Brincidofovir inhibits polyomavirus infection in vivo.

Polyomaviruses are species-specific DNA viruses that can cause disease in immunocompromised individuals. Despite their role as the causative agents for several diseases, there are no currently approved antivirals for treating polyomavirus infection. Brincidofovir (BCV) is an antiviral approved for the treatment of poxvirus infections and has shown activity against other double-stranded DNA viruses. In this study, we tested the efficacy of BCV against polyomavirus infection in vitro and in vivo using mouse polyomavirus (MuPyV). BCV inhibited virus production in primary mouse kidney cells and brain cortical cells. BCV treatment of cells transfected with MuPyV genomic DNA resulted in a reduction in virus levels, indicating that viral inhibition occurs post-entry. Although in vitro BCV treatment had a limited effect on viral DNA and RNA levels, drug treatment was associated with a reduction in viral protein, raising the possibility that BCV acts post-transcriptionally to inhibit MuPyV infection. In mice, BCV treatment was well tolerated, and prophylactic treatment resulted in a reduction in viral DNA levels and a potent suppression of infectious virus production in the kidney and brain. In mice with chronic polyomavirus infection, therapeutic administration of BCV decreased viremia and reduced infection in the kidney. These data demonstrate that BCV exerts antiviral activity against polyomavirus infection in vivo, supporting further investigation into the use of BCV to treat clinical polyomavirus infections. IMPORTANCE: Widespread in the human population and able to persist asymptomatically for the life of an individual, polyomavirus infections cause a significant disease burden in the immunocompromised. Individuals undergoing immune suppression, such as kidney transplant patients or those treated for autoimmune diseases, are particularly at high risk for polyomavirus-associated diseases. Because no antiviral agent exists for treating polyomavirus infections, management of polyomavirus-associated diseases typically involves reducing or discontinuing immunomodulatory therapy. This can be perilous due to the risk of transplant rejection and the potential development of adverse immune reactions. Thus, there is a pressing need for the development of antivirals targeting polyomaviruses. Here, we investigate the effects of brincidofovir, an FDA-approved antiviral, on polyomavirus infection in vivo using mouse polyomavirus. We show that the drug is well-tolerated in mice, reduces infectious viral titers, and limits viral pathology, indicating the potential of brincidofovir as an anti-polyomavirus therapeutic.

Treatment and Vaccination for Smallpox and Monkeypox.

The smallpox infection with the variola virus was one of the most fatal disorders until a global eradication was initiated in the twentieth century. The last cases were reported in Somalia 1977 and as a laboratory infection in the UK 1978; in 1980, the World Health Organization (WHO) declared smallpox for extinct. The smallpox virus with its very high transmissibility and mortality is still a major biothreat, because the vaccination against smallpox was stopped globally in the 1980s. For this reason, new antivirals (cidofovir, brincidofovir, and tecovirimat) and new vaccines (ACAM2000, LC16m8 and Modified Vaccine Ankara MVA) were developed. For passive immunization, vaccinia immune globulin intravenous (VIGIV) is available. Due to the relationships between orthopox viruses such as vaccinia, variola, mpox (monkeypox), cowpox, and horsepox, the vaccines (LC16m8 and MVA) and antivirals (brincidofovir and tecovirimat) could also be used in the mpox outbreak with positive preliminary data. As mutations can result in drug resistance against cidofovir or tecovirimat, there is need for further research. Further antivirals (NIOCH-14 and ST-357) and vaccines (VACΔ6 and TNX-801) are being developed in Russia and the USA. In conclusion, further research for treatment and prevention of orthopox infections is needed and is already in progress. After a brief introduction, this chapter presents the smallpox and mpox disease and thereafter full overviews on antiviral treatment and vaccination including the passive immunization with vaccinia immunoglobulins.

Structural basis of human mpox viral DNA replication inhibition by brincidofovir and cidofovir.

Mpox virus has wildly spread over 108 non-endemic regions in the world since May 2022. DNA replication of mpox is performed by DNA polymerase machinery F8-A22-E4, which is known as a great drug target. Brincidofovir and cidofovir are reported to have broad-spectrum antiviral activity against poxviruses, including mpox virus in animal models. However, the molecular mechanism is not understood. Here we report cryogenic electron microscopy structures of mpox viral F8-A22-E4 in complex with a DNA duplex, or dCTP and the DNA duplex, or cidofovir diphosphate and the DNA duplex at resolution of 3.22, 2.98 and 2.79 Å, respectively. Our structural work and DNA replication inhibition assays reveal that cidofovir diphosphate is located at the dCTP binding position with a different conformation to compete with dCTP to incorporate into the DNA and inhibit DNA synthesis. Conformation of both F8-A22-E4 and DNA is changed from the pre-dNTP binding state to DNA synthesizing state after dCTP or cidofovir diphosphate is bound, suggesting a coupling mechanism. This work provides the structural basis of DNA synthesis inhibition by brincidofovir and cidofovir, providing a rational strategy for new therapeutical development for mpox virus and other pox viruses.

The successful treatment of mpox with brincidofovir in renal transplant recipients-a report of 2 cases.

An mpox outbreak was declared in July 2022 by the world health organization (WHO). It causes a mild self-limiting disease however; in immunosuppressed hosts, it tends to cause severe disseminated infection. Most cases of mpox in sold organ transplant (SOT) recipients reported in the literature were treated with tecovirimat. Here we report two cases of severe disseminated mpox infection in renal transplant recipients that were successfully treated with brincidofovir. Both patients were discharged from the hospital with no immediate significant side effects from brincidofovir reported until the submission of this report.

Brincidofovir Effectively Inhibits Proliferation of Pseudorabies Virus by Disrupting Viral Replication.

Pseudorabies is an acute and febrile infectious disease caused by pseudorabies virus (PRV), a member of the family Herpesviridae. Currently, PRV is predominantly endemoepidemic and has caused significant economic losses among domestic pigs. Other animals have been proven to be susceptible to PRV, with a mortality rate of 100%. In addition, 30 human cases of PRV infection have been reported in China since 2017, and all patients have shown severe neurological symptoms and eventually died or developed various neurological sequelae. In these cases, broad-spectrum anti-herpesvirus drugs and integrated treatments were mostly applied. However, the inhibitory effect of the commonly used anti-herpesvirus drugs (e.g., acyclovir, etc.) against PRV were evaluated and found to be limited in this study. It is therefore urgent and important to develop drugs that are clinically effective against PRV infection. Here, we constructed a high-throughput method for screening antiviral drugs based on fluorescence-tagged PRV strains and multi-modal microplate readers that detect fluorescence intensity to account for virus proliferation. A total of 2104 small molecule drugs approved by the U.S. Food and Drug Administration (FDA) were studied and validated by applying this screening model, and 104 drugs providing more than 75% inhibition of fluorescence intensity were selected. Furthermore, 10 drugs that could significantly inhibit PRV proliferation in vitro were strictly identified based on their cytopathic effects, virus titer, and viral gene expression, etc. Based on the determined 50% cytotoxic concentration (CC50) and 50% inhibitory concentration (IC50), the selectivity index (SI) was calculated to be 26.3-3937.2 for these 10 drugs, indicating excellent drugability. The antiviral effects of the 10 drugs were then assessed in a mouse model. It was found that 10 mg/kg brincidofovir administered continuously for 5 days provided 100% protection in mice challenged with lethal doses of the human-origin PRV strain hSD-1/2019. Brincidofovir significantly attenuated symptoms and pathological changes in infected mice. Additionally, time-of-addition experiments confirmed that brincidofovir inhibited the proliferation of PRV mainly by interfering with the viral replication stage. Therefore, this study confirms that brincidofovir can significantly inhibit PRV both in vitro and in vivo and is expected to be an effective drug candidate for the clinical treatment of PRV infections.

Brincidofovir for disease progression due to suspected tecovirimat resistance in association with advanced HIV.

A man with advanced HIV presented with verrucous plaques 2-3 months after initial mpox infection. He received two courses of tecovirimat without resolution of initial mpox lesions and development of new lesions raising concern for resistance. He was treated with two doses of brincidofovir and demonstrated improvement 6 months later.

Utility of Cytochrome P450 4F2 Genotyping to Assess Drug Interaction Risk for Brincidovovir, a Cytochrome P450 4F2 Substrate.

Smallpox was eradicated in 1980 but remains a biothreat due to the potential release of variola virus into the general population. Brincidofovir, the second medicine approved by the US Food and Drug Administration to treat smallpox, is metabolized by oxidative and hydrolytic pathways. The oxidative pathway is initiated by cytochrome P450 4F2 (CYP4F2), an enzyme lacking clinical probes for drug interaction studies. The aim of this work was to assess the impact of reduced activity CYP4F2 variants (rs2108622, C/T and T/T) on brincidofovir pharmacokinetics as a surrogate for drug inhibition. Genotyping was performed on blood from healthy participants receiving oral (n = 261) and intravenous (IV, n = 49) brincidofovir across 6 phase 1 trials. Plasma concentrations were measured by validated liquid chromatography tandem mass spectrometry methods. After oral administration, subjects with the lowest activity CYP4F2 genotype (T/T) had up to 36% higher AUCinf and 29% higher Cmax while subjects with the moderate activity CYP4F2 genotype (C/T) had similar Cmax and AUCinf compared to those with the wild-type genotype. Little to no increase in brincidofovir exposure parameters was observed following IV administration. Based on the lack of significant increases in brincidofovir plasma concentrations in subjects with low activity CYP4F2, a clinically meaningful drug-drug interaction is not expected with CYP4F2 inhibitor and brincidofovir coadministration.

Clinical considerations on monkeypox antiviral medications: An overview.

Monkeypox (mpox), a virus belonging to the orthopoxvirus family, can cause a zoonotic infectious disease with morbidity and cosmetic complications. Therefore, effective antiviral drugs with appropriate safety profiles are important for the treatment of patients with mpox. To date, there is no FDA-approved drug for the treatment of mpox. However, tecovirimat, brincidofovir, and cidofovir are the candidate therapies for the management of mpox. Given the safety concerns following the use of these medications, we aimed to review evidence on the clinical considerations of mpox antiviral medications that will be useful to guide clinicians in the treatment approach. Based on the current evidence, tecovirimat has favorable clinical efficacy, safety, and side effect profile and it can be considered as first-line treatment for mpox.

AI-assisted structural consensus-proteome prediction of human monkeypox viruses isolated within a year after the 2022 multi-country outbreak.

IMPORTANCE: The 2022 outbreak of the monkeypox virus already involves, by April 2023, 110 countries with 86,956 confirmed cases and 119 deaths. Understanding an emerging disease on a molecular level is essential to study infection processes and eventually guide drug discovery at an early stage. To support this, we provide the so far most comprehensive structural proteome of the monkeypox virus, which includes 210 structural models, each computed with three state-of-the-art structure prediction methods. Instead of building on a single-genome sequence, we generated our models from a consensus of 3,713 high-quality genome sequences sampled from patients within 1 year of the outbreak. Therefore, we present an average structural proteome of the currently isolated viruses, including mutational analyses with a special focus on drug-binding sites. Continuing dynamic mutation monitoring within the structural proteome presented here is essential to timely predict possible physiological changes in the evolving virus.

Adenovirus infection in allogeneic hematopoietic cell transplantation.

Adenovirus (AdV) infection occurs in 0-20% of patients in the first 3-4 months after allogeneic hematopoietic cell transplantation (HCT), being higher in pediatric than in adult patients. About 50% of AdV infections involve the blood, which in turn, correlates with an increased risk developing AdV diseases, end-organ damage, and 6-month overall mortality. The main risk factors for AdV infection are T-cell depletion of the graft by ex vivo selection procedures or in vivo use of alemtuzumab or antithymocyte serum, development of graft versus host disease (GVHD) grade III-IV, donor type (haploidentical or human leucocyte antigen mismatched related donor > cord blood> unrelated matched donor) and severe lymphopenia (<0.2 × 109 /L). The prevention of AdV disease relies on early diagnosis of increasing viral replication in blood or stool and the pre-emptive start of cidofovir as viral load exceeds the threshold of ≥102-3 copies/mL in blood and/or 106 copies/g stool in the stool. Cidofovir (CDV), a cytosine monophosphate nucleotide analog, is currently the only antiviral recommended for AdV infection despite limited efficacy and moderate risk of nephrotoxicity. Brincidofovir, a lipid derivative of CDV with more favorable pharmacokinetics properties and superior efficacy, is not available and currently is being investigated for other viral infections. The enhancement of virus-specific T-cell immunity in the first few months post-HCT by the administration of donor-derived or third-party-donor-derived virus-specific T-cells represents an innovative and promising modality of intervention and data of efficacy and safety of the ongoing prospective randomized studies are eagerly awaited.

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.

Emerging pharmacological strategies for treating and preventing mpox.

INTRODUCTION: Since May 2022, there have been nearly 87,000 documented cases of mpox worldwide, with 119 deaths. Pharmacological interventions for mpox include the MVA-BN smallpox vaccine, tecovirimat, cidofovir, its pro-drug brincidofovir, and vaccinia immune globulin intravenous (VIGIV). AREAS COVERED: The literature search and information gathering for this review included the PubMed database focusing on mpox and monkeypox, in combination with tecovirimat, brincidofovir, cidofovir, VIGIV, and smallpox vaccine. WHO.int, CDC.gov, FDA.gov, and ClinicalTrials.gov websites were accessed for the most recent information on the mpox outbreak. Mechanisms for deployment and access to treatment including expanded access, emergency use, and clinical trials will be discussed. Treatment outcomes with safety data will be presented. EXPERT OPINION: The vaccine as a preventive measure, along with numerous treatment options, largely controlled the outbreak, although deployment of each could be improved upon to hasten and broaden access. More widespread coverage by the vaccine is necessary to prevent future resurgence of mpox. Tecovirimat has emerged as a safe frontline treatment for mpox, while brincidofovir use has been limited by safety concerns. VIGIV and cidofovir should be reserved for the most severe cases in which other options are not fully effective.

Challenges in the treatment and prevention of monkeypox infection; A comprehensive review.

Human monkeypox (HMPX) is a zoonotic disease, literally meaning that it can be passed on from animals (non-primate) to human (primate). All the reported and recorded cases have been traced back either to international travel or import of African animals. In the Unites states, sporadic monkeypox cases have been reported in specific over the past 50 years, starting its first identification in the Democratic Republic of the Congo (D.R.C.) in 1970. Due to its extreme versatility, this disease poses threat as a serious public health issue that needs to be monitored, researched and prevented. Data indicate that prior immunization with the smallpox vaccine is beneficial and may provide protection against the monkeypox virus. JYNNEOSTM is a live viral vaccine that has been approved to improve clinical manifestations of the infection. On the other hand, public ignorance about safety precaution towards monkeypox post-COVID is another challenge that needs to be overcome in tackling HMPX as a possible re-emergent infection. This review is a collation of the epidemiology, etiology, transmission, clinical features and treatment of human monkeypox (HMPX).

Antivirals for the treatment of Monkeypox: utilization in the general and HIV-positive population and gaps for research. A short narrative review.

Monkeypox (Mpox) is an emerging viral disease caused by the monkeypox virus (MPXV), a double-stranded DNA virus member of the genus Orthopoxvirus, first reported in humans in 1970. Since May 2022, a global spread of the infection has occurred that the World Health Organization (WHO) declared a public health emergency. In view of the global threat, efforts have been devoted to bolstering the disease spread as well as identifying viable therapeutic modalities. People living with HIV may be at an increased risk of adverse outcomes and may require antiviral treatment. With regard to antiretroviral drugs agents, the anticipated adverse drug reactions do not preclude the co-administration of combined antiretroviral therapy and antivirals for mpox. More data on treatment recommendations and efficacy in patients with immunodeficiency due to HIV is needed. In this review, tecovirimat, cidofovir and brincidofovir - antiviral agents with activity against MPXV and other Orthopoxviruses are reviewed, their utilization in vulnerable patient groups affected by mpox such as people living with HIV and possible gaps for future research. Tecovirimat is an inhibitor of the Orthopoxvirus VP37 envelope wrapping protein thus rendering enveloped virus formation impossible. Cidofovir and its prodrug brincidofovir interfere with DNA synthesis through DNA polymerase inhibition. Ongoing research is intensified to verify efficacy and applicability.

Brincidofovir is a robust replication inhibitor against African swine fever virus in vivo and in vitro.

African swine fever virus (ASFV) infection is a major public and socioeconomic concern that has a serious impact on the global swine industry. Unfortunately, there are currently no commercially available vaccines or antiviral agents that are both safe and effective against ASFV. In the study, we use primary porcine alveolar macrophages to screen a kinase inhibitor library for anti-ASFV compounds. Six candidate compounds that inhibited ASFV infection with inhibition of > 90% were identified, among which brincidofovir exhibited optimal inhibitory effects on ASFV. Brincidofovir reduces ASFV replication in a dose-dependent manner (IC50 = 2.76 nM) without cytotoxicity (CC50 = 58 µM). It possesses the ability to reduce viral titres and inhibit viral structural protein expression. Time-of-addition assays suggest that the compound interferes with the post-invasion stage of the viral infection cycle. In pig challenge experiments, brincidofovir was indicated to protect pigs against ASFV-induced lethality by decreasing the viral load in organs and peripheral blood, while it alleviated the histopathological changes associated with ASFV infection. Furthermore, brincidofovir also decreased viral shedding in pigs with ASFV infection. Our data together demonstrate that brincidofovir may serve as a potentially effective agent for the prevention and control of ASFV infection, whereas further investigations are still required.

Machine learning and classical MD simulation to identify inhibitors against the P37 envelope protein of monkeypox virus.

Monkeypox virus (MPXV) outbreak is a serious public health concern that requires international attention. P37 of MPXV plays a pivotal role in DNA replication and acts as one of the promising targets for antiviral drug design. In this study, we intent to screen potential analogs of existing FDA approved drugs of MPXV against P37 using state-of-the-art machine learning and computational biophysical techniques. AlphaFold2 guided all-atoms molecular dynamics simulations optimized P37 structure is used for molecular docking and binding free energy calculations. Similar to members of Phospholipase-D family , the predicted P37 structure also adopts a ß-α-ß-α-ß sandwich fold, harbouring strongly conserved HxKxxxxD motif. The binding pocket comprises of Tyr48, Lys86, His115, Lys117, Ser130, Asn132, Trp280, Asn240, His325, Lys327 and Tyr346 forming strong hydrogen bonds and dense hydrophobic contacts with the screened analogs and is surrounded by positively charged patches. Loops connecting the two domains and C-terminal region exhibit high degree of flexibility. In some structural ensembles, the partial disorderness in the C-terminal region is presumed to be due to its low confidence score, acquired during structure prediction. Transition from loop to ß-strands (244-254 aa) in P37-Cidofovir and its analog complexes advocates the need for further investigations. MD simulations support the accuracy of the molecular docking results, indicating the potential of analogs as potent binders of P37. Taken together, our results provide preferable understanding of molecular recognition and dynamics of ligand-bound states of P37, offering opportunities for development of new antivirals against MPXV. However, the need of in vitro and in vivo assays for confirmation of these results still persists.Communicated by Ramaswamy H. Sarma.

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

The monkeypox disease (MPX) outbreak of 2022 has been reported in more than one hundred countries and is becoming a global concern. Unfortunately, only a few treatments, such as tecovirimat (TCV), are available against MPX. Brincidofovir (BCV) is a United States Food and Drug Administration (USFDA)-approved antiviral against smallpox. This article reviews the potential of BCV for treating MPX and other Orthopoxvirus (OPXVs) diseases. The literature for this review was collected from PubMed, authentic websites (USFDA, Chimerix), and freely available patent databases (USPTO, Espacenet, and Patentscope). BCV (a lipophilic derivative of cidofovir) has been discovered and developed by Chimerix Incorporation, USA. Besides smallpox, BCV has also been tested clinically for various viral infections (adenovirus, cytomegalovirus, ebola virus, herpes simplex virus, and double-stranded DNA virus). Many health agencies and reports have recommended using BCV for MPX. However, no health agency has yet approved BCV for MPX. Accordingly, the off-label use of BCV is anticipated for MPX and various viral diseases. The patent literature revealed some important antiviral compositions of BCV. The authors believe there is a huge opportunity to create novel, inventive, and patentable BCV-based antiviral therapies (new combinations with existing antivirals) for OPXVs illnesses (MPX, smallpox, cowpox, camelpox, and vaccinia). It is also advised to conduct drug interaction (food, drug, and disease interaction) and drug resistance investigations on BCV while developing its combinations with other medications. The BCV-based drug repurposing options are also open for further exploration. BCV offers a promising opportunity for biosecurity against OPXV-based bioterrorism attacks and to control the MPX outbreak of 2022.

Monkeypox and drug repurposing: seven potential antivirals to combat the viral disease.

The growing concern about the monkeypox (Mpox) virus infection has garnered a lot of public attention. However, the treatment options available to combat the same is limited to tecovirimat. Additionally, in a possible incidence of resistance, hypersensitivity, or adverse drug reaction, it is imperative to devise and reinforce the second-line therapy. Thus, in this editorial, the authors suggest seven antiviral drugs that could potentially be repurposed to combat the viral illness.

Brincidofovir: A Novel Agent for the Treatment of Smallpox.

OBJECTIVE: This article reviews the published data encompassing the development, pharmacology, efficacy, and safety of brincidofovir, a nucleotide analogue DNA polymerase inhibitor developed for the treatment of smallpox. DATA SOURCES: A literature review was conducted in PubMed, MEDLINE, and Clinicaltrials.gov from inception up to December 2022, using terms Tembexa, brincidofovir, CMX001, smallpox treatment, and variola treatment. STUDY SELECTION AND DATA EXTRACTION: Data were limited to studies published in English language, which evaluated the efficacy and safety of brincidofovir. DATA SYNTHESIS: Two surrogate animal models were included in the Food and Drug Administration's (FDA) decision to approve brincidofovir: ectromelia virus in mice and rabbitpox in rabbits. Phases 2 and 3 studies established safety for approval. Brincidofovir biweekly for the treatment of disseminated adenovirus disease resulted in all-cause mortality, ranging from 13.8% to 29%. In a study for cytomegalovirus prophylaxis, patients with clinically significant cytomegalovirus infection through week 24 posttransplant was 51.2% with brincidofovir and 52.3% with placebo. CONCLUSIONS: Brincidofovir adds a second oral agent to treat smallpox, with a different mechanism of action than tecovirimat. In the event of a smallpox outbreak, prompt treatment will be necessary to contain its spread. Brincidofovir shows efficacy in surrogate animal models. In healthy volunteers and individuals treated, or used as prophylaxis, for cytomegalovirus or adenovirus, the primary adverse events were gastrointestinal in addition to transient hepatotoxicity. Additionally, excessive deaths were observed in hematopoietic cell transplant patients receiving it as cytomegalovirus prophylaxis, requiring a black box warning.