Safety and efficacy of topical cidofovir to treat high-grade perianal and vulvar intraepithelial neoplasia in HIV-positive men and women

Condyloma and Anal Dysplasia

Anal intraepithelial neoplasia (AIN) are precancerous lesions and are sequela of human papilloma virus (HPV) infection. AIN is classified as low-grade squamous intraepithelial lesion or high-grade squamous intraepithelial lesion. Screening with anal cytology and anoscopy should be considered for high-risk populations. Diagnosis is made through high resolution anaoscopy and biopsy. Options for treatment include ablation and several topical therapies; however, recurrence rates are high for all treatment options, and an ongoing surveillance is necessary to prevent progression to anal squamous cell carcinoma. HPV vaccination is recommended to prevent disease.

Safety and efficacy of topical artesunate for the treatment of vulvar intraepithelial neoplasia 2/3

OBJECTIVE

To evaluate the safety, tolerability, and efficacy of topical artesunate ointment for treatment of biopsy-confirmed Human papillomavirus (HPV)-associated Vulvar intraepithelial neoplasia (VIN) 2/3.

METHODS

Participants were enrolled on a prospective, IRB-approved, dose-escalation phase I trial testing either 1, 2 or 3 treatment cycles (5 days), every other week, as applicable. Clinical assessments were completed prior to each dose cycle and included exam and review of adverse event (AE) diary cards. HPV testing and colposcopy was completed at 15 and 28 weeks. AEs were assessed according to CTCAE 4.0 criteria. Complete responders (CR) underwent biopsy of the treated site at the 28-weeks while partial (PR) and non (NR)-responders underwent surgical resection or biopsy and ablation.

RESULTS

Fifteen patients consented to and began treatment. Per-protocol assessments were completed in 100% at 15- and 80% at 28-weeks. All patients completed prescribed cycles with no grade 3 or 4 AEs. Vulvovaginal burning/ was the most common AE occurring in 93.3%. AEs were grade 2 in 23.7% and included vulvovaginal pruritus (n = 3), swelling (n = 3) and candidiasis (n = 2). The highest ORR was in the 3-cycle group (88.9% with 55.6% CR). HPV-16 was detected either alone (46.7%) or with other subtypes (33.3%) in 80% of lesions and 5 of 8 (62.5%) with CR had complete viral clearance.

CONCLUSIONS

Topical artesunate for treatment of high-grade VIN shows high tolerability, low toxicity and evidence for clinical response in this initial small series. The safety and observed responses support further study in a Phase II trial.

Identification and confirmation via in situ hybridization of Merkel cell polyomavirus in rare cases of posttransplant cutaneous T-cell lymphoma

BACKGROUND

Viral infection is an oncogenic factor in many hematolymphoid malignancies. We sought to determine the diagnostic yield of aligning off-target reads incidentally obtained during targeted hematolymphoid next-generation sequencing to a large database of viral genomes to screen for viral sequences within tumor specimens.

METHODS

Alignment of off-target reads to viral genomes was performed using magicBLAST. Localization of Merkel cell polyomavirus (MCPyV) RNA was confirmed by RNAScope in situ hybridization. Integration analysis was performed using Virus-Clip.

RESULTS

Four cases of post-cardiac-transplant folliculotropic mycosis fungoides (fMF) and one case of peripheral T-cell lymphoma (PTCL) were positive in off-target reads for MCPyV DNA. Two of the four cases of posttransplant fMF and the case of PTCL showed localization of MCPyV RNA to malignant lymphocytes, whereas the remaining two cases of posttransplant fMF showed MCPyV RNA in keratinocytes.

CONCLUSIONS

Our findings raise the question of whether MCPyV may play a role in rare cases of T-lymphoproliferative disorders, particularly in the skin and in the heavily immunosuppressed posttransplant setting.

Effectiveness of topical cidofovir for treatment of refractory anal high-grade squamous intraepithelial lesion

OBJECTIVES

Ablative electrocautery is effective treating anal high-grade squamous intraepithelial lesions (HSILs). However, persistence or recurrence of the HSIL despite ablative sessions is not uncommon. The aim of this study is to assess the feasibility of topical cidofovir as salvage therapy for the management of refractory HSIL.

DESIGN

A prospective uncontrolled unicenter study of men and transgender people who have sex with men with HIV who had a refractory intra-anal HSIL after ablative treatments and who received topical cidofovir (ointment at 1%, auto-applicated, three times a week, a total of 8 weeks) as salvage therapy. Effectiveness was evaluated on-treatment defining response as resolution or regression to low-grade lesion of HSIL in the biopsy posttreatment. Tolerance and recurrences were recorded.

RESULTS

From 2017 to 2022, 23 patients with refractory intra-anal HSIL (78.3% persistent lesions, 39% affecting > 50% of circumference, and a median of six previous ablative sessions) were treated with topical cidofovir. A response was observed in 16 of 23 patients [69.5% (95% confidence interval (95% CI) 50.8-88.4)]. Local tolerance was reported as regular or bad in 13 patients (52.2%), requiring modification of the treatment in eight patients (three early discontinuation and five dose reduction). Non-serious side effects were reported. After a median follow-up of 30.3 months, two of the 16 patients with a response developed recurrent HSIL [recurrence rate, 25.4% at 12 months (95% CI, 0-35)].

CONCLUSION

Topical cidofovir could be a good option in the management of anal HSIL due to its good effectiveness, low recurrence rate, and acceptable tolerance even in difficult-to-treat lesions.

Anal Cancer and Anal Intraepithelial Neoplasia Risk among Patients Treated for HPV-Related Gynecological Diseases-A Systematic Review

BACKGROUND

The most important causative agent of neoplasms in the anogenital area is the human papillomavirus (HPV). Due to the anatomical proximity of the genital and anus area and the ease with which HPV infection is transmitted, it seems that patients after the treatment of HPV-related gynecological diseases may have an increased risk of developing a second HPV-related neoplasm anal cancer. The aim of this study was to determine the risk of anal intraepithelial neoplasia (AIN) and anal cancer (AC) among patients after the treatment of HPV-related gynecological diseases.

METHODS

We conducted a comprehensive review of the available literature from multiple databases. The study was performed following Cochrane Reviewers' Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2009 guidelines. Moreover, we assessed the quality of each study using QUADAS-2.

RESULTS

Twenty-five studies were included in the final analysis. Patients after the treatment of HPV-related gynecological diseases have a significantly higher risk of AC (mean standardized incidence ratio (SIR) = 5.387, mean incidence risk (IR) = 0.096%, mean IR per 100,000 person-years = 10.37) and AIN (mean IR = 23.683%) compared to the population risk.

CONCLUSIONS

patients with HPV-related gynecological diseases should constitute a group for which an appropriate primary and secondary screening for AC should be introduced.

Anal Intraepithelial Neoplasia: Precursor of Anal Squamous Cell Carcinoma

Anal squamous cell carcinoma (SCC) is rare, but it has been commonly detected as an invasive cancer. The standard treatment for anal SCC was surgical resection. However, recent medical advances have enabled the standard treatment to be chemoradiotherapy. Anal intraepithelial neoplasia (AIN) is a premalignant lesion of SCC. The screening test for AIN and human papilloma virus vaccine are important for the following high-risk patients: patients positive for human immunodeficiency virus and men who have sexual intercourse with men. Although cytology can be easily applied for a screening test, the false-negative rate for AIN is high. Instead, high-resolution anoscopy (HRA) has been gaining attention as a promising screening method for high-risk patients. Investigations comparing characteristic findings of HRA with the histology of AIN have demonstrated that HRA is a highly specific test for AIN. Magnifying or image-enhanced endoscopies are also routinely used for colonoscopy, as they allow detailed observations at higher magnifications than those of HRA. Hence, these endoscopic modalities can be applied for assessing AIN. Ablation therapies or topical medications are available as the local treatment for AIN. Although endoscopic submucosal dissection is considered to be feasible to remove AIN, it has a technical difficulty to approach endoscopically invisible areas. Hence, this technique may be useful to resect AIN localized in the endoscopically visible areas, when the localization is confirmed via targeted biopsy.

Evaluating the efficacy of treatment options for anal intraepithelial neoplasia: a systematic review

PURPOSE

Anal intraepithelial neoplasia (AIN) is the accepted precursor of anal squamous cell carcinoma (ASCC). There has long been a hypothesis that treating AIN may prevent ASCC. Many different treatment modalities have been suggested and studied. We conducted this systematic review to evaluate their efficacy and the evidence as to whether we can prevent ASCC by treating AIN.

METHODS

MEDLINE and EMBASE were electronically searched using relevant search terms. All studies investigating the use of a single treatment for AIN that reported at least one end outcome such as partial or complete response to treatment, recurrence after treatment and/or ASCC diagnosis after treatment were included.

RESULTS

Thirty studies were included in the systematic review investigating 10 treatment modalities: 5% imiquimod, 5-fluorouracil, cidofovir, trichloroacetic acid, electrocautery, surgical excision, infrared coagulation, radiofrequency ablation, photodynamic therapy and HPV vaccination. All treatment modalities demonstrated some initial regression of AIN after treatment; however, recurrence rates were high especially in HIV-positive patients. Many of the studies suffered from significant bias which prevented direct comparison.

CONCLUSIONS

Although the theory persists that by inducing the regression of AIN, we may be able to reduce the risk of ASCC, there was no clinical evidence within the literature advocating that treating AIN does prevent ASCC.

Refractory extensive vulvar high-grade squamous intraepithelial lesion in an immunosuppressed transplant patient treated with topical cidofovir: A case report

High-grade squamous intraepithelial lesion of the vulva is a premalignant condition which may be especially resistant to treatments among immunosuppressed patients. We present our experience with the use of topical cidofovir in a refractory case of extensive vulvar high-grade squamous intraepithelial lesion in a 37-year-old transplant patient. Eighteen cycles of cidofovir over a 2-year period led to a sustained significant improvement, mainly of the mucosal lesions and was well tolerated. To our knowledge, we have not seen this therapy described in transplant patients with extensive high-grade squamous intraepithelial lesion.

Successful treatment of genital warts with cidofovir cream in a pediatric patient with Fanconi anemia

INTRODUCTION

Patients with Fanconi anemia have an increased susceptibility to malignancies associated with human papillomavirus, and thus prevention and early management of human papillomavirus infections in this patient population are crucial.

CASE REPORT

A nine-year-old girl with Fanconi anemia developed genital warts about three years after undergoing haplo-identical stem cell transplant. The transplant was complicated by chronic graft-versus-host disease, and the patient had therefore received multiple immunosuppressants. The genital warts were treated with several creams, but minimal improvement was reported.

MANAGEMENT AND OUTCOME

Cidofovir was extemporaneously compounded into an unscented 1% moisturizing cream and applied daily at bedtime to the genital warts. By the end of treatment, the warts had been successfully treated, and no adverse events were reported. The patient is still free of any lesions at six months after completing treatment.

DISCUSSION

Although reports have been published on the use of cidofovir cream, most were in adults with non-genital warts. Cidofovir cream may be considered as a treatment option for refractory genital warts in pediatric patients. However, further studies are needed to better define the optimal preparation and dosing for such patient population.

Human Papilloma Virus Infection and Anal Squamous Intraepithelial Lesions

This article addresses the natural history of the human papilloma virus (HPV) infection to anal squamous intraepithelial lesions, and onto squamous cell carcinoma of the anus. This article provides overviews of the virology, pathophysiology, nomenclature, classification, historical terms, risk factors, clinical evaluation, differential diagnosis, and treatment of HPV infection and its sequelae.

Tenofovir disoproxil fumarate intravaginal ring for HIV pre-exposure prophylaxis in sexually active women: a phase 1, single-blind, randomised, controlled trial

BACKGROUND

An intravaginal ring that releases the tenofovir prodrug, tenofovir disoproxil fumarate, provided 100% protection in macaques against simian HIV and was safe in a 14-day clinical trial in sexually abstinent women. We aimed to assess the safety and pharmacokinetics of this intravaginal ring over 90 days in sexually active women.

METHODS

We did a phase 1, single-blind, randomised, placebo-controlled trial to assess safety, pharmacokinetics, and acceptability of a tenofovir disoproxil fumarate intravaginal ring used continuously with monthly ring changes for 3 months. Sexually active women who were HIV negative were randomly assigned (3:1) to a tenofovir disoproxil fumarate ring or placebo ring. Primary safety endpoint was the proportion of women who had grade 2 or higher genitourinary adverse events judged related to study product and any grade 2 or higher adverse event as defined by the Division of AIDS Table for Grading the Severity of Adult and Pediatric Adverse Events. We quantified tenofovir disoproxil fumarate and tenofovir concentrations in cervicovaginal fluid, tenofovir in plasma, and tenofovir diphosphate, the active metabolite, in cervical tissue and dried blood spots 1 month after each ring insertion. We compared changes over time in cervicovaginal fluid cytokine and chemokine concentrations and vaginal microbiota. The study was electively stopped early and is registered with ClinicalTrials.gov, number NCT02762617.

FINDINGS

Between Feb 24 and July 20, 2017, 17 women were enrolled before study termination. 12 were assigned to receive the tenofovir disoproxil fumarate ring and five were assigned to receive the placebo ring. Two participants in the tenofovir disoproxil fumarate ring group completed 3 months of continuous ring use; eight were asked to discontinue ring use early because of ulcerations (grade 1) near the ring; in the remaining two women, rings were electively removed by study staff on day 20 and day 23. Ulcers were detected a mean of 32 days after ring use (range 23-56). Four of eight participants with ulcers were symptomatic with vaginal discharge; four had ulcers identified when examined; three had two ulcers; all ulcers resolved after ring removal. No participants in the placebo group developed ulcers. No grade 2 product-related adverse events were reported in either group and four non-product-related grade 2 adverse events were reported in the tenofovir disoproxil fumarate ring group. Cervicovaginal fluid tenofovir concentrations did not differ at day 14 (p=0·14) comparing the eight patients who did (median 1·0 × 105 ng/mL [IQR 9·1 × 104-1·1 × 105]) with the four who did not (6·0 × 104 ng/mL [5·6 × 104-1·1 × 105]) develop ulcers. No significant changes in vaginal microbiota were detected in either group. Concentrations of multiple inflammatory cytokines and chemokines were significantly higher at days 14 and 28 compared with baseline in the tenofovir disoproxil fumarate ring group but not the placebo group.

INTERPRETATION

Future studies are needed to establish whether the unanticipated finding of ulcerations is specific to this tenofovir disoproxil fumarate ring or generalisable to other sustained topical release formulations of tenofovir or its prodrugs.

FUNDING

National Institutes of Health.

Current strategies against persistent human papillomavirus infection (Review)

Human papillomavirus (HPV) is the most common sexually transmitted infection, exhibiting a tropism for the epidermis and mucosae. The link between persistent HPV infection and malignancies involving the anogenital tract as well as the head and neck has been well‑established, and it is estimated that HPV‑related cancers involving various anatomical sites account for 4.5% of all human cancers. Current prophylactic vaccines against HPV have enabled the prevention of associated malignancies. However, the sizeable population base of current infection in whom prophylactic vaccines are not applicable, certain high‑risk HPV types not included in vaccines, and the vast susceptible population in developing countries who do not have access to the costly prophylactic vaccines, put forward an imperative need for effective therapies targeting persistent infection. In this article, the life cycle of HPV, the mechanisms facilitating HPV evasion of recognition and clearance by the host immune system, and the promising therapeutic strategies currently under investigation, particularly antiviral drugs and therapeutic vaccines, are reviewed.

Practice parameters for the diagnosis and treatment of anal intraepithelial neoplasia (AIN) on behalf of the Italian Society of Colorectal Surgery (SICCR)

Squamous cell carcinoma (SCC) of the anus is a human papilloma virus (HPV) related malignancy that is preceded by anal intraepithelial neoplasia (AIN) making this cancer, at least theoretically, a preventable disease. In the past 10 years the diagnosis, management and nomenclature of AIN has dramatically changed. Increased life expectancy in human immunodeficiency virus (HIV) positive patients due to highly active antiretroviral therapy (HAART) has caused an increase in the incidence of SCC of the anus. While many experts recommend screening and treatment of anal high-grade squamous intraepithelial lesion (HSIL), there is no consensus on the optimal management these lesions. Therefore, there is a need to review the current evidence on diagnosis and treatment of AIN and formulate recommendations to guide management. Surgeons who are members of the Italian Society of Colorectal Surgery (SICCR) with a recognized interest in AIN were invited to contribute on various topics after a comprehensive literature search. Levels of evidence were classified using the Oxford Centre for Evidence-based Medicine of 2009 and the strength of recommendation was graded according to the United States (US) preventive services task force. These recommendations are among the few entirely dedicated only to the precursors of SCC of the anus and provide an evidence-based summary of the current knowledge about the management of AIN that will serve as a reference for clinicians involved in the treatment of patients at risk for anal cancer.

In vitro comparison of currently available and investigational antiviral agents against pathogenic human double-stranded DNA viruses: A systematic literature review

BACKGROUND

Double-stranded (ds) DNA virus infections often occur concomitantly in immunocompromised patients. We performed a systematic search of published in vitro activity for nine approved and investigational antivirals to understand the spectrum of in vitro activity against dsDNA viruses.

METHODS

A literature search was performed (PubMed and the WoS Core Collection) using keywords related to: 1) targeted approved/developmental antivirals (acyclovir, artesunate, brincidofovir, cidofovir, cyclopropavir (filociclovir), foscarnet, ganciclovir, letermovir, and maribavir); 2) pathogenic dsDNA viruses; 3) in vitro activity. We summarized data from 210 publications.

RESULTS

Activity against ≤3 viruses was documented for maribavir (cytomegalovirus, Epstein-Barr virus), and letermovir, while activity against > 3 viruses was shown for ganciclovir, cidofovir, acyclovir, foscarnet, cyclopropavir, artesunate, and brincidofovir. The EC₅₀ values of brincidofovir were the lowest, ranging from 0.001 to 0.27 μM, for all viruses except papillomaviruses. The next most potent agents included cidofovir, ganciclovir, foscarnet, and acyclovir with EC₅₀ values between 0.1 μM and >10 μM for cytomegalovirus, herpes simplex virus, and adenovirus.

CONCLUSION

Most of the identified antivirals had in vitro activity against more than one dsDNA virus. Brincidofovir and cidofovir have broad-spectrum activity, and brincidofovir has the lowest EC₅₀ values. These findings could assist clinical practice and developmental research.

[Genital warts in HIV-infected individuals]

Anogenital warts (condylomata acuminata) are much more frequent in human immunodeficiency (HIV)-positive patients compared to HIV-negative individuals. Anogenital warts of HIV-infected patients differ from those of HIV-negative individuals with respect to their spread, occurrence on more unusual anatomical sites, human papillomavirus (HPV)-type spectrum, tendency to recur, and risk of malignant transformation. Between 18 and 56% of anogenital warts of HIV-positive patients harbor high-grade dysplasia. Therefore, anogenital warts of HIV-infected patients should be preferentially treated with ablative methods and should be evaluated histopathologically. Gender-neutral prophylactic HPV vaccination of HPV-naive boys and girls could also lead to a significant reduction of anogenital warts in this patient group in the future.

Human Papillomavirus DNA Methylation Predicts Response to Treatment Using Cidofovir and Imiquimod in Vulval Intraepithelial Neoplasia 3

Purpose: Response rates to treatment of vulval intraepithelial neoplasia (VIN) with imiquimod and cidofovir are approximately 57% and 61%, respectively. Treatment is associated with significant side effects and, if ineffective, risk of malignant progression. Treatment response is not predicted by clinical factors. Identification of a biomarker that could predict response is an attractive prospect. This work investigated HPV DNA methylation as a potential predictive biomarker in this setting.Experimental Design: DNA from 167 cases of VIN 3 from the RT3 VIN clinical trial was assessed. HPV-positive cases were identified using Greiner PapilloCheck and HPV 16 type-specific PCR. HPV DNA methylation status was assessed in three viral regions: E2, L1/L2, and the promoter, using pyrosequencing.Results: Methylation of the HPV E2 region was associated with response to treatment. For cidofovir (n = 30), median E2 methylation was significantly higher in patients who responded (P ≤ 0.0001); E2 methylation >4% predicted response with 88.2% sensitivity and 84.6% specificity. For imiquimod (n = 33), median E2 methylation was lower in patients who responded to treatment (P = 0.03; not significant after Bonferroni correction); E2 methylation <4% predicted response with 70.6% sensitivity and 62.5% specificity.Conclusions: These data indicate that cidofovir and imiquimod may be effective in two biologically defined groups. HPV E2 DNA methylation demonstrated potential as a predictive biomarker for the treatment of VIN with cidofovir and may warrant investigation in a biomarker-guided clinical trial. Clin Cancer Res; 23(18); 5460-8. ©2017 AACR.

Topical therapies for the treatment of anal high-grade squamous intraepithelial lesions

Anal cancer may be prevented by treating anal high-grade squamous intraepithelial lesions (HSIL). Ablative therapies are the most commonly used treatments, but they may not be appropriate for all patients including those with extensive HSIL or bleeding diastheses. Researchers have studied topical therapies for human papillomavirus related lesions including anal HSIL. These therapies include patient-applied 5-fluorouracil, imiquimod and cidofovir, and provider-applied trichloroacetic acid. This review will discuss literature supporting efficacy of these products, which is based mainly on case series with few controlled trials having been conducted. Side effects are common with patient-applied topical therapy often requiring dose reduction and medication to treat pain. However, treatment discontinuations are infrequent. This review will also discuss some approaches to the use of these products in clinical practice.

Recent advances in understanding and preventing human papillomavirus-related disease

High-risk human papillomaviruses (hrHPV) are responsible for anogenital and oropharyngeal cancers, which together account for at least 5% of cancers worldwide. Industrialised nations have benefitted from highly effective screening for the prevention of cervical cancer in recent decades, yet this vital intervention remains inaccessible to millions of women in low- and middle-income countries (LMICs), who bear the greatest burden of HPV disease. While there is an urgent need to increase investment in basic health infrastructure and rollout of prophylactic vaccination, there are now unprecedented opportunities to exploit recent scientific and technological advances in screening and treatment of pre-invasive hrHPV lesions and to adapt them for delivery at scale in resource-limited settings. In addition, non-surgical approaches to the treatment of cervical intraepithelial neoplasia and other hrHPV lesions are showing encouraging results in clinical trials of therapeutic vaccines and antiviral agents. Finally, the use of next-generation sequencing to characterise the vaginal microbial environment is beginning to shed light on host factors that may influence the natural history of HPV infections. In this article, we focus on recent advances in these areas and discuss their potential for impact on HPV disease.

Synthesis and Antiviral Evaluation of Octadecyloxyethyl Benzyl 9-[(2-Phosphonomethoxy)ethyl]guanine (ODE-Bn-PMEG), a Potent Inhibitor of Transient HPV DNA Amplification

Human papillomavirus (HPV) high-risk genotypes such as HPV-16 and HPV-18 cause the majority of anogenital tract carcinomas, including cervical cancer, the second most common malignancy in women worldwide. Currently there are no approved antiviral agents that reduce or eliminate HPV and reverse virus-associated pathology. We synthesized and evaluated several alkoxyalkyl acyclic nucleoside phosphonate diesters and identified octadecyloxyethyl benzyl 9-[(2-phosphonomethoxy)ethyl]guanine (ODE-Bn-PMEG) as an active compound which strongly inhibited transient amplification of HPV-11, -16, and -18 origin-containing plasmid DNA in transfected cells at concentrations well below its cytotoxic concentrations. ODE-Bn-PMEG demonstrated increased uptake in human foreskin fibroblast cells and was readily converted in vitro to the active antiviral metabolite, PMEG diphosphate. The P-chiral enantiomers of ODE-Bn-PMEG were obtained and appeared to have equivalent antiviral activities against HPV. ODE-Bn-PMEG is a promising candidate for the local treatment of HPV-16 and HPV-18 and other high-risk types, an important unmet medical need.

[HPV-induced anal lesions]

Human papillomavirus (HPV) infections belong to the most common sexually transmitted infections. To date, more than 200 completely classified HPV-types have been reported, and those belonging to the genus alpha predominantly infect the anogenital region. Condylomata acuminata are caused by the two low-risk types HPV6 and HPV11 in more than 90 % of cases. Treatment of genital warts might be either ablative (e.g. electrocautery, surgical excision, or laser therapy) or topical (e.g. podophyllotoxine, trichloroacetic acid, or imiquimod), and depends on the size, location, morphology and anatomical region. Recurrences after treatment are frequent. Therefore, combination therapies (e.g. topical and ablative) play an important role in daily routine. HIV-infected individuals, especially HIV-positive MSM, have a strongly increased risk for anal dysplasia and anal cancer. Condylomata acuminata and a large proportion of anal dysplasia and anal carcinoma are preventable by prophylactic HPV-vaccination.

The broad-spectrum anti-DNA virus agent cidofovir inhibits lung metastasis of virus-independent, FGF2-driven tumors

The FDA-approved anti-DNA virus agent cidofovir (CDV) is being evaluated in phase II/III clinical trials for the treatment of human papillomavirus (HPV)-associated tumors. However, previous observations had shown that CDV also inhibits the growth of vascular tumors induced by fibroblast growth factor-2 (FGF2)-transformed FGF2-T-MAE cells. Here, we demonstrate that CDV inhibits metastasis induced by FGF2-driven, virus-independent tumor cells. Pre-treatment of luciferase-expressing FGF2-T-MAE cells with CDV reduced single cell survival and anchorage-independent growth in vitro and lung metastasis formation upon intravenous inoculation into SCID mice. This occurred in the absence of any effect on homing of FGF2-T-MAE cells to the lungs and on the growth of subconfluent cell cultures or subcutaneous tumors in mice. Accordingly, CDV protected against lung metastasis when given systemically after tumor cell injection. Lung metastases in CDV-treated mice showed reduced Ki67 expression and increased nuclear accumulation of p53, indicating that CDV inhibits metastasis by affecting single cell survival properties. The anti-metastatic potential of CDV was confirmed on B16-F10 melanoma cells, both in zebrafish embryos and mice. These findings suggest that CDV may have therapeutic potential as an anti-metastatic agent and warrants further study to select those tumor types that are most likely to benefit from CDV therapy.

Medical and surgical interventions for the treatment of usual-type vulval intraepithelial neoplasia

BACKGROUND

Usual-type vulval intraepithelial neoplasia (uVIN) is a pre-cancerous condition of the vulval skin. Also known as high-grade VIN, VIN 2/3 or high-grade vulval squamous intraepithelial lesion (HSIL), uVIN is associated with high-risk subtype human papilloma virus (HPV) infection. The condition causes distressing vulval symptoms in the majority of affected women and may progress to vulval cancer, therefore is usually actively managed. There is no consensus on the optimal management of uVIN. High morbidity and recurrence rates associated with surgical treatments make less invasive treatments highly desirable.

OBJECTIVES

To determine which interventions are the most effective, safe and tolerable for treating women with uVIN.

SEARCH METHODS

We searched the Cochrane Gynaecological Cancer Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Issue 8 2015, MEDLINE and EMBASE (up to 1 September 2015). We also searched registers of clinical trials, abstracts of scientific meetings, reference lists of included studies and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that assessed medical and surgical interventions in women with uVIN. If no RCTs were available, we included non-randomised studies (NRSs) with concurrent comparison groups that controlled for baseline case mix in multivariate analysis.

DATA COLLECTION AND ANALYSIS

We used Cochrane methodology with two review authors independently extracting data and assessing risk of bias. Where possible, we synthesised data in meta-analyses using random-effects methods. Network meta-analysis was not possible due to insufficient data.

MAIN RESULTS

We included six RCTs involving 327 women and five NRSs involving 648 women. The condition was variously named by investigators as uVIN, VIN2/3 or high-grade VIN. Five RCTs evaluated medical treatments (imiquimod, cidofovir, indole-3 carbinol), and six studies (one RCT and five NRSs) evaluated surgical treatments or photodynamic therapy. We judged two RCTs and four NRSs to be at a high or unclear risk of bias; we considered the others at relatively low risk of bias. Types of outcome measures reported in NRSs varied and we were unable to pool NRS data. Medical interventions: Topical imiquimod was more effective than placebo in achieving a response (complete or partial) to treatment at five to six months post-randomisation (three RCTs, 104 women; risk ratio (RR) 11.95, 95% confidence interval (CI) 3.21 to 44.51; high-quality evidence). At five to six months, a complete response occurred in 36/62 (58%) and 0/42 (0%) women in the imiquimod and placebo groups, respectively (RR 14.40, 95% CI 2.97 to 69.80). Moderate-quality evidence suggested that the complete response was sustained at one year (one RCT, nine complete responses out of 52 women (38%)) and beyond, particularly in women with smaller VIN lesions. Histologically confirmed complete response rates with imiquimod versus cidofovir at six months were 45% (41/91) and 46% (41/89), respectively (one RCT, 180 women; RR 1.00, 95% CI 0.73 to 1.37; moderate-quality evidence). Twelve-month data from this trial are awaited; however, interim findings suggested that complete responses were sustained at 12 months. Only one trial reported vulval cancer at one year (1/24 and 2/23 in imiquimod and placebo groups, respectively). Adverse events were more common with imiquimod than placebo and dose reductions occurred more frequently in the imiquimod group than in the placebo group (two RCTs, 83 women; RR 7.77, 95% CI 1.61 to 37.36; high-quality evidence). Headache, fatigue and discontinuation were slightly more common with imiquimod than cidofovir (moderate-quality evidence). Quality of life scores reported in one trial (52 women) were not significantly different for imiquimod and placebo. The evidence of effectiveness of topical treatments in immunosuppressed women was scant. There was insufficient evidence on other medical interventions. Surgical and other interventions: Low-quality evidence from the best included NRS indicated, when data were adjusted for confounders, that there was little difference in the risk of VIN recurrence between surgical excision and laser vaporisation. Recurrence occurred in 51% (37/70) of women overall, at a median of 14 months, and was more common in multifocal than unifocal lesions (66% versus 34%). Vulval cancer occurred in 11 women (15.1%) overall at a median of 71.5 months (9 to 259 months). The risk of vulval cancer did not differ significantly between excision and laser vaporisation in any of the NRSs; however, events were too few for robust findings. Alternative surgical procedures that might be as effective include Cavitron ultrasonic surgical aspiration (CUSA) and loop electrosurgical excision (LEEP) procedures, based on low- to very low-quality evidence, respectively. Very low-quality evidence also suggested that photodynamic therapy may be a useful treatment option.We found one ongoing RCT of medical treatment (imiquimod) compared with surgical treatment.

AUTHORS' CONCLUSIONS

Topical treatment (imiquimod or cidofovir) may effectively treat about half of uVIN cases after a 16-week course of treatment, but the evidence on whether this effect is sustained is limited. Factors predicting response to treatment are not clear, but small lesions may be more likely to respond. The relative risk of progression to vulval cancer is uncertain. However, imiquimod and cidofovir appear to be relatively well tolerated and may be favoured by some women over primary surgical treatment.There is currently no evidence on how medical treatment compares with surgical treatment. Women who undergo surgical treatment for uVIN have about a 50% chance of the condition recurring one year later, irrespective of whether treatment is by surgical excision or laser vaporisation. Multifocal uVIN lesions are at a higher risk of recurrence and progression, and pose greater therapeutic dilemmas than unifocal lesions. If occult cancer is suspected despite a biopsy diagnosis of uVIN, surgical excision remains the treatment of choice. If occult cancer is not a concern, treatment needs to be individualised to take into account the site and extent of disease, and a woman's preferences. Combined modalities may hold the key to optimal treatment of this complex disease.

Topical cidofovir to treat high-grade anal intraepithelial neoplasia in HIV-infected patients: a pilot clinical trial

OBJECTIVE

To evaluate the efficacy of 1% topical cidofovir cream for the treatment of anal high-grade squamous intraepithelial lesions (HSILs) in HIV-infected individuals.

DESIGN

Single-arm, open-label, pilot clinical trial.

METHODS

The study medication was applied intraanally three times per week for 4 weeks. Lesions were assessed with high-resolution anoscopy and biopsy at weeks 12 and 24. The primary endpoint was complete remission (CR) at week 12, defined as clinical and histological remission. We also evaluated partial remission defined as regression to low-grade squamous intraepithelial lesion.

RESULTS

We included 17 HIV-infected patients with intraanal HSIL. Median (interquartile range) age was 36 years (28-41), median (interquartile range) CD4 cell count was 545 cells/μl (358-630), and viral load was less than 50  copies/ml in 93.7%. Two patients were lost to follow-up, one of them did not apply treatment. At 12 weeks, in the intention-to-treat population, 10 out of 16 patients [62.5%; 95% confidence interval (CI), 38.2-85.7%] had achieved CR. At 24 weeks, seven of the 10 patients (70%; 95% CI, 47-93%) remained in CR, but two out of 10 patients (20%; 95% CI, 0-40%) presented HSIL. One patient did not attend the visit at 24 weeks. Three patients with persistent HSIL at 12 weeks improved at 24 weeks (partial response in one and CR in two). The mean number of human papillomavirus genotypes decreased from 5.2 to 2.7 at 12 weeks (P = 0.002). Local adverse effects were frequent (81%), although there were no discontinuations because of adverse events.

CONCLUSION

One percent topical cidofovir could be an appropriate alternative therapy in HIV-infected patients with anal HSIL.

CLINICAL TRIAL

gov unique identifier: NCT01946009.

Investigational drugs for treating anal cancer and future perspectives

INTRODUCTION

Anal cancer is a relatively rare malignancy which comprises about 2.5% of all digestive system malignancies in the United States. The majority of cases are squamous cell carcinoma which is closely related to human papilloma virus (HPV) infection. Despite high cure rates with chemoradiation alone, 10 - 20% of patients do develop metastatic disease with little data to guide their treatment.

AREAS COVERED

In this review article, the authors describe the current standard treatment of early and advanced squamous cell carcinoma of the anal canal based on published data. The authors then describe the new approaches to the disease, focusing on new radio sensitizing agents, systemic targeted drugs and immunotherapy.

EXPERT OPINION

The authors believe that current standard treatment options for squamous cell carcinoma of the anal canal are well defined with acceptable results. However the major challenge in the treatment of anal cancer is the lack of randomized or even large single arm Phase II trials due to rarity of the disease, especially in the metastatic disease. But we are slowly making progress. Currently, the most promising areas of research are immunotherapy, targeted therapy and even HPV prevention. We are eagerly anticipating the results of these studies in order to expand the treatment armamentarium.

Usual vulval intraepithelial neoplasia in HIV-positive women - a case series

Usual or undifferentiated type vulval intraepithelial neoplasia (VIN) is more common in young women and is usually associated with high-risk human papillomavirus infection. It is associated with the development of basaloid or warty squamous cell carcinoma. Studies have shown that HIV-positive women have an increased risk of VIN and invasive vulval carcinoma, but there is a paucity of data about this cohort of women. The objective of this study was to describe the clinical features and treatment responses of HIV-positive women diagnosed with VIN in a specialist vulval dermatology clinic. HIV-positive women diagnosed with VIN from 2007 to 2013 were retrospectively identified. Data were collected on demographics, clinical features, treatments and outcomes. Seven cases were retrospectively identified. The median CD4 cell count at presentation was 500 cells/mm³ (range 59-761). Five had multifocal VIN. Five were treated with imiquimod alone, one had surgical excision and one patient was treated with imiquimod and surgery. Five of the seven had complete resolution of disease. HIV-positive patients with VIN had good responses to treatment with imiquimod. They were likely to be stable on combination antiretroviral therapy at presentation, have multifocal disease and concurrent vaginal, anal or cervical intraepithelial neoplasia.

Medical interventions for high-grade vulval intraepithelial neoplasia

BACKGROUND

This is an updated version of a review first published in theCochrane Database of Systematic Reviews, Issue 4, in 2011. Vulval intraepithelial neoplasia (VIN) is a pre-cancerous condition of the vulval skin and its incidence is increasing in women under 50 years. High-grade VIN (also called usual-type VIN (uVIN) or VIN 2/3 or high-grade vulval intraepithelial lesion) is associated with human papilloma virus (HPV) infection and may progress to vulval cancer, therefore is usually actively managed. There is no consensus on the optimal management of high-grade VIN; and the high morbidity and relapse rates associated with surgical interventions make less invasive interventions highly desirable.

OBJECTIVES

To evaluate the effectiveness and safety of medical (non-surgical) interventions for high-grade VIN.

SEARCH METHODS

We searched the Cochrane Gynaecological Cancer Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 3), MEDLINE and EMBASE (up to 30 March 2015). We also searched registers of clinical trials, abstracts of scientific meetings, reference lists of included studies and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that assessed non-surgical interventions in women diagnosed with high-grade VIN.

DATA COLLECTION AND ANALYSIS

We used Cochrane methodology with two review authors independently abstracting data and assessing risk of bias. Where possible, we synthesised data in meta-analyses using random effects methods.

MAIN RESULTS

Five trials involving 297 women with high-grade VIN (defined by trial investigators as VIN 2/3 or VIN 3 or 'high-grade' lesions) met our inclusion criteria: three trials assessed the effectiveness of topical imiquimod versus placebo; one assessed topical cidofovir versus topical imiquimod; and one assessed low- versus high-dose indole-3-carbinol in similar types of participants. Three trials were at a moderate to low risk of bias, two were at a potentially high risk of bias.Meta-analysis of the three trials comparing topical imiquimod 5% cream to placebo found that women in the active treatment group were more likely to show an overall response (complete and partial response) to treatment at five to six months compared with the placebo group (Risk Ratio (RR) 11.95, 95% confidence interval (CI) 3.21 to 44.51; participants = 104; studies = 3; I(2) = 0%; high-quality evidence). A complete response at five to six months occurred in 36/62 (58%) and 0/42 (0%) participants in the active and placebo groups, respectively (RR 14.40, 95% CI 2.97 to 69.80; participants = 104; studies = 3; I(2) = 0%). A single trial reported 12-month follow-up, which revealed a sustained effect in overall response in favour of the active treatment arm at 12 months (RR 9.10, 95% CI 2.38 to 34.77; moderate-quality evidence), with 9/24 (38%) and 0/23 (0%) complete responses recorded in the active and placebo groups respectively. Progression to vulval cancer was also documented in this trial (one versus two participants in the active and placebo groups, respectively) and we assessed this evidence as low-quality. Only one trial reported adverse events, including erythema, erosion, pain and pruritis at the site of the lesion, which were more common in the imiquimod group. Dose reductions occurred more frequently in the active treatment group compared with the placebo group (19/47 versus 1/36 participants; RR 7.77, 95% CI 1.61 to 37.36; participants = 83; studies = 2; I(2) = 0%; high-quality evidence). Only one trial reported quality of life (QoL) and there were no significant differences between the imiquimod and placebo groups.For the imiquimod versus cidofovir trial, 180 women contributed data. The overall response at six months was similar for the imiquimod and cidofovir treatment groups with 52/91 (57%) versus 55/89 (62%) participants responding, respectively (RR 0.92, 95% CI 0.73 to 1.18). A complete response occurred in 41 women in each group (45% and 46%, respectively; RR 1.00, 95% CI 0.73 to 1.37). Although not statistically different, total adverse events were slightly more common in the imiquimod group of this trial with slightly more discontinuations occurring in this group. Longer term response data from this trial are expected.The small trial comparing two doses of indole-3-carbinol contributed limited data. We identified five ongoing randomised trials of various interventions for VIN.

AUTHORS' CONCLUSIONS

Topical imiquimod appears to be a safe and effective treatment for high-grade VIN (uVIN), even though local side-effects may necessitate dose reductions. However, longer term follow-up data are needed to corroborate the limited evidence that response to treatment is sustained, and to assess any effect on progression to vulval cancer. Available evidence suggests that topical cidofovir may be a good alternative to imiquimod; however, more evidence is needed, particularly regarding the relative effectiveness on longer term response and progression. We await the longer-term response data and the results of the five ongoing trials.

HPV and anal cancer in HIV-infected individuals: a review

HIV infection is one of the strongest risk factors for anal squamous cell cancer (ASCC). Most ASCC are caused by HPV, and most HPV-associated ASCC are caused by HPV-16. Anal HPV infections are very common in men who have sex with men (MSM), and nearly universal among HIV-infected MSM. High-grade anal intraepithelial neoplasia (HGAIN), the precursor for ASCC, is present in about 30 % of HIV+ MSM, but neither the progression rate to ASCC nor the regression rate are known. The incidence rate of ASCC among HIV-infected people has risen in the first decade after cART became available, but appears to be plateauing recently. Anal cytology has poor sensitivity and specificity. High resolution anoscopy (HRA) is advocated by some as a screening tool in high-risk groups, but is cumbersome and time-consuming and it is unknown whether HRA followed by treatment of HGAIN prevents ASCC. More research is needed on progression and regression rates of HGAIN, on effective therapy of HGAIN, and on biomarkers that predict HGAIN or anal cancer. HPV vaccination and earlier start of cART may prevent most anal cancers in the long run.

Targeted ablation of perianal high-grade dysplasia in men who have sex with men: an alternative to mapping and wide local excision

BACKGROUND

Perianal high-grade dysplasia (Bowen disease) is traditionally treated with mapping and wide excision with possible grafting rather than local ablation.

OBJECTIVE

The aim of this study is to examine the results of high-grade perianal dysplasia ablation.

DATA SOURCES

Data for this study were derived from a retrospective chart review at a surgical practice screening and treating patients for high-grade dysplasia between July 1998 and June 2013.

STUDY SELECTION

The patients included were men who have sex with men and are undergoing perianal dysplasia ablation.

INTERVENTION

Ablation of perianal dysplasia with electrocautery, laser, or infrared coagulation was performed.

MAIN OUTCOME MEASURES

The primary outcomes measured were the recurrence of perianal dysplasia postablation and factors affecting recurrence.

RESULTS

Seventy HIV-positive and 11 HIV-negative patients enrolled; the median ages were 44.7 and 42.8 years. Median follow-up times for HIV-positive and HIV-negative patients were 4.62 and 3.53 years, and the median numbers of treatments were 4 and 1, p = 0.004. The median number of lesions treated was 1 for both groups. Only 1 HIV-negative patient had a recurrence 8 months after treatment. For HIV-positive patients, the Kaplan-Meier probability of recurrence at 1, 3, and 5 years was 38% (95% CI 26-50), 59% (95% CI 47-72), and 68% (95% CI 55-81) after the first ablation with no difference for subsequent treatments. HIV-positive patients had a relative risk of perianal high-grade squamous intraepithelial lesions of 3.72 (95% CI 2.10-6.60) compared with HIV-negative patients (p ≤ 0.0001). In multivariate analysis, only each increase in intra-anal high-grade squamous intraepithelial lesions significantly increased recurrence (HR 1.13, 95% CI 1.00-1.28, p = 0.002). Only 3 patients with perianal high-grade squamous intraepithelial lesions did not have canal dysplasia. Perianal cancer developed in 3 after being lost to follow-up.

LIMITATIONS

This is a retrospective analysis of 1 experienced surgeon's results. No precise way exists to accurately determine the size of the disease.

CONCLUSIONS

Perianal dysplasia can be successfully ablated, but recurrence remains high. Almost all patients have anal canal dysplasia. HIV-positive patients are at the greatest risk for disease and recurrence. An increased number of high-grade canal lesions increases recurrence.

Activity, safety, and feasibility of cidofovir and imiquimod for treatment of vulval intraepithelial neoplasia (RT³VIN): a multicentre, open-label, randomised, phase 2 trial

BACKGROUND

Vulval intraepithelial neoplasia is a skin disorder affecting the vulva that, if left untreated, can become cancerous. Currently, the standard treatment for patients with vulval intraepithelial neoplasia is surgery, but this approach does not guarantee cure and can be disfiguring, causing physical and psychological problems, particularly in women of reproductive age. We aimed to assess the activity, safety, and feasibility of two topical treatments--cidofovir and imiquimod--as an alternative to surgery in female patients with vulval intraepithelial neoplasia.

METHODS

We recruited female patients (age 16 years or older) from 32 centres to an open-label, randomised, phase 2 trial. Eligibility criteria were biopsy-proven vulval intraepithelial neoplasia grade 3 and at least one lesion that could be measured accurately. We randomly allocated patients to topical treatment with either 1% cidofovir (supplied as a gel in a 10 g tube, to last 6 weeks) or 5% imiquimod (one 250 mg sachet for every application), to be self-applied three times a week for a maximum of 24 weeks. Randomisation (1:1) was done by stratified minimisation via a central computerised system, with stratification by hospital, disease focality, and presentation stage. The primary endpoint was a histologically confirmed complete response at the post-treatment assessment visit 6 weeks after the end of treatment (a maximum of 30 weeks after treatment started). Analysis of the primary endpoint was by intention to treat. Secondary outcomes were toxic effects (to assess safety) and adherence to treatment (to assess feasibility). We present results after all patients had reached the primary endpoint assessment point at 6 weeks; 2-year follow-up of complete responders continues. This trial is registered with Current Controlled Trials, ISRCTN 34420460.

FINDINGS

Between Oct 21, 2009, and Jan 11, 2013, 180 participants were enrolled to the study; 89 patients were randomly allocated cidofovir and 91 were assigned imiquimod. At the post-treatment assessment visit, a complete response had been achieved by 41 (46%; 90% CI 37·0-55·3) patients allocated cidofovir and by 42 (46%; 37·2-55·3) patients assigned imiquimod. After 6 weeks of treatment, 156 (87%) patients (78 in each group) had adhered to the treatment regimen. Five patients in the cidofovir group and seven in the imiquimod group either withdrew or were lost to follow-up before the first 6-week safety assessment. Adverse events of grade 3 or higher were reported in 31 (37%) of 84 patients allocated cidofovir and 39 (46%) of 84 patients assigned imiquimod; the most frequent grade 3 and 4 events were pain in the vulva, pruritus, fatigue, and headache.

INTERPRETATION

Cidofovir and imiquimod were active, safe, and feasible for treatment of vulval intraepithelial neoplasia and warrant further investigation in a phase 3 setting. Both drugs are effective alternatives to surgery for female patients with vulval intraepithelial neoplasia after exclusion of occult invasive disease.

FUNDING

Cancer Research UK.

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.

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.