology firms, university research groups, and health organizations were developing therapeutic candidates for COVID-19 disease in various stages of preclinical or clinical research, with 419 potential COVID-19 drugs in clinical trials, as of April 2021.
Atoltivimab/maftivimab/odesivimab, sold under the brand name Inmazeb, is a fixed-dose combination of three monoclonal antibodies for the treatment of Zaire ebolavirus. It contains atoltivimab, maftivimab, and odesivimab-ebgn and was developed by Regeneron Pharmaceuticals.
A viral vector vaccine is a vaccine that uses a viral vector to deliver genetic material (DNA) that can be transcribed by the recipient's host cells as mRNA coding for a desired protein, or antigen, to elicit an immune response. As of April 2021, six viral vector vaccines, four COVID-19 vaccines and two Ebola vaccines, have been authorized for use in humans.