Cidofovir efficacy in recurrent respiratory papillomatosis: a randomized, double-blind, placebo-controlled study.
We performed a prospective, double-blind, placebo-controlled, longitudinal adjuvant therapy trial to determine the efficacy of cidofovir in the treatment of severe recurrent respiratory papillomatosis (RRP). Although results of case series suggest that cidofovir may decrease the frequency and rapidity of papilloma regrowth, no blinded placebo-controlled studies have demonstrated efficacy.
                Adults and children (n = 19) with aggressive RRP received either active drug (cidofovir) or placebo. When surgical intervention was needed, drug or placebo was injected into affected areas after surgical removal of disease. The following measures were made at baseline and at 2-month intervals for the course of 12 months: Derkay papilloma severity grading scale, Voice Handicap Index, Health-Related Quality of Life, and total number of procedures performed over 12 months.
                At 2- and 12-month follow-ups, there was a significant (p < .05) improvement in the Derkay Severity Score within the cidofovir and placebo groups, but no difference between groups, and no difference between groups in the number of procedures performed. Significant improvement was found in Voice Handicap Index scores in the cidofovir group at the 12-month follow-up. No differences were seen in Health-Related Quality of Life.
                A randomized, blinded, placebo-controlled trial is necessary in the study of RRP, because the natural history of the disease can include remissions and reactivations. We found a significant improvement in the Derkay Severity Score 12 months after the baseline assessment in patients treated with cidofovir. This effect, however, was also seen in the placebo group. Accordingly, we were unable to provide proof of efficacy of cidofovir in the treatment of RRP.
There is insufficient evidence to support the efficacy of antiviral agents as adjuvant therapy in the management of recurrent respiratory papillomatosis in children or adults. The included randomised controlled trial showed no advantage of intralesional cidofovir over placebo at 12 months. The study was limited by a small sample size and a change in the cidofovir concentration midway through the trial, from 0.3 mg/ml in children and 0.75 mg/ml in adults, to 5 mg/ml in both adults and children. An adequately powered randomised controlled trial of intra-lesional cidofovir, consistently using higher concentrations of cidofovir in comparison with injected placebo, would be required to determine effectiveness convincingly. Future studies must include health-related quality of life and symptom-based outcome measures.