Successful treatment of recurrent vulvar intraepithelial neoplasia resistant to interferon and isotretinoin with cidofovir

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

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

HPV Carcinomas in Immunocompromised Patients

Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide and can result in pre-malignancies or overt malignancies of the skin and mucosal surfaces. HPV-related illnesses are an important personal and public health problem causing physical, mental, sexual and financial detriments. Moreover, this set of malignancies severely affects the immunosuppressed population, particularly HIV-positive patients and organ-transplant recipients. There is growing incidence of HPV-associated anogenital malignancies as well as a decrease in the average age of affected patients, likely related to the rising number of high-risk individuals. Squamous cell carcinoma is the most common type of HPV-related malignancy. Current treatment options for HPV infection and subsequent disease manifestations include imiquimod, retinoids, intralesional bleomycin, and cidofovir; however, primary prevention with HPV vaccination remains the most effective strategy. This review will discuss anogenital lesions in immunocompromised patients, cutaneous warts at nongenital sites, the association of HPV with skin cancer in immunocompromised patients, warts and carcinomas in organ-transplant patients, HIV-positive patients with HPV infections, and the management of cutaneous disease in the immunocompromised patient.

Insights into the mechanism of action of cidofovir and other acyclic nucleoside phosphonates against polyoma- and papillomaviruses and non-viral induced neoplasia

Acyclic nucleoside phosphonates (ANPs) are well-known for their antiviral properties, three of them being approved for the treatment of human immunodeficiency virus infection (tenofovir), chronic hepatitis B (tenofovir and adefovir) or human cytomegalovirus retinitis (cidofovir). In addition, cidofovir is mostly used off-label for the treatment of infections caused by several DNA viruses other than cytomegalovirus, including papilloma- and polyomaviruses, which do not encode their own DNA polymerases. There is considerable interest in understanding why cidofovir is effective against these small DNA tumor viruses. Considering that papilloma- and polyomaviruses cause diseases associated either with productive infection (characterized by high production of infectious virus) or transformation (where only a limited number of viral proteins are expressed without synthesis of viral particles), it can be envisaged that cidofovir may act as antiviral and/or antiproliferative agent. The aim of this review is to discuss the advances in recent years in understanding the mode of action of ANPs as antiproliferative agents, given the fact that current data suggest that their use can be extended to the treatment of non-viral related malignancies.

Reduced tumorigenicity and pathogenicity of cervical carcinoma SiHa cells selected for resistance to cidofovir

Background

Insights into the mechanisms associated with chemotherapy-resistance are important for implementation of therapeutic strategies and for unraveling the mode of action of chemotherapeutics. Although cidofovir (CDV) has proven efficacious in the treatment of human papillomavirus (HPV)-induced proliferation, no studies concerning the development of resistance to CDV in HPV-positive tumor cells have been performed yet.

Methods

From the cervical carcinoma SiHa cells (SiHa_parental), which are HPV-16 positive, cidofovir-resistant cells (SiHa_CDV) were selected, and differential gene expression profiles were analyzed by means of microarrays. We examined in vitro phenotyping of resistant cells compared to parental cells as well as tumorigenicity and pathogenicity in a mouse-xenograft model.

Results

SiHa_CDV had a resistant phenotype and a reduced growth both in vitro and in vivo. A markedly diminished inflammatory response (as measured by production of host- and tumor-derived cytokines and number of neutrophils and macrophages in spleen) was induced by SiHa_CDV than by SiHa_parental in the xenograft model. Gene expression profiling identified several genes with differential expression upon acquisition of CDV-resistance and pointed to a diminished induction of inflammatory response in SiHa_CDV compared to SiHa_parental.

Conclusions

Our results indicate that acquisition of resistance to cidofovir in SiHa cells is linked to reduced pathogenicity. The present study contributes to our understanding on the antiproliferative effects of CDV and on the mechanisms involved, the inflammatory response playing a central role.

Cidofovir selectivity is based on the different response of normal and cancer cells to DNA damage

Background

Cidofovir (CDV) proved efficacious in treatment of human papillomaviruses (HPVs) hyperplasias. Antiproliferative effects of CDV have been associated with apoptosis induction, S-phase accumulation, and increased levels of tumor suppressor proteins. However, the molecular mechanisms for the selectivity and antitumor activity of CDV against HPV-transformed cells remain unexplained.

Methods

We evaluated CDV drug metabolism and incorporation into cellular DNA, in addition to whole genome gene expression profiling by means of microarrays in two HPV⁺ cervical carcinoma cells, HPV^- immortalized keratinocytes, and normal keratinocytes.

Results

Determination of the metabolism and drug incorporation of CDV into genomic DNA demonstrated a higher rate of drug incorporation in HPV⁺ tumor cells and immortalized keratinocytes compared to normal keratinocytes. Gene expression profiling clearly showed distinct and specific drug effects in the cell types investigated. Although an effect on inflammatory response was seen in all cell types, different pathways were identified in normal keratinocytes compared to immortalized keratinocytes and HPV⁺ tumor cells. Notably, Rho GTPase pathways, LXR/RXR pathways, and acute phase response signaling were exclusively activated in immortalized cells. CDV exposed normal keratinocytes displayed activated cell cycle regulation upon DNA damage signaling to allow DNA repair via homologous recombination, resulting in genomic stability and survival. Although CDV induced cell cycle arrest in HPV^- immortalized cells, DNA repair was not activated in these cells. In contrast, HPV⁺ cells lacked cell cycle regulation, leading to genomic instability and eventually apoptosis.

Conclusions

Taken together, our data provide novel insights into the mechanism of action of CDV and its selectivity for HPV-transformed cells. The proposed mechanism suggests that this selectivity is based on the inability of HPV⁺ cells to respond to DNA damage, rather than on a direct anti-HPV effect. Since cell cycle control is deregulated by the viral oncoproteins E6 and E7 in HPV⁺ cells, these cells are more susceptible to DNA damage than normal keratinocytes. Our findings underline the therapeutic potential of CDV for HPV-associated malignancies as well as other neoplasias.

Human papillomavirus-related genital disease in the immunocompromised host: Part II

Human papillomavirus is responsible for common condyloma acuminata and a number of premalignant and malignant anogenital lesions. The immunocompromised population is at particular risk because of a higher incidence of malignant transformation. Lesions in this population may prove refractory to standard treatment. This is part II of a two-part review that will discuss the treatment of condyloma acuminata and vaginal, vulvar, penile, and anal intraepithelial neoplasias. This article will provide an updated review of available treatments, with a focus on recent advances and the challenges faced in successfully treating human papillomavirus lesions in the immunocompromised host.

Cidofovir: clinical experience and future perspectives on an acyclic nucleoside phosphonate analog of cytosine in the treatment of refractory and premalignant HPV-associated anal lesions

BACKGROUND

Cidofovir, a nucleotide analog with antiviral activity against a broad range of DNA viruses including human papilloma viruses (HPV), is available off label to clinicians.

OBJECTIVE

To provide a better knowledge of pharmacology and effects when topically applied.

METHODS

After reviewing the chemistry, physiology, and animal studies, an overview of clinical studies is provided.

RESULTS/CONCLUSIONS

Cidofovir, as a result of its antiviral and antiproliferative activity and its ability to induce apoptosis, can offer a solution for the treatment of severe recurrent HPV-induced lesions. It can also be used to attempt to treat dysplastic lesions and as an adjuvant treatment. The long-lasting antiviral activity allows infrequent dosing. As a rule, cidofovir applied on the skin is well tolerated, even in long-term treatment. The dose-limiting nephrotoxicity of the drug is not a concern in patients with a glomerular filtration rate within the normal range. Cidofovir has clearly influenced the landscape of refractory and dysplastic anogenital condylomata acuminata and its use has increased over the last decade. However, further controlled clinical trials are needed to assess the role of cidofovir and its derivatives.

Local administration of cidofovir for human papilloma virus associated skin lesions in transplant recipients

Human papilloma virus (HPV)-associated diseases are increasingly diagnosed in solid organ recipients. Cidofovir (CDV) is a broad-spectrum antiviral agent with activity against all human herpes viruses and HPV. From 2000-2004, a total of 1303 solid organ transplants (SOT) were performed at our center. Six transplant recipients were treated with topical CDV for HPV-associated lesions. One cardiac recipient responded to a single injection of CDV into his recurrent anal condylomata. In a renal recipient with recurrent penile condylomata CDV was injected into the lesions four times (2 week interval) until lesions regressed. One renal recipient developed multiple vaginal and anal intradermal neoplasias, which relapsed after laser ablation. The lesions were repeatedly injected with CDV and completely disappeared. Two renal recipients with widespread verrucae vulgares were treated with CDV gel, which resulted in regression of the lesions. One patient developed donor derived verrucae vulgares on both transplanted hands, which responded to CDV gel. Four of the six patients were switched from calcineurin inhibitors (CNIs) to Sirolimus (SIR). CDV was found effective in the treatment of HPV-associated skin lesions in SOT recipients. It needs to be determined whether switch from CNIs to SIR might have contributed to the beneficial effect of CDV.

Medical management of vulvar intraepithelial neoplasia

OBJECTIVE

To determine which nonsurgical treatments have been assessed for the treatment of vulvar intraepithelial neoplasia (VIN) and what the outcomes of such treatment might be.

MATERIALS AND METHODS

The English literature over the last 25 years was searched on Medline.

RESULTS

A wide variety of nonsurgical treatments was identified and the outcomes were very similar. These treatments showed responses rates varying between 10% and 60%. Responses were poorly defined, however, and few if any studies had large enough subject numbers or long enough follow-up to allow robust conclusions.

CONCLUSIONS

Although VIN is a condition in which there would seem to be a pressing need for nonsurgical interventions, none of the nonsurgical treatments reviewed resulted in optimal outcomes. No one treatment seemed to be superior. There is a need for consensus on how outcomes are measured and a move toward large well-constructed studies is recommended. Because VIN is uncommon, there is a strong case for establishing research collaboratives.

Acute infections as a means of cancer prevention: opposing effects to chronic infections?

PURPOSE

Epidemiological studies have found an inverse association between acute infections and cancer development. In this paper, we review the evidence examining this potentially antagonistic relationship.

METHODS

In addition to a review of the historical literature, we examined the recent epidemiological evidence on the relationship between acute infections and subsequent cancer development in adult life. We also discuss the impact of chronic infections on tumor development and the influence of the immune system in this process.

RESULTS

Exposures to febrile infectious childhood diseases were associated with subsequently reduced risks for melanoma, ovary, and multiple cancers combined, significant in the latter two groups. Epidemiological studies on common acute infections in adults and subsequent cancer development found these infections to be associated with reduced risks for meningioma, glioma, melanoma and multiple cancers combined, significantly for the latter three groups. Overall, risk reduction increased with the frequency of infections, with febrile infections affording the greatest protection. In contrast to acute infections, chronic infections can be viewed as resulting from a failed immune response and an increasing number have been associated with an elevated cancer risk.

CONCLUSION

Infections may play a paradoxical role in cancer development with chronic infections often being tumorigenic and acute infections being antagonistic to cancer.

Therapy for genital human papillomavirus-related disease

Genital human papillomavirus (HPV) infection is very common, and often sub-clinical and usually resolves without any treatment. Genital warts are caused by HPV 6/11 infection and are one of the commonest clinically recognised disease manifestations of genital HPV. Subjects with genital warts usually perceive them as cosmetically disfiguring, often leading to adverse psychological symptoms, and most subjects with genital warts will present requesting treatment. A wide variety of treatments are available including both provider- and patient-applied therapies. Various individual subject and disease factors mediate appropriate therapy choice. Some of the treatments that are used for genital warts can also be used for some cases of intraepithelial neoplasia caused by high-oncogenic risk HPVs occurring at vulval, anal or penile sites. Specific treatment considerations apply to genital warts in pregnancy and laryngeal papillomatosis and these are also discussed.

Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections: cidofovir against herpesvirus (herpes simplex virus types 1 and 2 varicella-zoster virus, cytomegalovirus [CMV], Epstein-Barr virus, and human herpesviruses 6, 7, and 8), polyomavirus, papillomavirus, adenovirus, and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus, and orf virus) infections; adefovir against herpesvirus, hepadnavirus (human hepatitis B virus), and retrovirus (human immunodeficiency virus types 1 [HIV-1] and 2 [HIV-2], simian immunodeficiency virus, and feline immunodeficiency virus) infections; and tenofovir against both hepadnavirus and retrovirus infections. Cidofovir (Vistide) has been officially approved for the treatment of CMV retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) has been approved for the treatment of HIV infections (i.e., AIDS), and adefovir dipivoxil (Hepsera) has been approved for the treatment of chronic hepatitis B. Nephrotoxicity is the dose-limiting side effect for cidofovir (Vistide) when used intravenously (5 mg/kg); no toxic side effects have been described for adefovir dipivoxil and tenofovir disoproxil fumarate, at the approved doses (Hepsera at 10 mg orally daily and Viread at 300 mg orally daily).

Topical cidofovir for the treatment of dermatologic conditions: verruca, condyloma, intraepithelial neoplasia, herpes simplex and its potential use in smallpox

Cidofovir is a new antiviral drug that has a broad spectrum of activity against several DNA viruses. Many of the disorders caused by these viruses do not have satisfactory therapy, and given the efficacy of this agent in treating many of these conditions, it holds great promise. It is hoped that ongoing studies will confirm the initial anecdotal reports regarding its therapeutic efficacy and lack of systemic side effects. It is also hoped that the cost to formulate and use cidofovir topically will eventually decrease to a level that will allow more widespread use of this drug.

Epidemiology, diagnosis and treatment of vulvar intraepithelial neoplasia

The incidence of human papilloma virus-related vulvar intraepithelial neoplasia is increasing worldwide. This is associated with an increasing incidence of invasive vulvar cancer in young women. Undifferentiated vulvar intraepithelial neoplasia has an invasive potential; a subset of very young patients with pigmented lesions and spontaneous regression has been described. Differentiated vulvar intraepithelial neoplasia is human papilloma virus negative and affects older women, who are at risk of invasive cancer. Chromosomal changes and angiogenesis may play a role in carcinogenesis. Immunocompromised women bear a substantial risk of vulvar intraepithelial neoplasia. These facts demand the awareness of both women and physicians, because there is evidence of diagnostic delays in patients with vulvar cancer. The standard treatment is surgical excision, which may be combined with laser treatment in extensive disease. Preliminary results of topical antiviral agents and photodynamic therapy are available, but remain to be confirmed by prospective, placebo-controlled studies.