Follow-up of HPV DNA Copy Number in Cidofovir Therapy of Recurrent Respiratory Papillomatosis

Abstract

Background: Cidofovir is a cytosine nucleoside analogue antiviral drug given as an adjuvant threapy in recurrent respiratory papillomatosis (RRP). Materials and Methods: Intralesional cidofovir therapy was given to a 14-year-old male patient. The papilloma severity score (PSS) of Derkay et al. was used for follow-up. Serial fresh-frozen biopsies were taken from the lesions in the larynx and soft palate prior to therapy and during its course. After human papillomavirus (HPV) typing and the determination of the genomic physical state, the HPV DNA copy number was estimated with real-time PCR. Results: All the papillomas harboured HPV 11 DNA in episomal form. Prior to therapy, the HPV copy number fluctuated with time. In the initial treatment period with 2-week-intervals both the viral load and the PSS decreased and a transient complete remission was observed. Subsequently, when the injections were given at longer intervals, the viral load returned to the initial values or greated, fluctuations reappeared and the RRP recurred at a controlled rate. Conclusion: The initial treatment period was successful, as the viral load decreased, and long-term effects of cidofovir might account for the controlled disease as the injection intervals were prolonged.