Therapeutic developments in cytomegalovirus retinitis

Prevention of herpes simplex virus induced stromal keratitis by a glycoprotein B-specific monoclonal antibody

The increasing incidence of acyclovir (ACV) and multidrug-resistant strains in patients with corneal HSV-1 infections leading to Herpetic Stromal Keratitis (HSK) is a major health problem in industrialized countries and often results in blindness. To overcome this obstacle, we have previously developed an HSV-gB-specific monoclonal antibody (mAb 2c) that proved to be highly protective in immunodeficient NOD/SCID-mice towards genital infections. In the present study, we examined the effectivity of mAb 2c in preventing the immunopathological disease HSK in the HSK BALB/c mouse model. Therefore, mice were inoculated with HSV-1 strain KOS on the scarified cornea to induce HSK and subsequently either systemically or topically treated with mAb 2c. Systemic treatment was performed by intravenous administration of mAb 2c 24 h prior to infection (pre-exposure prophylaxis) or 24, 40, and 56 hours after infection (post-exposure immunotherapy). Topical treatment was performed by periodical inoculations (5 times per day) of antibody-containing eye drops as control, starting at 24 h post infection. Systemic antibody treatment markedly reduced viral loads at the site of infection and completely protected mice from developing HSK. The administration of the antiviral antibody prior or post infection was equally effective. Topical treatment had no improving effect on the severity of HSK. In conclusion, our data demonstrate that mAb 2c proved to be an excellent drug for the treatment of corneal HSV-infections and for prevention of HSK and blindness. Moreover, the humanized counterpart (mAb hu2c) was equally effective in protecting mice from HSV-induced HSK when compared to the parental mouse antibody. These results warrant the future development of this antibody as a novel approach for the treatment of corneal HSV-infections in humans.

Side-effects of cidofovir in the treatment of recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) is a chronic and difficult to treat disease of the larynx. In 1998, the first article was published that described the use of the antiviral substance cidofovir to treat this disease. Although the results are promising, there remains some concern about the potential carcinogenicity of cidofovir. There is a demand for a qualitative review of the side-effects of this medicine. In this review, the side-effects of cidofovir are investigated. Special attention was given to the potential carcinogenicity of cidofovir. For this review a search is performed in PubMed and EMBASE for relevant articles in which the use of intralesional cidofovir for patients with RRP is described. Eventually, 31 articles could be included for this review. In these articles a total of 188 patients with RRP were described who underwent therapy with intralesional cidofovir. Five of these patients have developed dysplasia of the larynx during the treatment with cidofovir. This is a percentage of 2.7. This percentage is concurrent with the incidence of spontaneous malignant degeneration of RRP (2–3%). Based on this review, it can be concluded that the use of intralesional cidofovir does not increase the risk of laryngeal dysplasia. Apart from the articles that describe the intralesional administration of cidofovir, some articles have been published in which the use of intravenous cidofovir is described as a therapy for RRP. Therefore, a summary is given on the side-effects of intralesional cidofovir as well as a summary on the reported side-effects of the intravenous administration of cidofovir. Based on the outcomes of this review, recommendations are given for a safe use of cidofovir for treatment of recurrent respiratory papillomatosis in the future.

7-Oxo-4,7-dihydrothieno[3,2-b]pyridine-6-carboxamides: Synthesis and biological activity of a new class of highly potent inhibitors of human cytomegalovirus DNA polymerase

We report a new class of non-nucleoside antivirals, the 7-oxo-4,7-dihydrothieno[3,2-b]pyridine-6-carboxamides, some of which possess remarkable potency versus a broad spectrum of herpesvirus DNA polymerases and excellent selectivity compared to human DNA polymerases. A critical factor in the level of activity is hypothesized to be conformational restriction of the key 2-aryl-2-hydroxyethylamine sidechain by an adjacent methyl group.

Pyrimidine Acyclic Nucleotide Analogues with Aromatic Substituents in C-5 Position

NH2-protected 5-phenylcytosine and its derivatives 2a-2d were treated with (2S)-2-[(trityloxy)methyl]oxirane (3) followed by etherification with diisopropyl [(tosyloxy)methyl]phosphonate (5) in the presence of sodium hydride. The intermediary phosphonate esters 6 were debenzoylated and subsequently transformed to free phosphonic acids, i.e. (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-phenylcytosine (5-phenyl-HPMPC) derivatives (8a-8d) by the action of bromotrimethylsilane and subsequent hydrolysis. Deamination of these compounds with 3-methylbutyl nitrite afforded corresponding (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-phenyluracil (5-phenyl-HPMPU) derivatives (9a-9d). R-Enantiomers 14 and 15 were prepared analogously starting from (2R)-2-[(trityloxy)methyl]oxirane. 5-Benzyl-, 5-[(1-naphthyl)methyl]- and 5-[(2-naphthyl)methyl]HPMPU (24a-24c) and -HPMPC (25a-25c) were synthesized from appropriate 5-arylmethyl-4-methoxypyrimidin-2(1H)-ones similarly as described for 5-phenyl derivatives. Antiviral activity was found for (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-phenyluracil (9a) (HSV-1 and HSV-2) and (R)-1-[3-hydroxy2-(phosphonomethoxy)propyl]-5-phenylcytosine (14) (cytomegalovirus and varicella-zoster virus), both tested in cell cultures. Some of the 5-phenyluracil derivatives possessed inhibitory activity against thymidine phosphorylase from SD-lymphoma.

Inhibition of herpesvirus replication by a series of 4-oxo-dihydroquinolines with viral polymerase activity

Herpesviruses cause a wide variety of human diseases ranging from cold sores and genital herpes to encephalitis, congenital infections and lymphoproliferative diseases. These opportunistic viruses cause major problems in immunocompromised individuals such as transplant recipients, cancer patients, and HIV-infected persons. The current treatment of these infections is not optimal and there is a need for more active, less toxic compounds that might be used in place of or in addition to current therapies. We have evaluated a new series of 4-oxo-dihydroquinolines, which have a different mechanism of action than nucleosides and have activity against multiple herpesviruses. Of the four new compounds evaluated, two (PHA-529311 and PHA-570886) had greater activity than the parent, PHA-183792, against several herpesviruses and one (PHA-568561) was as effective as the parent. A fourth, PHA-243672, was considerably less effective. They had greater efficacy against cytomegalovirus (CMV) than the other herpesviruses tested and also had activity against acyclovir-resistant herpes simplex virus and varicella-zoster virus isolates and ganciclovir or foscarnet-resistant CMV isolates. These results confirm the broad-spectrum efficacy of these compounds against multiple herpesviruses and suggest that members of this class may have a potential role for treatment of a variety of herpesvirus infections.

Intralesional cidofovir and surgical excision for laryngeal papillomatosis

OBJECTIVE

To evaluate the efficacy of cidofovir intralesional therapy in recurrent respiratory papillomatosis and the role of surgical excision as an associated treatment.

STUDY DESIGN

Prospective study and case series.

METHOD

Twenty-six patients received intralesional cidofovir. Three endoscopies were performed at monthly intervals, with intralesion injections of cidofovir at 5 mg/mL. Further endoscopic evaluation was made at 3 or 6 months depending on whether there was persistent papillomatosis. Cidofovir was again injected in the case of persistent papillomas, and treatment was repeated as long as papillomas were observed. Surgical excision of the papilloma was only performed in cases of airway obstruction or in cases proving resistant to cidofovir.

RESULTS

Complete remission was obtained in 8 (31%) patients after an average of 2.6 endoscopic treatment. Seventeen (65%) patients presented slight or mild disease at endpoint (final severity score 1-4). Significant results were obtained in both adults and children. A greater response was obtained in the supraglottis and glottis subsites than in subglottis, tracheal, and other sites. Patients conforming to the 1 month interinjection schedule showed better responses in supraglottis subsite than those receiving their injections with intervals longer than 1 month. Combined therapy (cidofovir plus excision) was necessary in persistent papillomas. No patients presented with any systemic or local side effects.

CONCLUSIONS

Cidofovir therapy was an effective treatment in adults and in children, allowing papillomatosis to be controlled without observed side effects. Surgical excision associated with cidofovir injections remained necessary in persistent papillomatosis after cidofovir treatment.

Potential antiviral therapeutics for smallpox, monkeypox and other orthopoxvirus infections

We assessed the activities of 24 different antiviral compounds against smallpox (two strains of variola major and one of variola minor), monkeypox, vaccinia and cowpox viruses by a neutral red uptake assay. To establish assay parameters, we examined viral replication and its inhibition at various times postinfection and at several multiplicities of infection. Drugs were selected to target a range of functions involved in viral replication. Eight compounds (cidofovir, cyclic HPMPC (cHPMPC), HPMPA, ribavirin, tiazofurin, carbocyclic 3-deazaadenosine, 3-deazaneplanocin A and DFBA (1-(2,4-difluorobenzyloxy)adenosine perchlorate)-a derivative of adenosine N1-oxide) inhibited the replication of all three variola strains and the other orthopoxviruses at drug concentrations within a pharmacologically achievable range. Two others (methisazone and bis-POM-PMEA) showed a lesser degree of antiviral effect, while the remainder were inactive. To examine possible naturally occurring drug resistance among a large number of variola isolates obtained from different geographical regions and at different times, we examined the sensitivity of 35 different strains of variola as well as other orthopoxviruses to a subset of three of the most active compounds: cidofovir, cHPMPC, and ribavirin. Preliminary data indicate that nearly all isolates appear to have similar drug sensitivities. These findings are currently being verified and expanded.

Intralesional cidofovir therapy for laryngeal papilloma in an adult cohort

OBJECTIVES

To confirm the safety and efficacy of intralesional cidofovir in the management of laryngeal papilloma and to identify variables that correlate with number of injections needed to achieve remission.

STUDY DESIGN

An open-trial prospective evaluation of the efficacy of intralesional cidofovir in subjects with laryngeal papilloma.

METHODS

Fourteen adult subjects with biopsy-proven laryngeal papilloma were enrolled in a treatment study of intralesional cidofovir. Preprotocol disease duration ranged from 1 to 30 years with a mean duration of 7 years. Subjects received monthly injections of cidofovir with a maximum dose of 37.5 mg per injection in 6 cc saline (6.25 mg/mL). Injections were repeated until no papilloma could be visually identified during an intraoperative evaluation. After disease remission was achieved, subjects received an additional injection. All injections occurred during suspension microlaryngoscopy.

RESULTS

All subjects have achieved disease remission using an injection-only treatment protocol. No additional laryngeal scarring or systemic toxicity was identified. On average, 6 injections were required to achieve remission. Preprotocol disease duration and anatomical staging correlated positively with the number of injections required for disease remission.

CONCLUSIONS

Intralesional injection of cidofovir is an excellent treatment option with limited local and systemic toxicities. The injection therapy regimen requires perseverance from both patient and surgeon. Remission of disease can be achieved in adults with laryngeal papilloma.

Oral valganciclovir: a new option for treatment of cytomegalovirus infection and disease in immunocompromised hosts

Immunocompromised hosts are at increased risk of cytomegalovirus (CMV) infection and serious CMV disease. CMV infection is an important cause of morbidity among patients infected with HIV and after solid organ transplantation (SOT) and may cause life-threatening disease in allogeneic stem cell transplant (SCT) recipients. The introduction into clinical use of potent antiviral compounds and of rapid detection assays for CMV during the past two decades has allowed development of strategies for the prevention and treatment of disease caused by CMV in these groups of immunocompromised patients. At present, the antiviral drugs ganciclovir, foscarnet and cidofovir are commonly used in the treatment of CMV infection and disease. However, these agents have a poor oral bioavailability and, for systemic use, require iv. administration for most indications. Valganciclovir is an oral prodrug of ganciclovir, with a 10-fold greater bioavailability than oral ganciclovir. Studies of the pharmacokinetics of valganciclovir among HIV-infected CMV-seropositive patients and liver transplant recipients suggest that this oral compound has the potential to replace both oral and iv. ganciclovir in many situations if it is shown to be as efficacious and safe as those ganciclovir formulations in immunodeficient patients. In the first part of this review, currently established approaches to the management of CMV infection and disease in SCT and SOT recipients and HIV-infected patients are discussed to highlight possible indications for future valganciclovir use; in the second part, data from human studies of valganciclovir are presented.

Naphthalene carboxamides as inhibitors of human cytomegalovirus DNA polymerase

ortho-Hydroxynaphthalene carboxamides have been identified as inhibitors of HCMV DNA polymerase. SAR investigations have demonstrated that both the amide and hydroxy functionalities are required for activity. Substitution on the naphthalene ring has led to inhibitors with submicromolar IC50s against HCMV polymerase. These compounds have been found to be >100-fold selective for inhibition of HCMV polymerase versus human alpha polymerase and display antiviral activity in a cell-based plaque reduction assay.