Oral Brincidofovir Therapy for Monkeypox Outbreak: A Focused Review on the Therapeutic Potential, Clinical Studies, Patent Literature, and Prospects

Novel derivatives of brincidofovir and (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine inhibit orthopoxviruses and human adenoviruses more potently than brincidofovir

Brincidofovir (BCV) and tecovirimat are the only two chemical drugs that have been approved to treat smallpox and can be requested for monkeypox (Mpox) treatment through a single-patient Emergency Investigational New Drug (EIND) application. Disappointedly, the efficacy of tecovirimat manifested in recent clinical trials is far from being satisfactory, while the clinical efficacy of BCV is still inconclusive. Given that monkeypox virus (MPXV), variola and other emerging orthopoxviruses are posing serious threats to global health, it is urgent to develop better therapeutics. In this study, we tested the antiviral effects of three novel prodrugs, which were designed based on previously reported parent drugs, either (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine ((S)-HPMPC, cidofovir) or (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine ((S)-HPMPA). We found that one of the (S)-HPMPA-based prodrugs, ODE-(S)-HPMPA formate, exhibited significantly better anti-orthopoxvirus activity than BCV both in vitro and in vivo, which also inhibited human adenovirus type 2 and type 21 more efficiently than BCV. Most strikingly, the EC50 and EC90 of ODE-(S)-HPMPA formate against MPXV were more than 40-fold lower than those of BCV. In contrast, we observed that the anti-herpes simplex virus type 1 (HSV-1) activities of the (S)-HPMPA-based prodrugs were less effective than those of the cidofovir-based prodrugs (BCV and BCV formate), especially in vivo. Moreover, we showed for the first time that cytidine and adenine analog combined therapies could provide mice with complete protection against lethal challenges of both vaccinia and HSV-1. Collectively, we propose that both the ODE-(S)-HPMPA formate and the BCV/ODE-(S)-HPMPA formate combination are worth further investigations for their potential clinical applications.

Monkeypox: Origin, Transmission, Clinical Manifestations, Prevention, and Therapeutic Options

Monkeypox is a rapidly spreading transmissible disease induced by the monkeypox virus (MPXV), a major public health problem worldwide. The origin of monkeypox might be tracked to the continent of Africa, where it first afflicted primate species prior to spreading to the world. Severe health issues for the public have been raised as a result of the disease's current breakouts in nonendemic areas and its subsequent dissemination to several nations throughout the globe. Monkeypox spreads by having contact with infected creatures or people, as well as respiratory droplets and contaminated things. Symptoms of monkeypox in young children and adults are different. While the symptoms are similar to smallpox, monkeypox has a reduced mortality rate. Proper diagnosis, suitable care, and focused preventative efforts all depend on becoming cognizant of those distinctions. Numerous promising therapeutic approaches have been recently investigated. Antiviral drugs such as tecovirimat, cidofovir, and brincidofovir, which were initially developed to treat smallpox, were found to have been effective in treating MPXV cases. Moreover, vaccinations continue to be an important preventative step. The purpose of this article is to offer the most recent and thorough information available on monkeypox, including its possible causes, modes of transfer, and potential treatments. By identifying the distinct forms of monkeypox and exploring potential treatment options, this work contributes to the ongoing battle against MPXVs and the management of this novel viral disease. To stop the propagation of monkeypox, greater research and communication are needed to provide stronger treatments and effective vaccinations.

Treatment efficacy of cidofovir and brincidofovir against clade II Monkeypox virus isolates

While historically confined to endemic areas, Monkeypox virus (MPXV) infection has increasingly garnered international attention due to sporadic outbreaks in non-endemic countries in the last two decades and its potential for human-to-human transmission. In 2022, a multi-country outbreak of mpox disease was declared by the World Health Organization (WHO) and nearly 100 000 mpox cases have been reported since the beginning of this pandemic. The clade II variant of the virus appears to be responsible for the vast majority of these infections. While there are no antiviral drugs currently approved to treat mpox specifically, the use of tecovirimat (TPOXX®) and brincidofovir (Tembexa®) is recommended by the Centers for Disease Control and Prevention (CDC) for compassionate use in severe mpox cases, since both are FDA-approved for the treatment of the closely related smallpox disease. Given the emergence of multiple tecovirimat-resistant infections, we aimed to evaluate the treatment efficacy of brincidofovir and its active compound, cidofovir, against MPXV clade II strains. Following intranasal infection, we show that cidofovir and brincidofovir can strongly reduce the viral replication of MPXV clade IIa and IIb viruses in the respiratory tract of susceptible mice when administered systemically and orally, respectively. The high antiviral activity of both compounds against historical and currently circulating MPXV strains supports their therapeutic potential for clinical application.

Unachieved antiviral strategies with acyclic nucleoside phosphonates: Dedicated to the memory of dr. Salvatore "Sam" Joseph Enna

Many acyclic nucleoside phosphonates such as cidofovir, adefovir dipivoxil, tenofovir disoproxil fumarate, and tenofovir alafenamide have been marketed for the treatment or prophylaxis of infectious diseases. Here, this review highlights potent acyclic nucleoside phosphonates for their potential in the treatment of retrovirus (e.g., human immunodeficiency virus) and DNA virus (e.g., adeno-, papilloma-, herpes- and poxvirus) infections. If properly assessed and/or optimized, some potent acyclic nucleoside phosphonates can be possibly applied in the control of current and emerging infectious diseases.

Human monkeypox virus: Epidemiologic review and research progress in diagnosis and treatment

Monkeypox virus (MPXV) is responsible for causing a zoonotic disease called monkeypox (mpox), which sporadically infects humans in West and Central Africa. It first infected humans in 1970 and, along with the variola virus, belongs to the genus Orthopoxvirus in the poxvirus family. Since the World Health Organization declared the MPXV outbreak a "Public Health Emergency of International Concern" on July 23, 2022, the number of infected patients has increased dramatically. To control this epidemic and address this previously neglected disease, MPXV needs to be better understood and reevaluated. In this review, we cover recent research on MPXV, including its genomic and pathogenic characteristics, transmission, mutations and mechanisms, clinical characteristics, epidemiology, laboratory diagnosis, and treatment measures, as well as prevention of MPXV infection in light of the 2022 and 2023 global outbreaks. The 2022 MPXV outbreak has been primarily associated with close intimate contact, including sexual activity, with most cases diagnosed among men who have sex with men. The incubation period of MPXV infection usually lasts from 6 to 13 days, and symptoms include fever, muscle pains, headache, swollen lymph nodes, and a characteristic painful rash, including several stages, such as macules, papules, blisters, pustules, scabs, and scab shedding involving the genitals and anus. Polymerase chain reaction (PCR) is usually used to detect MPXV in skin lesion material. Treatment includes supportive care, antivirals, and intravenous vaccinia immune globulin. Smallpox vaccines have been designed with four givens emergency approval for use against MPXV infection.

Mpox (formerly monkeypox): pathogenesis, prevention, and treatment

In 2022, a global outbreak of Mpox (formerly monkeypox) occurred in various countries across Europe and America and rapidly spread to more than 100 countries and regions. The World Health Organization declared the outbreak to be a public health emergency of international concern due to the rapid spread of the Mpox virus. Consequently, nations intensified their efforts to explore treatment strategies aimed at combating the infection and its dissemination. Nevertheless, the available therapeutic options for Mpox virus infection remain limited. So far, only a few numbers of antiviral compounds have been approved by regulatory authorities. Given the high mutability of the Mpox virus, certain mutant strains have shown resistance to existing pharmaceutical interventions. This highlights the urgent need to develop novel antiviral drugs that can combat both drug resistance and the potential threat of bioterrorism. Currently, there is a lack of comprehensive literature on the pathophysiology and treatment of Mpox. To address this issue, we conducted a review covering the physiological and pathological processes of Mpox infection, summarizing the latest progress of anti-Mpox drugs. Our analysis encompasses approved drugs currently employed in clinical settings, as well as newly identified small-molecule compounds and antibody drugs displaying potential antiviral efficacy against Mpox. Furthermore, we have gained valuable insights from the process of Mpox drug development, including strategies for repurposing drugs, the discovery of drug targets driven by artificial intelligence, and preclinical drug development. The purpose of this review is to provide readers with a comprehensive overview of the current knowledge on Mpox.

Antivirals against Monkeypox (Mpox) in Humans: An Updated Narrative Review

As of 29 August 2023, a total of 89,596 confirmed cases of Mpox (monkeypox) have been documented across 114 countries worldwide, with 157 reported fatalities. The Mpox outbreak that transpired in 2022 predominantly affected young men who have sex with men (MSM). While most cases exhibited a mild clinical course, individuals with compromised immune systems, particularly those living with HIV infection and possessing a CD4 count below 200 cells/mm3, experienced a more severe clinical trajectory marked by heightened morbidity and mortality. The approach to managing Mpox is primarily symptomatic and supportive. However, in instances characterized by severe or complicated manifestations, the utilization of antiviral medications becomes necessary. Despite tecovirimat's lack of official approval by the FDA for treating Mpox in humans, a wealth of positive clinical experiences exists, pending the outcomes of ongoing clinical trials. Brincidofovir and cidofovir have also been administered in select cases due to the unavailability of tecovirimat. Within the scope of this narrative review, our objective was to delve into the clinical attributes of Mpox and explore observational studies that shed light on the utilization of these antiviral agents.

Clinical Predictors of Monkeypox Diagnosis: A Case-Control Study in a Nonendemic Region during the 2022 Outbreak

Monkeypox (Mpox) is an emerging zoonotic disease with the potential for severe complications. Early identification and diagnosis are essential to prompt treatment, control its spread, and reduce the risk of human-to-human transmission. This study aimed to develop a clinical diagnostic tool and describe the clinical and sociodemographic features of 19 PCR-confirmed Mpox cases during an outbreak in a nonendemic region of northwestern Mexico. The median age of patients was 35 years, and most were male. Mpox-positive patients commonly reported symptoms such as fever, lumbago, and asthenia, in addition to experiencing painful ulcers and a high frequency of HIV infection among people living with HIV (PLWH). Two diagnostic models using logistic regression were devised, with the best model exhibiting a prediction accuracy of 0.92 (95% CI: 0.8-1), a sensitivity of 0.86, and a specificity of 0.93. The high predictive values and accuracy of the top-performing model highlight its potential to significantly improve early Mpox diagnosis and treatment in clinical settings, aiding in the control of future outbreaks.

Viroporins of Mpox Virus

Mpox or monkeypox virus (MPXV) belongs to the subclass of Poxviridae and has emerged recently as a global threat. With a limited number of anti-viral drugs available for this new virus species, it is challenging to thwart the illness it begets. Therefore, characterizing new drug targets in the virus may prove advantageous to curbing the disease. Since channels as a family are excellent drug targets, we have sought to identify viral ion channels for this virus, which are instrumental in formulating channel-blocking anti-viral drugs. Bioinformatics analyses yielded eight transmembranous proteins smaller or equal to 100 amino acids in length. Subsequently, three independent bacteria-based assays have pointed to five of the eight proteins that exhibit ion channel activity. Finally, we propose a tentative structure of four ion channels from their primary amino acid sequences, employing AlphaFold2 and molecular dynamic simulation methods. These results may represent the first steps in characterizing MPXV viroporins en route to developing blockers that inhibit their function.

Patent profile for the approved and in clinical trials Mpox vaccines

Mpox disease was reported in 110 countries since May 2022, with 88,026 cases and 148 deaths by 21 June 2023. Although some drugs were already approved for Mpox treatment, the available smallpox vaccines can provide 85% cross-prevention, but there are no scientific publications describing the patent portfolio for Mpox vaccines. This paper aims to contribute to the identification of the status of the smallpox vaccine patents now applied for Mpox. We retrieved ten vaccines, but only a few had a patent portfolio and one under patent litigation processes in three continents. Also, no specific Mpox vaccine was retrieved and, in this sense, technological monitoring studies should be performed to provide a future vision regarding Mpox prophylaxis.

VP37 Protein Inhibitors for Mpox Treatment: Highlights on Recent Advances, Patent Literature, and Future Directions

Monkeypox disease (Mpox) has threatened humankind worldwide since mid-2022. The Mpox virus (MpoxV) is an example of Orthopoxviruses (OPVs), which share similar genomic structures. A few treatments and vaccines are available for Mpox. OPV-specific VP37 protein (VP37P) is a target for developing drugs against Mpox and other OPV-induced infections such as smallpox. This review spotlights the existing and prospective VP37P inhibitors (VP37PIs) for Mpox. The non-patent literature was collected from PubMed, and the patent literature was gathered from free patent databases. Very little work has been carried out on developing VP37PIs. One VP37PI (tecovirimat) has already been approved in Europe to treat Mpox, while another drug, NIOCH-14, is under clinical trial. Developing tecovirimat/NIOCH-14-based combination therapies with clinically used drugs demonstrating activity against Mpox or other OPV infections (mitoxantrone, ofloxacin, enrofloxacin, novobiocin, cidofovir, brincidofovir, idoxuridine, trifluridine, vidarabine, fialuridine, adefovir, imatinib, and rifampicin), immunity boosters (vitamin C, zinc, thymoquinone, quercetin, ginseng, etc.), and vaccines may appear a promising strategy to fight against Mpox and other OPV infections. Drug repurposing is also a good approach for identifying clinically useful VP37PIs. The dearth in the discovery process of VP37PIs makes it an interesting area for further research. The development of the tecovirimat/NIOCH-14-based hybrid molecules with certain chemotherapeutic agents looks fruitful and can be explored to obtain new VP37PI. It would be interesting and challenging to develop an ideal VP37PI concerning its specificity, safety, and efficacy.