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.

Antivirals With Activity Against Mpox: A Clinically Oriented Review.

Mpox virus is an emergent human pathogen. While it is less lethal than smallpox, it can still cause significant morbidity and mortality. In this review, we explore 3 antiviral agents with activity against mpox and other orthopoxviruses: cidofovir, brincidofovir, and tecovirimat. Cidofovir, and its prodrug brincidofovir, are inhibitors of DNA replication with a broad spectrum of activity against multiple families of double-stranded DNA viruses. Tecovirimat has more specific activity against orthopoxviruses and inhibits the formation of the extracellular enveloped virus necessary for cell-to-cell transmission. For each agent, we review basic pharmacology, data from animal models, and reported experience in human patients.

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.

Progression of human monkeypox infection despite tecovirimat in an immunocompromised adult.

We report a case of an immunocompromised man with monkeypox who experienced disease progression despite timely initiation of tecovirimat and ultimately required utilization of cidofovir and VIGIV for treatment. In immunocompromised patients, monkeypox might present with a more severe course of disease requiring consideration of alternative treatment strategies.

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.

Human monkeypox: a comparison of the characteristics of the new epidemic to the endemic disease.

In May 2022, a new global outbreak of mpox (formerly, human monkeypox) emerged that was declared a public health emergency of international concern by the World Health Organization on July 23, 2022. With new patterns of person-to-person spread within sexual networks in nonendemic countries and several differences from the classic disease course, we performed a comprehensive review of existing literature on human monkeypox to discuss epidemiology, modes of transmission, clinical presentation and asymptomatic infection, diagnostics, therapeutics, and vaccines with the primary aim to identify important areas for future research of this new epidemic form of the disease. A comprehensive literature search was performed of all published literature to August 15, 2022. Historically, in regions of monkeypox virus endemicity, human outbreaks have occurred related to discrete zoonotic events. The animal reservoir is unknown, but the virus has been isolated from rodents. Traditionally, transmission occurred by direct or indirect contact with an infected animal. In nonendemic countries affected in the 2022 outbreak, almost exclusive person-to-person spread has been observed, and most cases are connected to sexual networks of gay, bisexual, and other men who have sex with men. After an incubation period of approximately 13 days, in traditional human cases affected persons developed a febrile prodrome preceding a rash that started on the face and body, spread centrifugally to the palms and soles and healed monomorphically over two to four weeks. However, in the 2022 outbreak, the febrile illness is often absent or occurs after the onset of the rash. The rash presents primarily in the anogenital region and face before disseminating throughout the body, with lesions displaying regional pleomorphism. There is a paucity of data for the role of antiviral agents or vaccines. The epidemiology and clinical course of mpox has changed in the 2022 epidemic from that observed with the endemic disease. There is an urgent need to establish rapid and collaborative research platforms to diagnose, treat and prevent disease and inform important public health and other strategies to stop the spread of disease.

Risks and outcomes of adenovirus disease in pediatric hematopoietic stem cell transplant recipients-Comparison of current antiviral treatment options.

BACKGROUND: Adenovirus disease (ADVd) is a significant burden in pediatric hematopoietic stem cell transplant (HSCT) recipients. However, current knowledge of risk factors associated with poor clinical outcome and the effectiveness of antiviral therapy are not well understood. This study determined the relationship between transplant characteristics and risk of ADVd and also compared time to resolution of disease between pediatric patients who did and did not receive antiviral therapy. METHODS: We conducted a retrospective, single-center cohort study of pediatric patients undergoing HSCT at Duke University (2005-2016). Cases of ADVd were defined a priori using a classification tool. Cox proportional hazards (CPH) regression models were used to compare the hazard of ADVd between HSCT recipients differing by type of transplant and type of conditioning regimen. The hazard of time to resolution of ADVd by antiviral therapy (cidofovir, brincidofovir, both, or neither) was compared. RESULTS: Ninety-three of 830 subjects had ADVd post-HSCT (11.2%). Umbilical cord transplant (UCT) recipients had 2.30 (95% CI 1.57, 6.90, P = .002) higher hazard of developing ADVd compared to non-cord allogeneic transplants, and 6.30 higher (95% CI 2.70, 19.61, P < .001) hazard compared to autologous transplants. Subjects who did not receive antiviral therapy experienced earlier resolution of ADVd compared to subjects who received therapy, even after adjusting for subjects with disseminated disease (HR [95% CI]: 3.75 [1.57, 8.93], P = .003). CONCLUSIONS: Pediatric UCT recipients are at a higher risk for ADVd. Antiviral therapy was not associated with an earlier resolution of ADVd, even in patients with higher disease burden.

A eulogy for Dr Francisco Miguel Marty Forero.

As some of those who were lucky enough to have been mentored by Dr Francisco Marty in transplant infectious diseases, we stand with the larger medical community in mourning his untimely death and in commemorating him as a uniquely exceptional and talented physician, investigator, teacher, mentor, friend, artist, and human being.

[Which drugs to treat Adenovirus infections?] / Quelles molécules pour traiter des infections à Adénovirus ?

Human adenoviruses (HAdV) infections are generally mild and resolve spontaneously in immunocompetent individuals. However, HAdV infections can have a major clinical impact in immunocompromised patients. HAdV infections are associated with high morbidity and mortality in recipients of allogeneic stem cell transplants, particularly children. There are currently no drug approved for the treatment of HAdV infections. Nevertheless, some nucleotide analogues are used under temporary authorization for use, such as cidofovir or brincidofovir. Cidofovir inhibits the replication of HAdV but its nephrotoxicity and its low tissue concentrations severely limit its use. Brincidofovir, a cidofovir prodrug, with a better bioavailability and no nephrotoxicity was evaluated in the treatment of HAdV infections, but its development was recently stopped and it is currently no longer available in ATU. Other molecules with anti-HAdV activity are still in early stages of development. Adoptive immunotherapy by adenovirus-specific T-cell transfer is an interesting option but should be anticipated in patients with high risks of disseminated infections. Given the small therapeutic panel available, it is critical to continue the search for new anti-HAdV molecules, which remains mainly conducted by academic laboratories.

Will There Be a Cure for Ebola?

Despite the unprecedented Ebola virus outbreak response in West Africa, no Ebola medical countermeasures have been approved by the US Food and Drug Administration. However, multiple valuable lessons have been learned about the conduct of clinical research in a resource-poor, high risk-pathogen setting. Numerous therapeutics were explored or developed during the outbreak, including repurposed drugs, nucleoside and nucleotide analogues (BCX4430, brincidofovir, favipiravir, and GS-5734), nucleic acid-based drugs (TKM-Ebola and AVI-7537), and immunotherapeutics (convalescent plasma and ZMapp). We review Ebola therapeutics progress in the aftermath of the West Africa Ebola virus outbreak and attempt to offer a glimpse of a path forward.

Brincidofovir for the treatment of human adenovirus infection in pediatric solid organ transplant recipients: A case series.

HAdV viremia can cause significant morbidity among pediatric recipients of SOT with variability in incidence and severity of disease based on the type of allograft. Currently, there are no US FDA-approved treatments for HAdV infections, and historically, the mainstay of treatment has been decreasing immunosuppression, with antiviral therapies reserved for those with severe disease. We describe the treatment of four pediatric SOT recipients (two kidney, one combined kidney-liver, and one liver) presenting with HAdV disease at our institution using brincidofovir. Our case series highlights the variability in presentation and the potential for severe disease in pediatric SOT recipients as we review disease presentation, disease course, complications, and treatment with brincidofovir.

A Randomized, Double-Blind, Placebo-Controlled Phase 3 Trial of Oral Brincidofovir for Cytomegalovirus Prophylaxis in Allogeneic Hematopoietic Cell Transplantation.

Cytomegalovirus (CMV) infection is a common complication of allogeneic hematopoietic cell transplantation (HCT). In this trial, we randomized adult CMV-seropositive HCT recipients without CMV viremia at screening 2:1 to receive brincidofovir or placebo until week 14 post-HCT. Randomization was stratified by center and risk of CMV infection. Patients were assessed weekly through week 15 and every third week thereafter through week 24 post-HCT. Patients who developed clinically significant CMV infection (CS-CMVi; CMV viremia requiring preemptive therapy or CMV disease) discontinued the study drug and began anti-CMV treatment. The primary endpoint was the proportion of patients with CS-CMVi through week 24 post-HCT; patients who discontinued the trial or with missing data were imputed as primary endpoint events. Between August 2013 and June 2015, 452 patients were randomized at a median of 15 days after HCT and received study drug. The proportion of patients who developed CS-CMVi or were imputed as having a primary endpoint event through week 24 was similar between brincidofovir-treated patients and placebo recipients (155 of 303 [51.2%] versus 78 of 149 [52.3%]; odds ratio, .95 [95% confidence interval, .64 to 1.41]; P = .805); fewer brincidofovir recipients developed CMV viremia through week 14 compared with placebo recipients (41.6%; P < .001). Serious adverse events were more frequent among brincidofovir recipients (57.1% versus 37.6%), driven by acute graft-versus-host disease (32.3% versus 6.0%) and diarrhea (6.9% versus 2.7%). Week 24 all-cause mortality was 15.5% among brincidofovir recipients and 10.1% among placebo recipients. Brincidofovir did not reduce CS-CMVi by week 24 post-HCT and was associated with gastrointestinal toxicity.

Efficacy of brincidofovir as prophylaxis against HSV and VZV in hematopoietic cell transplant recipients.

Allogeneic hematopoietic cell transplant (HCT) recipients are at risk for herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. Routine prophylaxis with acyclovir is recommended during periods of immunosuppression. Brincidofovir (BCV, CMX001), a lipid conjugate of cidofovir, has shown in vitro activity against HSV/VZV, but has not been formally studied for HSV/VZV prophylaxis. We report our clinical experience of BCV for HSV/VZV prophylaxis in HCT recipients. This was a retrospective review of 30 hematopoietic cell transplant (HCT) recipients between 8/2010 and 8/2015 who received BCV doses not exceeding 200 mg/week for adults/adolescents and 4 mg/kg/week for pediatric (<12 years) patients, for ≥14 days BCV without concomitant acyclovir under clinical trials or single patient use. HSV/VZV cases during BCV treatment were confirmed by viral culture or PCR and clinical symptoms. Of 30 patients who met the inclusion criteria, 27 (90%) patients were adults and 22 (73%) patients received T-cell depleted HCT. The most common indications for BCV were cytomegalovirus in 12 patients (40%) and adenovirus in 11 patients (37%). One patient was treated for acyclovir-resistant HSV and one for disseminated VZV. There were two breakthrough cases of HSV infection during 2170 patient-days. There were no cases of breakthrough VZV infection. The overall rate of breakthrough HSV infection was 1.0 per 1000 patient-days, without any breakthrough VZV infections. Our study provides the only available-albeit limited-evidence on the potential efficacy of BCV for HSV/VZV prophylaxis in HCT patients. Additional studies are needed to further assess the efficacy and safety of BCV in the setting.

Brincidofovir for Asymptomatic Adenovirus Viremia in Pediatric and Adult Allogeneic Hematopoietic Cell Transplant Recipients: A Randomized Placebo-Controlled Phase II Trial.

Adenovirus infection in immunocompromised patients contributes to significant morbidity and mortality, especially after allogeneic hematopoietic cell transplantation (HCT). Brincidofovir (BCV, CMX001) is an orally bioavailable lipid conjugate of cidofovir that has in vitro activity against adenoviruses and other double-stranded DNA viruses. This randomized placebo-controlled phase II trial evaluated pre-emptive treatment with BCV for the prevention of adenovirus disease in pediatric and adult allogeneic HCT recipients with asymptomatic adenovirus viremia. Allogeneic HCT recipients with adenovirus viremia were randomized 1:1:1 to receive oral BCV 100 mg (2 mg/kg if <50 kg) twice weekly (BIW), BCV 200 mg (4 mg/kg if <50 kg) once weekly (QW), or placebo for 6 to 12 weeks, followed by 4 weeks of post-treatment follow-up. For randomization, subjects were stratified by screening absolute lymphocyte count (<300 cells/mm3 versus ≥300 cells/mm3). Assignment to BCV or placebo was double blinded; dose frequency was unblinded. The primary endpoint was the proportion of subjects experiencing treatment failure, defined as either progression to probable or definitive adenovirus disease or confirmed increasing adenovirus viremia (≥1 log10 copies/mL) during randomized therapy. Between June 2011 and December 2012, 48 subjects were randomized to the BCV BIW (n = 14), BCV QW (n = 16), or placebo (n = 18) groups. The proportion of subjects with treatment failure in the BCV BIW group was 21% (odds ratio, .53; 95% confidence interval [CI], .11 to 2.71; P = .45), 38% (odds ratio, 1.23; 95% CI, .30 to 5.05, P = .779) in the BCV QW group, and 33% in the placebo group. All-cause mortality was lower in the BCV BIW (14%) and BCV QW groups (31%) relative to the placebo group (39%), but these differences were not statistically significant. After 1 week of therapy, 8 of 12 subjects (67%) randomized to BCV BIW had undetectable adenovirus viremia (<100 copies/mL), compared with 4 of 14 subjects (29%) randomized to BCV QW and 5 of 15 subjects (33%) randomized to placebo. In a post hoc analysis of subjects with viremia ≥1000 copies/mL at baseline, 6 of 7 BCV BIW subjects (86%) achieved undetectable viremia compared with 2 of 8 placebo subjects (25%; P = .04). Early treatment discontinuation because of adverse events was more common in subjects treated with BCV than with placebo. Diarrhea was the most common event in all groups (57% BCV BIW, 38% BCV QW, 28% placebo), but it led to treatment discontinuation in only 1 subject receiving BCV QW. Events diagnosed as acute graft-versus-host disease, primarily of the gastrointestinal tract, were more frequent in the BCV BIW group (50%) than in the BCV QW (25%) and placebo (17%) groups. There was no evidence of myelotoxicity or nephrotoxicity in BCV-treated subjects. The results of this trial confirm the antiviral activity of BCV against adenoviruses. Further investigation is ongoing to define the optimal treatment strategy for HCT recipients with serious adenovirus infection and disease.

Analysis of Mutations in the Gene Encoding Cytomegalovirus DNA Polymerase in a Phase 2 Clinical Trial of Brincidofovir Prophylaxis.

Brincidofovir is an oral antiviral in development for prevention of cytomegalovirus disease. Cytomegalovirus genotyping results from a phase 2 trial comparing brincidofovir to placebo for prophylaxis against cytomegalovirus infection in hematopoietic cell transplant recipients provided initial data on the clinical resistance profile for brincidofovir. In this study, no known resistance-associated mutations were detected in brincidofovir-treated subjects; identified genotypic substitutions did not confer resistance to cytomegalovirus antivirals in vitro, suggesting that these changes represent polymorphisms unrelated to brincidofovir resistance. Lack of evidence for genotypic resistance during prophylaxis suggests that first-line use of brincidofovir for prevention of cytomegalovirus infection may preserve downstream options for patients.

Brincidofovir treatment of acyclovir-resistant disseminated varicella zoster virus infection in an immunocompromised host.

Brincidofovir (BCV) is a broad-spectrum antiviral agent active in vitro against double-stranded DNA viruses including herpesviruses, adenoviruses, polyomaviruses, and poxviruses. We report successful BCV use in management of disseminated acyclovir- and cidofovir-resistant varicella zoster virus in an immunocompromised hematopoietic stem cell transplant patient with chronic graft-versus-host disease who was intolerant to foscarnet.

Brincidofovir clearance of acyclovir-resistant herpes simplex virus-1 and adenovirus infection after stem cell transplantation.

Infections with adenovirus (AdV) and herpesviruses can result in considerable morbidity and mortality in pediatric hematopoietic stem cell transplant (SCT) recipients. Herpes simplex virus (HSV) reactivations are usually prevented by acyclovir (ACV) prophylaxis, whereas cidofovir (CDV) has been used off indication to manage AdV infections. We report a child with myelodysplastic syndrome undergoing multiple SCT, who experienced HSV-1 disease including severe mucositis and herpetic whitlow, as well as high viral load AdV DNAemia. Both ACV and CDV were ineffective; however, viral loads were decreased with brincidofovir, resulting in viral clearance. A subsequent Epstein-Barr virus disease with relevant meningoencephalitis responded to rituximab.

Brincidofovir for polyomavirus-associated nephropathy after allogeneic hematopoietic stem cell transplantation.

Polyomavirus-associated nephropathy (PVAN) is common in patients who have undergone kidney transplantation and has been reported in hematopoietic stem cell (HSC) transplant recipients. Aside from reduction of immunosuppression, few therapeutic options exist for treatment of PVAN. We report a case of PVAN in a severely immunocompromised allogeneic HSC transplant recipient that was treated with brincidofovir without reduction of immunosuppression. We review our institutional experience of PVAN in HSC transplantation and discuss the potential use of brincidofovir for treatment.

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.