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

Initial Experience Treating HPV-Related Laryngeal Diseases with Oral Brincidofovir: A Pilot Study

OBJECTIVE

To determine if brincidofovir, an oral analog of cidofovir that achieves high tissue levels of the active metabolite with low systemic toxicity, has an observable effect on HPV-related disease of the larynx.

METHODS

Two patients with laryngeal recurrent respiratory papillomatosis (one each of genotypes 6 and 11) and 1 with recurring aryepiglottic fold carcinoma in situ (genotype 16) received oral brincidofovir according to protocol. Close-range videoendoscopic examinations were done during and after the study period to observe disease behavior in the absence of other interventions, and after subsequent surgical intervention. Disease character and magnitude of recurrence for each patient were compared to their patterns prior to brincidofovir.

RESULTS

Brincidofovir reduced papilloma burden in 1 patient and markedly attenuated the rate and magnitude of recurrence in both. After surgical intervention, Patient 1 remains disease-free at 10 years (7 years from last intervention) and Patient 2 has no symptoms at 8 years. Patient 3 with recurring carcinoma in situ has required less frequent resections and specimens show reduced degrees of dysplasia present only in islands amid normal mucosa at 8 years (currently no evidence of disease at 21 months from last intervention).

CONCLUSION

Brincidofovir appears to attenuate HPV disease of the larynx in this small pilot study, though further investigation is required because of the highly variable nature of the disease and potential confounding factors.

Histologic Review of Cidofovir-Treated Recurrent Respiratory Papillomatosis

Objectives

Recurrent respiratory papillomatosis is currently the most common lesion of the larynx in children. The course of the disease is variable and often requires repetitive surgical interventions to maintain the airway. The predominant concern for disease progression is the possibility of spread to the tracheobronchial tree, as this increases the rates of morbidity and mortality. Cidofovir is an antiviral drug with activity against members of the DNA virus family. Development of local malignant change secondary to use of cidofovir has been a concern. The histopathologic findings from biopsy specimens from children treated with cidofovir have not been previously reported.

Methods

We performed a retrospective review of pediatric operative histologic biopsies and charts of patients treated with intralesional cidofovir and untreated study controls from January 1, 1995, through November 1, 2001.

Results

Ninety-six specimens were evaluated by 2 blinded pathologists. No cases of dysplasia were identified. The most commonly identified finding was an increased nucleus-to-cytoplasm ratio in 8 of 95 cases (8.4%). No cases of abnormal mitoses, prominent nucleoli, or cellular or nuclear enlargement were found.

Conclusions

This is the first report of pathologically evaluated recurrent respiratory papillomatosis specimens taken before and after treatment with intralesional cidofovir. No dysplasia was identified, and there were no significant dysplastic changes in the specimens analyzed.

Imiquimod Injection to Rabbit Vocal Folds: A Preliminary, Preclinical Investigation

Objective Given the recalcitrant nature of recurrent respiratory papillomatosis, targeted therapies to reduce disease burden are fundamental to improved patient care paradigms. We seek to demonstrate the safety of imiquimod injection into vocal fold mucosa by evaluating the degree of laryngeal edema, histopathologic changes to vocal fold structure, and serologic interferon α (IFNα) levels following injection. Study Design Preclinical. Setting Academic institution. Subjects and Methods Six New Zealand White rabbits underwent unilateral injection of 100 µg of sterile imiquimod (1 µg/µL), with 100 µL of normal saline injected into the contralateral vocal fold. Direct laryngoscopy was performed on days 3, 7, and 30 following injection. Larynges from 3 rabbits were harvested on postinjection day 7 for histologic analysis. The remaining 3 rabbit larynges were harvested on day 30. Serial serum samples were drawn for IFNα quantification via immunoassay. Results No signs of respiratory distress were observed at any point. Vocal fold appearance was not clinically divergent between imiquimod and control conditions via serial direct laryngoscopic evaluation. No inflammatory lesions or scarring were identified following injection. Histology showed no signs of acute inflammatory processes or changes in the control or imiquimod injection groups. Serum IFNα increased at days 3 and 7 following imiquimod injection ( P < .0001 and P = .0368, respectively), before returning to baseline by day 14. Conclusions Vocal fold imiquimod injection did not result in notable morbidity in this preclinical model. However, serum IFNα concentrations increased transiently. These data are critical to advance the therapeutic utility of this compound, particularly in the setting of recurrent respiratory papillomatosis.

Mucosal Bridge and Pitting of the True Vocal Fold: An Unusual Complication of Cidofovir Injection

We describe a unique complication of intralaryngeal cidofovir injection and present the case of a patient with recurrent respiratory papillomatosis in whom both a mucosal bridge and a pit of the true vocal fold developed after intralaryngeal cidofovir injection. A 40-year-old man presented with laryngeal papillomatosis 19 years after being treated with surgery and adjuvant radiotherapy for leiomyosarcoma of the cervical esophagus. The patient underwent 5 papillomatosis excisions combined with subepithelial injections of cidofovir to the bilateral true vocal folds at a concentration of 5 mg/mL without any complications. He subsequently received 2 higher-dose cidofovir treatments 6 weeks apart because of a poor response to the previous treatments. Two months later, there was evidence of a large mucosal bridge along the free edge of the right vocal fold and a deep pit in the lateral aspect of the same vocal fold. We conclude that repeated high-dose intralesional injection of cidofovir may result in significant morphological changes to the vocal fold, most likely due to mucosal injury.

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.

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

BACKGROUND

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

PATIENTS AND METHODS

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

DISCUSSION

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

Cidofovir for the Treatment of Recurrent Respiratory Papillomatosis: A Review of the Literature

Recurrent respiratory papillomatosis (RRP) is a rare but potentially severe disease caused by papillomavirus, most often types 6 and 11. The disease, which occurs in both juvenile and adult forms, is characterized by benign epithelial tumors of the airway that most frequently affect the larynx but can also spread along the entire aerodigestive tract. Recurrent respiratory papillomatosis is the most common benign neoplasm of the larynx in children and the second most frequent cause of childhood hoarseness. Standard treatment, which is palliative only, consists of surgical excision of papillomata to maintain airway patency and improve voice quality. Recurrence despite repeated surgical procedures is the rule. To date, incorporation of adjuvant treatments has not been reliably beneficial in altering the disease course. Several case series have described promising results with cidofovir, a cytosine nucleoside analog with antiviral activity. To evaluate the data available on the safety and efficacy of cidofovir for the treatment of RRP, we conducted a MEDLINE search for all case reports or series from January 1966-August 2004 describing cidofovir therapy in either adults or children with RRP. The bibliographies of qualifying articles were also searched for relevant references. In both adults and children with mild-to-severe RRP, intralesional administration of cidofovir directly into the site of papillomata was associated with partial-to-complete regression of papillomata, improvement in voice quality and airway status, and decreased need for surgery. Wide variation in intralesional cidofovir dose (2-57 mg), frequency (every 2-8 wks), and duration (4 mo-4 yrs) was found. Successful outcomes have also been reported with intravenous cidofovir, but data are limited to three case reports. Rash, headache, and precordialgia were the only adverse effects reported with intralesional cidofovir. Nephrotoxicity and neutropenia secondary to either intralesional or intravenous cidofovir were not observed. Long-term risks associated with intralesional administration remain to be seen. Further studies are necessary to determine the most appropriate dose, frequency, and duration of therapy, and to fully characterize the safety profile profile of cidofovir when given intralesionally.

Current diagnostic and management trends for recurrent respiratory papillomatosis

PURPOSE OF REVIEW

The purpose of this review is to discuss recent literature regarding diagnostic and management trends for recurrent respiratory papillomatosis (RRP) published within the past year. This includes a discussion of new information regarding the epidemiology and pathogenesis of RRP and an update on adjuvant therapy and new surgical techniques.

RECENT FINDINGS

Epidemiological studies have confirmed that juvenile-onset RRP is the most common and most aggressive form of the disease. Age at diagnosis is the most important determinant of disease severity, with younger patients requiring significantly more annual surgeries and more likely to have multicentric disease. Distal tracheal or pulmonary RRP is rare, but carries a significant increase in morbidity and mortality. Research into the pathogenesis of RRP has focused on the genetics of HPV infection and host-virus interactions, suggesting a genetic basis for host susceptibility to RRP. At the present time, surgery remains the mainstay of treatment for RRP. However, recurrence after surgery is common and the search for effective adjuvant therapies is ongoing. The antiviral drug cidofovir has demonstrated efficacy against RRP and is considered a promising new adjuvant treatment of this disease. In an attempt to minimize the untoward effects of surgery, the pulsed-dye laser (PDL) has emerged as a safe and efficacious treatment for select patients with RRP.

SUMMARY

While a cure for RRP remains elusive, there has been substantial progress in the diagnosis and management of this disease. Significant advances in clinical and basic science research have dramatically improved our understanding of the epidemiology and pathogenesis of the disease and led to the development of promising new adjuvant therapies and surgical techniques. This has translated to an improved quality of life for many patients with RRP.