Clinical uses of cidofovir

How I treat adenovirus in hematopoietic stem cell transplant recipients

Adenovirus (AdV) infections are very common in the general pediatric population. The delayed clearance in young persons imposes a threat to immunocompromised patients after hematopoietic stem cell transplantation (HSCT), who can reactivate the virus, resulting in life-threatening disseminated disease. Although a definitive cure requires adequate immune reconstitution, 2 approaches appear to be feasible and effective to improve the outcomes of AdV infections. Strict monitoring with AdV quantitative polymerase chain reaction followed by preemptive treatment with low-dose (1 mg/kg) cidofovir 3 times a week, is effective in most cases to bridge the severely immunocompromised period shortly after HSCT, with acceptable toxicity rates. For centers who have the access, AdV-specific cytotoxic T cells can be the other important cornerstone of anti-AdV therapy with promising results so far. Methods to positively influence the reconstitution of the immune system after HSCT and optimizing new and currently available cellular immunotherapies will make HSCT safer against the threat of AdV infection/reactivation and associated disease.

Local and systemic effects of intralaryngeal injection of cidofovir in a canine model

OBJECTIVE

The safety of intralaryngeal injection of cidofovir remains a concern. Our goal was to evaluate local and systemic effects of intralaryngeal injection of cidofovir.

STUDY DESIGN

Animal study using a canine model.

METHODS

Two groups of three young beagle dogs (6 vocal folds in each group) were used. Subepithelial vocal fold injections were performed in each group biweekly for 6 months with 0, 2.5, 5, 10, 20, and 37.5 mg cidofovir in a 0.5 mL volume. Direct laryngoscopy was performed at each injection interval. Complete blood cell count and renal parameters were measured at baseline and monthly thereafter. Histopathologic examination of the vocal folds was performed after the 6-month injection period in one group of animals and after an additional 6-month observation period in the second group.

RESULTS

Endomysial edema with muscle fiber separation and dose-dependent atrophy and scarring of the vocal folds was present. Onset of atrophy and scarring was observed after 3, 7, and 11 injections in the vocal folds injected with 37.5, 20, and 10 mg cidofovir, respectively. After the 6-month observation period, recovery of histologic abnormalities was complete in the low-dose (0, 2.5 mg) vocal folds, near complete in the intermediate-dose (5, 10 mg) vocal folds, and no apparent recovery was seen in the high-dose (20, 37.5 mg) vocal folds. Leukocyte count and renal parameters remained unchanged at up to 4.26 mg/kg body weight of systemic dose of cidofovir.

CONCLUSIONS

Intralaryngeal cidofovir leads to dose-dependent scarification of the vocal folds that appears irreversible at higher doses. Lower concentrations of this drug should be used in intralesional intralaryngeal use.

Antiviral drug resistance: mechanisms and clinical implications

Antiviral drug resistance is an increasing concern in immunocompromised patient populations, where ongoing viral replication and prolonged drug exposure lead to the selection of resistant strains. Rapid diagnosis of resistance can be made by associating characteristic viral mutations with resistance to various drugs as determined by phenotypic assays. Management of drug resistance includes optimization of host factors and drug delivery, selection of alternative therapies based on knowledge of mechanisms of resistance, and the development of new antivirals. This article discusses drug resistance in herpesviruses and hepatitis B.

Antivirals for cytomegalovirus infection in neonates and infants: focus on pharmacokinetics, formulations, dosing, and adverse events

Cytomegalovirus (CMV) infection is very common throughout the world, and has become more of a pediatric clinical concern given the high incidence of congenital CMV infections as well as the increasing numbers of immunocompromised patients. Because of this, the need for antiviral therapies in infants and neonates is growing. Currently, there are four antivirals available that are active against CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. At this time, none have approved indications for use in children. Although there are limited data regarding the dose, pharmacokinetics (PK), safety, and adverse events for some of these antivirals, ganciclovir, and its oral prodrug valganciclovir, have been the best studied in the infant and neonate populations. In general, pharmaceutical PK studies in young children are limited by the constraints of sampling difficulties and blood volume requirements; fewer sampling times and studies may be available for drug evaluation. Given this caveat, ganciclovir and valganciclovir PK in children thus far appears to follow a monocompartmental model, contrary to what has been described in adults. However, when normalized for weight, the volume of distribution, clearance, and half-life of ganciclovir are similar to those found in adults. Given the findings that ganciclovir (and thus valganciclovir) clearance is directly proportionate to renal function, care must be taken when administering the drug to patients with impaired renal function. Recent studies evaluating valganciclovir PK in infants (at a dose of 16 mg/kg every 12 hours) have shown similar areas under the plasma concentration-time curve (AUCs) to intravenous ganciclovir (at a dose of 6 mg/kg every 12 hours), and that these AUCs remain quite stable over a number of weeks. As seen in adults, oral ganciclovir has a low bioavailability (4.8% in a pediatric analysis) and is therefore a poor alternative for treating serious CMV infections. Neutropenia is the most frequent toxicity associated with ganciclovir and valganciclovir therapy, whereas significant (and possibly irreversible) renal toxicity can be seen with cidofovir. Foscarnet administration can also result in renal toxicity as well as significant electrolyte imbalances. Several of these drugs have potential toxicities that are of concern, including carcinogenesis, teratogenesis, and azospermia (ganciclovir, valganciclovir, and cidofovir) and deposition into bone or dentition (foscarnet) that may have significant implications when treating an infant. Given these potential ill effects, careful consideration of the indications for the clinical use of these antivirals is necessary before using them for CMV infection in neonates and infants.

Sexually transmitted papillomavirus infections: epidemiology pathogenesis, clinic, morphology, important differential diagnostic aspects, current diagnostic and treatment options

The family of human papilloma viruses (HPV) comprises more than 100 genotypes. Approximately 30 of the genotypes are responsible for infections in the human anogenital area. A precisely defined algorithm with the goal of diagnosing and removing HPV for a prolonged or indefinite length of time, as well as to protect the patient from any malignant ransformation, does not currently exist. The identification of HPV strains by PCR or DNA hybridization in lesional tissue provides higher security for the patients. In high-risk patients additional colposcopy, rectoscopy, and rethroscopy/cystoscopy increase the probability of proper diagnosis and the application of a reliable therapeutic strategy. Removal of lesions by means of invasive methods, such as electrodessication, cryosurgery, and/or laser therapy, may be successful and could be combined pre- and postoperatively with the local application of podophyllotoxin, Trichloroacetic acid, 5-fluorouracil epinephrine gel, imiquimod, cidofovir or interferon. The administration of vaccine to young patients prevents to a significant extent the clinical manifestation of the most frequent viral strains, being HPV-6,-11 and -18. The different therapeutic methods must be applied in accordance with the clinical picture, taking into account the patient's general status, the presence of concomitant diseases, as well as the local and systematic compatibility of the side effects of each remedy. The review focuses on the diagnosis and treatment options of sexually transmitted HPV-infections and includes synopsis of the most recent literature regarding new data of epidemiology, pathogenesis, ifferential diagnosis and morphology of HPV infections in humans.

Mousepox in the C57BL/6 strain provides an improved model for evaluating anti-poxvirus therapies

The intranasal lethal mousepox model employing the A/Ncr mouse strain is used to evaluate anti-orthopoxvirus therapies. These infections mimic large droplet transmission and result in 100% mortality within 7-10 days with as little as 1 PFU of ectromelia virus. Unlike the A/Ncr model, humans are less susceptible to lethal respiratory infections with variola virus and monkeypox virus as demonstrated by their lower mortality rates. In this study we show that a low dose intranasal infection of C57BL/6 mice results in 60-80% mortality and better models smallpox. Comparing CMX001 (HDP-cidofovir) efficacy in the A/Ncr strain and the C57BL/6 strain revealed that delayed treatment with CMX001 is more efficacious at preventing severe disease in the C57BL/6 strain. The increased efficacy of CMX001 in C57BL/6 over A/Ncr following an intranasal infection with ectromelia appears to be mediated by a stronger Th1 cell mediated response. Following footpad infection we show that the C57BL/6 strain has earlier and more robust transcriptional activity, Th1 cytokine secretions, antigen presenting activity and IFNγ splenic CD8+ T cell responses as compared to the A/Ncr strain. As a result of the enhanced immune response in the C57BL/6 strain, non-lethal intradermal ectromelia infections can therapeutically protect up to 3 days following a homologous, lethal intranasal infection – much like how smallpox vaccination can protect humans for up to 4 days following intranasal variola infection.

Design and synthesis of vidarabine prodrugs as antiviral agents

5'-O-D- and L-amino acid derivatives and 5'-O-(D- and L-amino acid methyl ester phosphoramidate) derivatives of vidarabine (ara-A) were synthesized as vidarabine prodrugs. Some compounds were equi- or more potent in vitro than vidarabine against two pox viruses and their uptake by cultured cells was improved compared to the parent drug.

Ethacrynic and alpha-lipoic acids inhibit vaccinia virus late gene expression

Smallpox was declared eradicated in 1980. However recently, the need of agents effective against poxvirus infection has emerged again. In this paper, we report an original finding that two redox-modulating agents, the ethacrynic and α-lipoic acids (EA, LA), inhibit growth of vaccinia virus (VACV) in vitro. The effect of EA and LA was compared with those of β-mercaptoethanol, DTT and ascorbic acid, but these agents increased VACV growth in HeLa G cells. The inhibitory effects of EA and LA on the growth of VACV were further confirmed in several cell lines of different embryonic origin, in epithelial cells, fibroblasts, macrophages and T-lymphocytes.

Finally, we have analyzed the mechanism of action of the two agents. They both decreased expression of VACV late genes, as demonstrated by western blot analysis and activity of luciferase expressed under control of different VACV promoters. In contrast, they did not inhibit virus entry into the cell, expression of VACV early genes or VACV DNA synthesis.

The results suggest new directions in development of drugs effective against poxvirus infection.

Using Biomarkers to Stage Disease Progression in a Lethal Mousepox Model Treated with CMX001

Background

The emergence of human monkeypox and the potential use of recombinant variola and monkey-pox viruses as biological terrorist agents have necessitated the development of therapeutic and prophylactic therapies. The primary, or index, cases of smallpox and/ or human monkeypox will likely be identified by a characteristic rash. Effective biomarkers will be required to monitor disease progression, guide the choice of therapeutic intervention strategies and evaluate their efficacies. To address this we have evaluated several biomarkers of disease in a lethal mousepox model.

Methods

The efficacy of a single dose of a hexadecyloxypropyl ester of cidofovir (CMX001) at 20, 25 and 30 mg/ kg doses administered on days 4, 5, 6 and 7 post-infection was evaluated in A/Ncr mice intranasally infected with low doses of ectromelia virus (<20 plaque-forming units). Mice were monitored for weight loss, blood interferon-γlevels, alanine aminotransferase (ALT), aspartate amino-transferase, viral DNA copies and neutrophilia levels to stage disease progression.

Results

We have used these biomarkers to establish the optimal dosing regimen for treatment and reveal that a single dose of 25 mg/kg of CMX001 can be efficacious at treating lethal mousepox when administered on days 4 or 5 post-infection. This dose significantly reduces ALT, interferon-γand DNA copies found in the blood of infected animals.

Conclusions

A single dose regimen of CMX001 is efficacious at treating mousepox. Disease progression and antiviral efficacy can be monitored using several biomarkers that could readily be used in the case of a human monkeypox or smallpox outbreak.

[Extensive oral condylomas treated by in situ cidofovir injection in an HIV patient]

BACKGROUND

Human papillomavirus infections are difficult to treat and have a high rate of recurrence, especially in a setting of human immunodeficiency (HIV) infection. Moreover, there is no standard treatment for oral condylomas.

PATIENTS AND METHODS

We report the partial success of in situ injections of cidofovir in an HIV patient, presenting extensive oral condylomas. The injections were well tolerated and the response was still present at one year while the immune status of the patient was unchanged.

DISCUSSION

The efficacy of topical cidofovir against condyloma acuminata has been reported and the value of in situ cidofovir injections for the treatment of laryngeal papillomatosis is well established. This case report shows the need for further investigation of in situ cidofovir injections as an alternative treatment for human papillomavirus lesions that are difficult to treat because of both site and extension.

Efficacy of therapeutic intervention with an oral ether-lipid analogue of cidofovir (CMX001) in a lethal mousepox model

In the 21st century we are faced with the potential use of natural or recombinant VARV and MPXV as biological weapons, and the emergence of human MPXV. Such an occurrences would require therapeutic and prophylactic intervention with antivirals. Cidofovir, an antiviral approved for the treatment of cytomegalovirus retinitis in AIDS patients, has activity against poxviruses, but must be administered intravenously and is associated with nephrotoxicity. An ether-lipid analogue of CDV, CMX001 (HDP-CDV), has potent antiviral activity against a range of DNA viruses including poxviruses, excellent oral bioavailability and minimal nephrotoxicity. CMX001 and CDV are equally efficacious at protecting mice from mortality following high ectromelia virus doses (10,000 x LD(50)) introduced by the intra-nasal route or small particle aerosol. Using CMX001 at a 10mg/kg dose followed by 2.5mg/kg doses every other-day for 14 days provided solid protection against mortality and weight loss following an intra-nasal challenge of (100-200) x LD(50) of ectromelia virus. Furthermore, complete protection against mortality was achieved when administration was delayed until as late as 5 days post-infection, which is 3-4 days prior to the death of the untreated controls. This therapeutic window would be equivalent to intervening during the rash stage of ordinary smallpox.

The design and development of drugs acting against the smallpox virus

The eradication of smallpox was announced by the WHO in 1980. However, smallpox has not totally disappeared from people's minds because of its potential use as a biological weapon. Further outbreaks of smallpox would, needless to say, be devastating in a population, which has little or no immune defence against the virus. The real concerns come from the fact that the previously used vaccine would not be tolerated today by a number of patients and, more worryingly, there are no approved antiviral drugs against smallpox. This review is focused on the antiviral research, which has been stimulated to deliver potent inhibitors of the replication of the causative agent of smallpox, variola virus.

Acute meningoencephalitis caused by adenovirus serotype 26

Adenoviridae are rare causes of meningoencephalitis in both immunocompetent and immunocompromised hosts. In this article the authors report a case of adenoviral meningoencephalitis caused by serotype 26 and its identification, not described previously, in cerebrospinal fluid (CSF) by PCR and brain tissue by immunohistochemical staining.

Pivotal role of animal models in the development of new therapies for cytomegalovirus infections

Since human cytomegalovirus (CMV) is extremely species specific and does not replicate in experimental animal tissues, animal models for the evaluation of antiviral agents for these infections have utilized surrogate animal viruses including murine CMV, rat CMV and guinea pig CMV. Murine CMV and rat CMV infections in normal and immunocompromised animals provide models of disseminated infection and are ideal for screening of new agents. While guinea pig CMV infection in immunocompromised animals also provides a model for disseminated disease, the model for congenital CMV is unique among all the experimental models. While these models have played a major role in the development of ganciclovir, foscarnet and cidofovir, they do not provide information directly related to human CMV, nor are they useful for evaluation of agents that are active only against human CMV. The SCID-hu mouse models in which human tissue is infected with human CMV has been very useful in the development of new antiviral agents such as maribavir and cyclopropavir. Collectively these experimental CMV infections provide a variety of models representing various aspects of CMV infection in humans that are highly predictive for antiviral efficacy in humans.

Inhibitory efficacy of cyclosal-nucleoside monophosphates of aciclovir and brivudin on DNA synthesis of orthopoxvi ruses

Previous studies have shown that cycloSaligenyl-monophosphate (cycloSal-MP) derivatives of aciclovir (ACV), penciclovir (PCV) and brivudin (BVDU) can act as inhibitors of vaccinia virus and cowpox virus replication in vitro. The aim of the present study was to evaluate the inhibatory efficacy on DNA synthesis in vaccinia and cowpox viruses of several cycloSal-pro-nucleotides of ACV and BVDU, which have proven activity against pox viruses. Viral DNA was quantified in treated and non-treated virus-infected cells by semi-quantitative PCR on the basis of the haemagglutinin protein gene of orthopoxviruses. As result, an inhibitory efficacy on vaccinia and cowpox virus DNA replication could be demonstrated for 3-methyl-cycloSal-ACVMP, 5-H-cycloSal-ACVMP, 6-chloro-7-ECM-cycloSal-3'-OH-BVDUMP, and 6-chloro-7-methyl-cycloSal-3'-OH-BVDUMP. At concentrations of 32-128 mg/ml, 3-methyl-cyc/oSal-ACVMP and 6-chloro-7-ECM-cycloSal-3'OH-BVDUMP inhibited synthesis of viral DNA to a similar extent as the well-known inhibitors of pox viruses, cidofovir and 5-iodo-dUrd (deoxyuridine). When concentrations of 128 mg/ml were administered, both test substances diminished the amount of viral genome copies by > or =4 log10 corresponding to > or =99.99% reduction. In conclusion, selected cycloSal-pro-nucleotide derivatives of ACV and BVDU can inhibit orthopoxviral DNA synthesis. The high inhibitory efficacy on both replication of viral DNA and infectious viral particles in cell cultures makes these compounds promising candidates for in vivo experiments.

Viral mRNA expression but not DNA replication is required for lipogenic effect of human adenovirus Ad-36 in preadipocytes

OBJECTIVE

Human adenovirus Ad-36 causes adiposity in animal models and shows association with human obesity. Ad-36 enhances differentiation of 3T3-L1 and human preadipocytes, without cell lysis, a characteristic that may contribute to its adipogenic effect observed in vivo. Ad-2, another human adenovirus is nonadipogenic in animals and in 3T3-L1 cells and shows no correlation with human obesity. The objective of this study was to determine the adipogenic roles of viral mRNA and DNA, which may explain the differential effects of Ad-36 and Ad-2 on preadipocyte differentiation.

METHODS

This study determined the duration of selected Ad-36 gene expression in 3T3-L1 cells, and the effect on preadipocytes differentiation, when Ad-36 gene expression was attenuated by Cidofovir, an antiadenoviral agent.

RESULTS

The results showed that Ad-36, but not Ad-2, expresses viral mRNA. Ad-36 gene expression peaked at 2-4 days postinoculation and very low levels persisted after day 7. Despite the viral mRNA expression, Ad-36 infection of 3T3-L1 cells was abortive as indicated by a progressive decrease in viral DNA quantity. Attenuation of Ad-36 mRNA expression by Cidofovir reduced the adipogenic effect of the virus.

CONCLUSION

In conclusion, viral mRNA expression, although transient, is a prerequisite for enhancing differentiation of preadipocytes by Ad-36. Viral DNA replication was not required for the effect. This is the first evidence for the role of gene expression of an adipogenic human virus in enhancing preadipocytes differentiation. This study provides the basis for further understanding novel regulatory modulators of preadipocytes differentiation.

Actualización en el tratamiento del herpes zóster

The systemic treatment of herpes zoster shortens the healing process, and prevents or alleviates pain and other acute or chronic complications, especially when it is administered in the first 72 hours after symptoms appear. This treatment is especially indicated in patients over the age of 50 and in those who, regardless of age, have head and neck involvement, especially in herpes zoster ophthalmicus. The drugs approved in Europe for the systemic treatment of herpes zoster are aciclovir, valaciclovir, famciclovir and brivudine. Brivudine shows greater effectiveness against the varicella-zoster virus than aciclovir and its derivatives, and can be given just once a day for seven days, compared to multiple doses of the latter. As opposed to the others, brivudine is a non-nephrotoxic drug that should not be administered to immunodepressed patients or to those being treated with 5-fluorouracil. The treatment of herpes zoster to reduce pain should be combined with analgesics and neuroactive agents (amitriptyline, gabapentin, etc). While corticosteroids are of dubious efficacy in the treatment of post-herpes neuralgia, the intensity and duration of the pain can be reduced with some topical treatments (capsaicin, lidocaine patches, etc). Finally, this review discusses treatment guidelines for special locations (cranial nerves) and different subpopulations (children, pregnant women, immunodepressed patients, etc).

A survey of antiviral drugs for bioweapons

Smallpox (variola major), and the haemorrhagic fever viruses (filoviruses and arenaviruses) are classified as Category A biowarfare agents by the Centers for Disease Control. Category A agents pose a significant risk to public health and national security because they can be easily disseminated by aerosol, although with the exception of variola, they are not easily transmitted from person to person. An attack with these viruses would result in high morbidity and mortality and cause widespread panic. With the exception of smallpox and Argentine haemorrhagic fever virus, there are no vaccines or approved treatments to protect against these diseases. In this review we focus on promising prophylactic, therapeutic and disease modulating drugs (see Figure 1 for select chemical structures).

Comparative activities of lipid esters of cidofovir and cyclic cidofovir against replication of herpesviruses in vitro

Cidofovir (CDV) is an effective therapy for certain human cytomegalovirus (HCMV) infections in immunocompromised patients that are resistant to other antiviral drugs, but the compound is not active orally. To improve oral bioavailability, a series of lipid analogs of CDV and cyclic CDV (cCDV), including hexadecyloxypropyl-CDV and -cCDV and octadecyloxyethyl-CDV and -cCDV, were synthesized and found to have multiple-log-unit enhanced activity against HCMV in vitro. On the basis of the activity observed with these analogs, additional lipid esters were synthesized and evaluated for their activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus, murine cytomegalovirus, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and HHV-8. Using several different in vitro assays, concentrations of drug as low as 0.001 microM reduced herpesvirus replication by 50% (EC50) with the CDV analogs, whereas the cCDV compounds were generally less active. In most of the assays performed, the EC50 values of the lipid esters were at least 100-fold lower than the EC50 values for unmodified CDV or cCDV. The lipid analogs were also active against isolates that were resistant to CDV, ganciclovir, or foscarnet. These results indicate that the lipid ester analogs are considerably more active than CDV itself against HSV, VZV, CMV, EBV, HHV-6, and HHV-8 in vitro, suggesting that they may have potential for the treatment of infections caused by a variety of herpesviruses.

Prospects for adenovirus antivirals

Adenoviruses cause a number of self-limiting but often highly infectious diseases that affect multiple organs, most commonly those associated with respiratory, genitourinary and gastrointestinal tracts and the ocular surface. Many factors have driven a search for effective topical and systemic antivirals to adenoviruses. These include patient morbidity, economic losses and chronic visual disturbances associated with epidemic keratoconjunctivitis; and the startling recent trend of high morbidity and rising mortality associated with systemic adenoviral infections in the immunosuppressed, particularly paediatric bone marrow transplant recipients. The development of effective antivirals has proven to be a complex task, owing to the fact that multiple and often genetically divergent adenovirus serotypes can cause similar diseases. Currently, there remains no licensed systemic or topical treatment in the USA or Europe. However, many compounds have been explored for activity against adenoviruses, and some have been evaluated clinically in either a topical setting for ocular disease or in the setting of systemic treatment in the face of life-threatening adenovirus infections. This article outlines such compounds, discusses the potential for their clinical development, and highlights some problems that may be faced in evaluating their efficacy clinically.

Emerging therapies for herpes viral infections (types 1 – 8)

There are eight members of the herpesviridae family: herpes simplex virus-1 (HSV-1), HSV-2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, human herpes virus-6, human herpes virus-7 and human herpes virus-8. The diseases caused by viruses of the herpesviridae family are treated with and managed by systemic and topical antiviral therapies and immunomodulating drugs. Because these viruses establish a latent state in hosts, antiherpetic agents, such as nucleoside analogues, only control symptoms of disease or prevent outbreaks, and cannot cure the infections. There is a need for treatments that require less frequent dosing, can be taken even when lesions are more advanced than the first signs or symptoms, and can treat resistant strains of the viruses without the toxicities of existing therapies. Immunomodulating agents, such as resiquimod, can act on the viruses indirectly by inducing host production of cytokines, and can thereby reduce recurrences of herpes. The new helicase primase inhibitors, which are the first non-nucleoside antiviral compounds, are being investigated for treatment of HSV disease, including infections resistant to existing therapy.

Oral activity of a methylenecyclopropane analog, cyclopropavir, in animal models for cytomegalovirus infections

We reported previously that purine 2-(hydroxymethyl)methylenecyclopropane analogs have good activity against cytomegalovirus infection. A second-generation analog, (Z)-9-[[2,2-bis-(hydroxymethyl)cyclopropylidene]methyl]guanine (ZSM-I-62, cyclopropavir [CPV]), has particularly good activity against murine and human cytomegaloviruses (MCMV and HCMV) in vitro. To determine the oral activity of this compound in vivo, BALB/c or severe combined immunodeficient (SCID) mice infected with MCMV and two models using SCID mice implanted with human fetal tissue and subsequently infected with HCMV were used. In MCMV-infected normal mice, CPV at 10 mg/kg of body weight was highly effective in preventing mortality when administered at 24, 48, or 72 h post-viral inoculation and reduced titers of virus in tissues of SCID mice by 2 to 5 log10. In one HCMV model, human fetal retinal tissue was implanted into the anterior chamber of the mouse eye and inoculated with the Toledo strain of HCMV, and in the second, human fetal thymus and liver tissues were implanted under the kidney capsule of mice and then inoculated with HCMV. In general, replication of HCMV in both types of implant tissue increased from 7 through 21 to 28 days and then gradually decreased to undetectable levels by 8 weeks postinfection. Oral treatment with 45 or 15 mg of CPV/kg initiated 24 h after infection was highly effective in reducing replication to undetectable levels in both models and was generally more effective than ganciclovir. These data indicate that the methylenecyclopropane analog, CPV, was highly efficacious in these four animal models and should be evaluated for use in HCMV infections in humans.

[Varicella-zoster virus infections]

The primary infection with varicella-zoster virus (VZV) is manifest clinically as varicella. It is a common very contagious disease, normally appearing in childhood. VZV is a ubiquitous virus with a high prevalence. Clinically it is characterized by pleomorphic skin lesions. Normally antiviral therapy is necessary only in severe cases, in adults or in immunosuppressed patients. Herpes zoster, also caused by (VZV), is a neurodermal disease representing the endogenous relapse of the primary varicella infection. Herpes zoster is characterized by lesions concentrated in the innervation region of a cranial or spinal nerve. One of the most feared manifestations of herpes zoster is pain. Several antiviral drugs are approved and many studies have shown that antiviral therapy, started early in the course of disease, can significantly reduce risk and duration of postherpetic neuralgia in elderly patients. Therefore, antiviral therapy in combination with an adequate pain management should be given to all elderly patients as soon as herpes zoster is diagnosed.

Oral treatment of murine cytomegalovirus infections with ether lipid esters of cidofovir

To improve the oral bioavailability of cidofovir (CDV), a series of ether lipid ester prodrugs were synthesized and evaluated for activity against murine cytomegalovirus (MCMV) infection. Four of these analogs, hexadecyloxypropyl (HDP)-CDV, octadecyloxyethyl (ODE)-CDV, oleyloxyethyl (OLE)-CDV, and oleyloxypropyl (OLP)-CDV, were found to have greater activity than CDV against human CMV and MCMV in vitro. The efficacy of oral treatment with these compounds against MCMV infections in BALB/c mice was then determined. Treatment with HDP-CDV, ODE-CDV, OLE-CDV, or OLP-CDV at 2.0 to 6.7 mg/kg of body weight provided significant protection when daily treatments were initiated 24 to 48 h after viral inoculation. Additionally, HDP-CDV or ODE-CDV administered twice weekly or as a single dose of 1.25 to 10 mg/kg was effective in reducing mortality when treatment was initiated at 24 h, 48 h, or, in some cases, 72 h after viral inoculation. In animals treated daily with HDP-CDV or ODE-CDV, virus titers in lung, liver, spleen, kidney, pancreas, salivary gland, and blood were reduced 3 to 5 log(10)-fold, which was comparable to CDV given intraperitoneally. These results indicated that HDP-CDV or ODE-CDV given orally was as effective as parenteral CDV for the treatment of experimental MCMV infection and suggest that further evaluation for use in CMV infections in humans is warranted.

Cidofovir for treating adenoviral hemorrhagic cystitis in hematopoietic stem cell transplant recipients

Adenovirus (AdV) infection is an important cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. We treated 16 patients with AdV hemorrhagic cystitis (HC) following HSCT with cidofovir (CDV; 1 mg/kg/day, three times weekly for 3 weeks). Patients included 10 males and six females with a median age of 50 years (range 10-62). Two of the 16 patients were unevaluable because of early death from nonadenoviral causes. CDV therapy cleared AdV from urine in 12 of 14 patients (86%). Of 14 patients, 10 (71%) showed clinical improvements in HC. Among 14 patients, seven (50%) had avoided renal damage, the most important CDV toxicity. One patient previously treated with foscarnet for cytomegalovirus (CMV) required hemodialysis, and CDV treatment was discontinued. In another patient, CDV treatment was discontinued because of grade 2 nephrotoxicity. Four patients became positive for CMV antigenemia while being treated with CDV, and two developed herpes simplex virus (HSV) stomatitis while being treated with CDV. CDV proved effective in treating AdV HC in transplant patients. However, CDV at 1 mg/kg/day given three times weekly failed to prevent breakthrough infection with CMV and HSV in some patients.

Antivirals and antiviral strategies

In recent years, the demand for new antiviral strategies has increased markedly. There are many contributing factors to this increased demand, including the ever-increasing prevalence of chronic viral infections such as HIV and hepatitis B and C, and the emergence of new viruses such as the SARS coronavirus. The potential danger of haemorrhagic fever viruses and eradicated viruses such as variola virus being used as bioterrorist weapons has also increased the profile of antiviral drug discovery. Here, the virus infections for which antiviral therapy is needed and the compounds that are available, or are being developed, for the treatment of these infections are described.

Traitement par cidofovir topique d’infections cutanées à papillomavirus humain, poxvirus et Herpes simplex virus chez des malades séropositifs pour le VIH

INTRODUCTION

Cidofovir (Vistide) is an antiviral marketed for the treatment of cytomegalovirus retinitis. Clinical efficacy has been reported with its broad antiviral spectrum that includes poxvirus, human papilloma virus and Herpes simplex. In immunodepressed patients, these infectious dermatoses are often recurrent and resistant. In an open study, we assessed the efficacy and clinical tolerance of cidofovir gel at 1 p. 100.

PATIENTS AND METHODS

Twelve HIV-infected adults were included. Cidofovir gel at 1 p. 100 was applied directly on the lesions, once a day, for two weeks on the molluscum and condylomas, four weeks on the warts and one week on the chronic herpes.

RESULTS

Four patients presented with warts and 3 of them with verruca plana. In 2 of the verruca plana patients, regression was complete although relapse was observed. Two failures were noted. Local application of the gel was not tolerated by one patient suffering from condylomas of the penis. Four patients presented with molluscum contagiosum. Two complete regressions with strong local reaction and two partial regressions were observed. The latter two patients exhibited severe immunodepression, one of them subsequently received infusions of cidofovir. Two women suffering from vulvar and perianal herpes resistant to acyclovir were treated for one week with cidofovir gel at 1 p. 100: no response was obtained. One of the patients stopped treatment because of local intolerance. A third, less immunodepressed, woman responded partially.

COMMENTS

In HIV-positive patients, cidofovir in topical form appears to be indicated in extensive and confluent molluscum contagiosum. However, the effect occurs at the cost of local inflammation. The results are disappointing in papillomavirus lesions and in chronic acyclovir-resistant herpes ulcerations, efficacy is debatable.

Recurrent respiratory papillomatosis: Cytopathological findings in an unusual case

Recurrent respiratory papillomatosis (RRP) primarily is a disease of children and adolescents. Most patients experience spontaneous regression at a later age, while others continue to be affected throughout their lives. Here, we present the case of a 26-yr-old man who presented with persistent cough, worsening dyspnea, and development of pneumothorax. Eight years prior, he had presented with similar complaints and an evaluation at that time had showed RRP. Follow-up since that time showed recurrent disease managed by multiple surgical procedures. At the most current admission, an ultrasound-guided fine-needle aspiration (FNA) of the lung showed numerous papillary tissue fragments and single atypical squamous cells consistent with recurrent RPR. To our knowledge, morphological findings of RRP have been reported rarely.

Herpes zoster guideline of the German Dermatology Society (DDG)

Varicella zoster virus (VZV) causes varicella (chickenpox), remains dormant in dorsal root and cranial nerve ganglia and can be reactivated as a consequence of declining VZV-specific cellular immunity leading to herpes zoster (shingles). Patients older than 50 years of age affected by herpes zoster may suffer a significant decrease of quality of life. These patients and immunocompromised individuals are at increased risks for severe complications, involving the eye, the peripheral and the central nervous system (prolonged pain, postherpetic neuralgia). Such complications occur with and without cutaneous symptoms. The German Dermatology Society (DDG) has released guidelines in order to guarantee updated management to anyone affected by herpes zoster. Diagnosis is primarily clinical. The gold standard of laboratory diagnosis comprises PCR and direct identification of VZV in cell cultures. Detection of IgM- and IgA-anti VZV antibodies may be helpful in immunocompromised patients. Therapy has become very effective in the last years. Systemic antiviral therapy is able to shorten the healing process of acute herpes zoster, to prevent or to alleviate pain and other acute and chronic complications, particularly, when given within 48 h to a maximum of 72 h after onset of the rash. Systemic antiviral therapy is urgently indicated in patients beyond the age of 50 years and in patients at any age with herpes zoster in the head and neck area, especially in patients with zoster ophthalmicus. Further urgent indications are severe herpes zoster on the trunk and on the extremities, herpes zoster in immunosuppressed patients and in patients with severe atopic dermatitis and severe ekzema. Only relative indications for antiviral therapy exist in patients younger than 50 years with zoster on the trunk and on the extremities. In Germany acyclovir, valacyclovir, famciclovir and brivudin are approved for the systemic antiviral treatment of herpes zoster. These compounds are all well tolerated by the patients and do not differ with regard to efficacy and safety. Brivudin has a markedly higher anti-VZV potency than oral acyclovir, valacyclovir and famciclovir and thus offers a simpler dosing regimen. It must be given only once daily during 7 days in comparison to three and five times dosing per day of valacyclovir, famciclovir and acyclovir, respectively. Brivudin is an antiviral agent with no nephrotoxic properties, which is an advantage when compared to acyclovir. The most important aim of therapy of herpes zoster is to achieve painlessness. Appropriately dosed analgesics in combination with a neuroactive agent (i.e. amitriptylin) are very helpful when given together with antiviral therapy. The additive therapy with corticosteroids may shorten the degree and duration of acute zoster pain, but has no essential effect on the development of postherpetic neuralgia, which is a very difficult condition to treat. Thus early presentation to a pain therapist is recommended in specific cases.

Synergy of bovine lactoferrin with the anti-cytomegalovirus drug cidofovir in vitro

Human cytomegalovirus (HCMV) causes severe morbidity and mortality in immunocompromised patients. Treatment of HCMV infections with conventional antiviral drugs like ganciclovir and cidofovir has major drawbacks (i.e. serious side effects). Therefore, combination therapies using drugs with different antiviral mechanisms should be envisaged. Potential synergy between lactoferrin (LF), an antibacterial, antimycotic and antiviral protein, and the antiviral drugs acyclovir, ganciclovir, foscarnet and cidofovir was investigated, using an in vitro test system with the recombinant RC256 HCMV strain.

RESULTS

Combination of LF with acyclovir and foscarnet resulted in antagonism. When LF and ganciclovir were combined, neither synergy nor antagonism was observed. Strikingly, the combination of LF with cidofovir resulted in marked synergy. The synergistic effect could be explained by inhibition of two subsequent steps in the viral replication cycle: HCMV penetration into the target cells and intracellular synthesis of HCMV DNA. In conclusion, LF might be a potential candidate for combination therapy with cidofovir.

In vitro activity of potential anti-poxvirus agents

The potential use of variola or another orthopoxvirus such as monkeypox as a weapon of bioterrorism has stimulated efforts to develop new drugs for treatment of smallpox or other poxvirus infections. At the present time only cidofovir is approved for use in the emergency treatment of smallpox outbreaks. Although cidofovir is very active against the orthopoxviruses in vitro and in animal model infections, it is not active when given orally and must be administered with precaution so as to avoid renal toxicity. In an attempt to identify alternative treatment modalities for these infections we have determined the anti-poxvirus activity in vitro of most of the approved antiviral agents as well as a number of cidofovir analogs and prodrugs. From these studies, we have identified the nucleotide analog, adefovir dipivoxil, some alkoxyalkyl esters of cidofovir and a number of prodrugs of cidofovir that warrant further investigation as potential therapies for smallpox or other orthopoxvirus infections.

Molluscum contagiosum: recent advances in pathogenic mechanisms, and new therapies

Two poxviruses, Molluscum contagiosum virus (MCV) and Variola virus are specific to humans. MCV is present worldwide and is directly passed by direct skin to skin contact to produce cutaneous and, rarely, mucosal lesions. It occurs predominantly in preadolescent children, sexually active adults, participants in sports with skin to skin contact, and in individuals with impaired cellular immunity. MCV characteristically proliferates within the follicular epithelium, and with routine fixation produces an area of retraction artifact separating layers 1 to 3 of CD34+ stromal cells that immediately surround the follicle from the surrounding dermis. This feature may be obscured when the lesions are inflamed, usually after rupture into the surrounding dermis. MCV is a cytoplasmically replicating virus. MCV-infected cells grow in size, while internal organelles are dislocated and eventually obliterated by a large intracytoplasmic inclusion. Rupture and discharge of the virus-packed cells occurs in a process similar to membrane debris and MCV accumulate in the crater-like ostium; MCV infection is spread by contact with infectious debris. In HIV-1-positive patients the histologic features, as well as the clinical features, may be atypical in patients with MCV infections. Not only are the lesions often large, but they may be verrucous and markedly hyperkeratotic. Recent sequencing of the MCV genome has increased our understanding and investigations into its mechanisms for avoiding host defense mechanisms. These include regions which encode for homologues of cellular chemokines and chemokine-binding proteins, a homolog of MHC1 and a viral FLICE-like inhibitory protein. Treatment, until recently, has depended upon tissue destruction including curettage, cryotherapy, CO(2) laser, electrodesiccation, trichloracetic acid and cantharadin. Recently, topical immune modulators have been used with some success. Understanding of the MCV genome is providing the basis for the development of drugs for therapy and prevention of MCV infections.

Antivaccinia activities of acyclic nucleoside phosphonate derivatives in epithelial cells and organotypic cultures

Organotypic "raft" cultures of epithelial cells allow the reconstitution of a skin equivalent that is easily infectible with different viruses with cutaneous tropism. Among these, poxvirus and particularly vaccinia virus (VV) are good candidates for use in antiviral tests, giving histological pictures comparable to those observed in humans infected with smallpox. Therefore, we decided to evaluate a series of phosphonate derivatives for their ability to inhibit VV growth in epithelial cell monolayers, and the most powerful derivatives were tested in the organotypic cultures. The most active compound was 9-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine [(S)-HPMPA], followed by 9-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]-2,6-diaminopurine, cyclic (S)-HPMPA, 9-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine [(S)-HPMPC; cidofovir, Vistide], and cyclic (S)-HPMPC. Cidofovir, which is on the market for the treatment of human cytomegalovirus retinitis in immunocompromised patients, is potentially a good candidate for the treatment of a poxvirus outbreak, in the absence of any vaccination.

Intravenous Cidofovir therapy for disseminated adenovirus in a pediatric liver transplant recipient

BACKGROUND

No definitive antiviral therapy exists for adenovirus (ADV) in immunosuppressed hosts. Cidofovir (CDV), a broad spectrum anti-DNA viral agent, has previously been shown to be of therapeutic benefit in life-threatening adenoviral disease in bone marrow stem-cell recipients.

METHODS

A 71/2-month-old girl with a history of biliary atresia developed fevers, hematochezia, tachypnea, and laboratory evidence of hepatitis and pancreatitis 12 days after liver transplantation. A stool culture, oropharyngeal culture, blood viral culture, and blood polymerase chain reaction (PCR) confirmed ADV. Cidofovir 1 mg/kg intravenously three times per week was initiated. The patient received intravenous hydration and probenecid with the infusions to reduce the nephrotoxicity of CDV. Immunosuppression was reduced to achieve tacrolimus trough levels of approximately 8 ng/mL and prednisone at 0.1 mg/kg per day. Complete blood cell count, urinalysis, and viral studies were obtained weekly.

RESULTS

Detection of ADV DNA by PCR made a transition from positive to negative during CDV therapy. Blood viral cultures became negative after two CDV doses. Alanine aminotransferase normalized by 5 weeks of therapy. CDV was discontinued after 7 weeks secondary to transient acidosis and proteinuria. The patient never developed azotemia, neutropenia, or ocular abnormalities.

CONCLUSIONS

CDV was associated with improved clinical status, viral clearance, and minimal transient side effects in a pediatric liver transplant recipient with disseminated adenoviral disease. The current report documents clearance of disseminated ADV infection in a liver transplant recipient receiving CDV infusions.

Cidofovir in the therapy and short-term prophylaxis of poxvirus infections

Although it is often stated that only vaccination would be able to contain or protect the population against a catastrophic smallpox outbreak, the acyclic nucleoside phosphonate analog cidofovir offers a valuable alternative for the therapy and short-term pre- and post-exposure prophylaxis, not only of smallpox but also of other poxvirus infections and DNA viruses. Cidofovir has proven effective against vaccinia, cowpox and monkeypox in various animal model infections. In cell culture, cidofovir has demonstrated activity against variola virus, the etiological agent of smallpox, and in patients it has shown marked efficacy against molluscum contagiosum and orf, two poxvirus infections. Cidofovir is available as an aqueous solution for intravenous administration and could be reformulated for topical (cream or gel), intranasal (aerosol) or peroral (as a lipid prodrug) use, should the need arise.

Antiviral agents: Nonantiviral drugs

The current arsenal of antiviral agents available to the practitioner is expanding rapidly, such that by the time this article goes to press, new drugs may have already been added. Although the majority of approved drugs have been developed for use in only a few viral infections (eg, HIV, herpesviruses, and papillomavirus), discoveries made in the development of these drugs may lead to antiviral agents effective against other viruses. In addition, new uses for the currently available drugs are under evaluation. This review of antiviral agents discusses the treatments available for viral infections such as herpes simplex virus, varicella zoster virus, cytomegalovirus, human papillomavirus, chronic viral hepatitis, and others.

Human herpesvirus 7 in dermatology: what role does it play?

Human herpesvirus 7 (HHV-7) was discovered in 1989 as a new member of the beta-herpesvirus subfamily. Primary infection occurs early in life and manifests as exanthema subitum, or other febrile illnesses mimicking measles and rubella. Thus, HHV-7 has to be considered as a causative agent in a variety of macular-papular rashes in children. In addition, HHV-7 was found in some cases of other inflammatory skin disorders, such as psoriasis. There are controversial data on the detection of HHV-7 in pityriasis rosea, but so far there is not enough evidence for a pathogenetic association of HHV-7 with this exanthematic skin disease. Although HHV-7 can be found in some cases of Hodgkin's disease, there are no data supporting a direct causative role in this lymphoma type nor in other nodal or primary cutaneous lymphomas. In various epidemiologic forms of Kaposi's sarcoma, infection of monocytic cells with HHV-7 was demonstrated, which may indirectly influence tumor biology. In the context of immunosuppression, HHV-7 has recently been identified as an emerging pathogen in transplant recipients and may exacerbate graft rejection in renal transplant recipients. The ability of HHV-7 to induce cytokine production in infected cells could make HHV-7 an important pathogenetic co-factor in inflammatory and neoplastic disorders. Moreover, the restricted cellular tropism of HHV-7 may render this virus an interesting vector for gene therapy. Thirteen years after the discovery of HHV-7, there has been considerable progress in characterizing its genetic structure, virus-induced effects on infected host cells and in the development of diagnostic tools. Nevertheless, the role of HHV-7 in various skin diseases and the clinical manifestations of reactivation of HHV-7 infection have still to be defined.

Cidofovir in the treatment of poxvirus infections

Cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine, HPMPC] has since 1996 been licensed for clinical use in the treatment of cytomegalovirus (CMV) retinitis in AIDS patients. Cidofovir has broad-spectrum activity against virtually all DNA viruses, including herpes-, adeno-, polyoma-, papilloma- and poxviruses. Among the poxviruses, vaccinia, variola (smallpox), cowpox, monkeypox, camelpox, molluscum contagiosum and orf have proven sensitive to the inhibitory effects of cidofovir. In vivo, cidofovir has shown high efficacy, even after administration of a single systemic (intraperitoneal) or intranasal (aerosolized) dose, in protecting mice from a lethal respiratory infection with either vaccinia or cowpox. Cidofovir has also demonstrated high effectiveness in the treatment of vaccinia virus infection in severe combined immune deficiency mice. In humans, cidofovir has been used successfully in the treatment, by both the topical and intravenous route, of recalcitrant molluscum contagiosum and orf in immunocompromised patients. Taken together, these data indicate that cidofovir should be effective in the therapy and short-term prophylaxis of smallpox and related poxvirus infections in humans, as well as the treatment of the complications of vaccinia that may arise in immunocompromised patients inadvertently inoculated with the smallpox vaccine (vaccinia).

Local treatment of HPV-induced skin lesions by Cidofovir

Human papillomavirus (HPV) induced epithelial cell proliferation is responsible for a broad range of lesions. Treatment of such lesions is characterized by a high relapse rate. Four patients are described who were treated locally with cidofovir (cream 1% or injection of 2.5 mg/ml solution) for multi-treated relapsing HPV-associated lesions. Three of the four patients had a complete response. The fourth patient showed a clinical response in the first cycle of treatment, but new lesions appeared during four successive cycles of cidofovir.

Office-based treatment of laryngeal papillomatosis with percutaneous injection of cidofovir

OBJECTIVE

Our aim was to report our experience with office-based treatment of severe laryngeal papillomatosis with percutaneous injection of cidofovir in a case series of 5 patients.

STUDY DESIGN AND SETTING

We conducted a retrospective review of a case series in a tertiary academic care voice disorders clinic. Adult patients with papillomas of the vocal cords and anterior commissure received percutaneous injection using a point-touch technique. Clinical improvement or remission of the papillomatosis was noted.

RESULTS

Before initiation of office treatments, patients required direct laryngoscopy and CO(2) laser ablation of papillomas on average every 2.8 months. There were no complications related to the injection technique. During a treatment period of 7 to 16 months (mean 12 months), a significant reduction in the volume of papillomatosis was achieved in all patients. One patient received 2 treatments and another received 1 treatment in the operating room for final clearance of papillomas.

CONCLUSION

Office-based treatment of adult patients with anterior laryngeal papillomatosis using percutaneous injection of cidofovir reduces the need for repeated direct laryngoscopy and laser ablation under general anesthesia.

SIGNIFICANCE

Percutaneous injection treatment with cidofovir is a useful adjunct to direct laryngoscopy and laser ablation in the treatment of laryngeal papillomatosis.

Antiviral agent Cidofovir restores p53 function and enhances the radiosensitivity in HPV-associated cancers

High-risk human papillomaviruses (HPVs) have been associated to the development of cervical and some other human cancers. Most of them express E6 and E7 oncoproteins, able to bind to p53 and retinoblastoma (pRb) tumor suppressor proteins respectively and neutralize their function. Restoration of these pathways by blocking E6 and E7 expression would provide a selective therapeutic effect. Here, we show that a clinically approved antiviral agent Cidofovir reduced E6 and E7 expression in cervical carcinoma Me180 and head and neck squamous cell carcinoma HEP2 cells at the transcriptional level. Cidofovir induced the accumulation of active p53 and pRb associated to induction of cyclin dependent kinase inhibitor p21(WAF1/CIP1) in Me180 and HEP2 cells. p53 induction was also shown in Hela HPV-positive cervical carcinoma cell line. In addition, S phase cell cycle accumulation with concomitant decrease of cyclin A expression were associated to the antiproliferative activity of Cidofovir in HPV-treated cells. Combining Cidofovir to irradiation both in vivo and in nude mice xenografts resulted in a marked radiosensitization in HPV-positive cells, which was not observed in virus negative cells. This study provides the basis for a new anticancer strategy to enhance the antitumor effect of ionizing radiation in HPV-related cancers, without increase deleterious effects.

Enhanced inhibition of orthopoxvirus replication in vitro by alkoxyalkyl esters of cidofovir and cyclic cidofovir

The nucleotide phosphonates cidofovir (CDV) and cyclic cidofovir (cCDV) are potent antiviral compounds when administered parenterally but are not well absorbed orally. These compounds have been reported to have activity against orthopoxvirus replication in vitro and in animal models when administered parenterally or by aerosol. To obtain better oral activity, we synthesized a novel series of analogs of CDV and cCDV by esterification with two long-chain alkoxyalkanols, 3-hexadecyloxy-1-propanol (HDP-CDV; HDP-cCDV) or 3-octadecyloxy-1-ethanol (ODE-CDV; ODE-cCDV). Their activities were evaluated and compared with those of CDV and cCDV in human foreskin fibroblast (HFF) cells infected with vaccinia virus (VV) or cowpox virus (CV) using a plaque reduction assay. The 50% effective concentrations (EC(50)s) against VV in HFF cells for CDV and cCDV were 46.2 and 50.6 microM compared with 0.84 and 3.8 microM for HDP-CDV and HDP-cCDV, respectively. The EC(50)s for ODE-CDV and ODE-cCDV were 0.20 and 1.1 microM, respectively. The HDP analogs were 57- and 13-fold more active than the parent nucleotides, whereas the ODE analogs were 231- and 46-fold more active than the unmodified CDV and cCDV. Similar results were obtained using CV. Cytotoxicity studies indicated that although the analogs were more toxic than the parent nucleotides, the selective index was increased by 4- to 13-fold. These results indicate that the alkoxyalkyl esters of CDV and cCDV have enhanced activity in vitro and need to be evaluated for their oral absorption and efficacy in animal models.

Phase II double-blind, placebo-controlled study of the safety and efficacy of cidofovir topical gel for the treatment of patients with human papillomavirus infection

Genital condylomata acuminata are nonmalignant human papillomavirus (HPV)-induced tumors in which HPV types 6 and 11 are most commonly found. Usual treatments for condylomata acuminata are nonspecific and are based on the destruction or removal of infected tissue. These procedures are often painful and are characterized by a high relapse rate. We report here what is to our knowledge the first double-blind, placebo-controlled study of the use of cidofovir, a nucleotide analogue, for the treatment of genital papillomavirus infections. Thirty patients were enrolled in the study; 19 received cidofovir, and 11 received placebo. The median number of warts and the median baseline wart area were comparable for both groups. Nine (47%) of 19 patients in the cidofovir group had a complete response (total healing), compared with 0 of the patients in the placebo group (P=.006). None of the patients in the cidofovir group experienced progression of the disease, compared with 5 (45%) of 11 patients in the placebo group. The side effects recorded for both groups were comparable.

Cytomegalovirus treatment options in immunocompromised patients

Cytomegalovirus (CMV) infection was recognised in congenitally infected infants in the first half of the 20th century. Following the increased use of immunosuppressive regimens for bone marrow and solid organ transplantation, various manifestations of CMV disease were recognised. Milder symptoms included fever, anorexia and malaise but severe symptoms included pneumonitis, hepatitis, gastrointestinal ulceration, choreoretinitis and encephalopathy, all with a high morbidity or mortality. With the onset of the AIDS epidemic, manifestations of CMV became evident, predominantly retinitis. Ganciclovir used intravenously has been the principal anti-CMV agent investigated. However, ganciclovir has problems with suboptimal efficacy, toxicity, poor oral bioavailability and evolution of resistant strains. Additional studies have been performed on foscarnet and cidofovir, although the use of both have been limited by their nephrotoxicity. Combination therapy with ganciclovir and foscarnet for resistant strains has been used. There are promising newer drugs like the methylenecyclopropane nucleoside analogues and benzimidazole. The most novel compound is the antisense oligonucleotide fomivirsen that has been evaluated principally in CMV retinitis. The role of immunotherapy with either immunoglobulin prophylaxis or the novel adoptive immunotherapy needs further evaluation.

A case of human orf in an immunocompromised patient treated successfully with cidofovir cream

Immunocompromised patients may have severe forms of infections. Since there is an increasing number of patients maintained under immunosuppressive therapy, we will be confronted with increasing frequency with these infectious problems. Effective treatments will be of great value. The case is described of a renal transplant with a giant orf lesion, which continued growing instead of regressing spontaneously as is observed usually. The treatment options in such patients are limited. It was decided to treat the patient with the antiviral drug cidofovir (HPMPC, Vistide. Topical cidofovir treatment resulted in complete regression of the lesion. This case is discussed in the context of the known literature on orf (ecthyma contagiosum).