Cidofovir modulated gene expression in recurrent respiratory papillomatosis

Hoarseness

Hoarseness is a common problem, typically of transient nature. When hoarseness does not resolve, or when it is associated with concerning symptoms, it is important to consider a wide differential and refer to an otolaryngologist. This article discusses the physiology of the voice and possible causes of dysphonia, and explores when it warrants further work-up by ENT. A discussion of diagnostic techniques and the myriad of tools to treat hoarseness follows. Additionally, the role of reflux in dysphonia is examined with a critical eye to aid in accurate assessment of the patient's complaint.

Systematic review of intralesional cidofovir dosing regimens in the treatment of recurrent respiratory papillomatosis

OBJECTIVE

Surgical management of recurrent respiratory papillomatosis (RRP) usually involves resection via microlaryngoscopy. Intralesional injection of cidofovir has been shown to be an effective adjuvant treatment, but remains unlicensed. United Kingdom General Medical Council guidelines recommend the prescribing doctor should "be satisfied that there is a sufficient evidence base and/or experience of using the medicine to demonstrate its safety and efficacy". This study reviews the published dosing regimens of intralesional cidofovir in the treatment of RRP in order to provide a precedent for those that wish to prescribe it.

METHODS

A systematic review of the literature was undertaken using Medline, EMBASE and CINAHL. Articles describing the use of intralesional cidofovir for RRP were reviewed. Information regarding cidofovir concentration, volume, total dose, number of treatments, interval between treatments, overall treatment period and follow up was extracted.

RESULTS

Fifty-one articles were identified. Concentration of cidofovir injected ranged from 0.0001mg/ml to 37.5mg/ml, with 5 to 7.5mg/ml being the most common. The volume of cidofovir solution injection ranged from 0.1 to 20ml. The total dose per injection ranged from 0.15 to 105mg. There was wide variation in dosing regimens with different intervals between endoscopies, number of injections and total doses delivered.

CONCLUSIONS

Based on this published literature, the precedent for prescribing intralesional cidofovir supports a concentration of 5 to 7.5mg/ml. Volumes up to 5ml per injection are routinely used. Total dose and frequency of cidofovir administration is highly variable. The need for repeat doses of cidofovir should be judged on an individual basis.

[The schedule of intralesional papillomatosis treatment with cidofovir]

INTRODUCTION

Recurrent respiratory papillomatosis (RRP) is a rare disease in children and adults. It is characterized by proliferation of benign squamous cell papillomas within the respiratory-digestive tract, predominantly the larynx. Standard treatment consists of surgical excision of papillomata to maintain airway patency and voice quality. For last several years cidofovir is the most contemporary adjuvant anti-viral treatment for recurrent respiratory papillomatosis and its topical use is widely described.

MATERIAL AND METHODS

Intralesional cidofovir therapy was given to 20 patients treated for laryngeal papillomas in the Department of Otolaryngology in Poznan between I-XII.2009. The character of the lesion differed: from one anatomical site and moderate growth to four or five localizations with heavy extension. The number of cidofovir injections per patient varied from one to six times and the volume of solution ranges from 1-12 ml. The cidofovir injections were combined with laser or mechanical excision of the lesions. In disperse papillomata the injections administered in particular anatomical sites in 4-6 weeks period. In massive lesions injections were repeated in the same anatomical site.

RESULTS

Complete remission was observed in 3 out of 20 patients. 12 patients show remission in a place of cidofovir injection. In 4 patients during the 4 week observation new foci of papillomatosis occurred. In two patients hepatic toxic side effect were observed.

CONCLUSIONS

Intralesional cidofovir injection has been shown to be an effective an safe therapy for laryngeal papilloma and should be considered in those patients who experienced disease relapse.

Potential risk factors associated with the use of cidofovir to treat benign human papillomavirus-related disease

BACKGROUND

Cidofovir is currently being used off-licence to treat different viral infections, such as benign low-risk human papillomavirus (HPV)-related recurrent respiratory papillomatosis (RRP). There are concerns over the safety of this practice as rat studies demonstrated a high malignant transformation rate. As yet, there are no clinical reports of cidofovir-induced malignant changes in humans.

METHODS

Telomerase immortalised human keratinocytes (hTert) stably expressing E6 proteins from either low-risk HPV6b or high-risk HPV16 and vector control cells were treated with either low-dose (5 microg/ml) or higher dose (30 microg/ml) cidofovir for 2 days and the effects evaluated by clonogenic survival assays. Based on these results, gene expression microarray analysis was performed on cidofovir-treated low-risk E6 and vector cells before, during and after drug treatment, and the results verified by real-time PCR.

RESULTS

Both low-risk and high-risk E6-expressing cells show significantly improved long-term survival compared with vector control cells when exposed to 5 microg/ml cidofovir for 2 days, (hTert T6E6 P=0.0007, hTert T16E6 P=0.00023 and hTert vector control P=0.62). Microarray and real-time PCR analyses of low-dose cidofovir-treated low-risk E6-expressing cells revealed changes in gene expression that are known to be associated with malignant progression, which were not observed in drug-treated vector control cells.

CONCLUSIONS

This is the first report that cidofovir can both increase cell survival and induce alterations in gene expression that are known to be associated with malignant transformation in cells transduced only with the E6 gene from low-risk HPV. It is our belief that these data provide cause for concern over the off-license use of this drug to treat RRP.