Safety of intralesional cidofovir in patients with recurrent respiratory papillomatosis: an international retrospective study on 635 RRP patients.

Intralesional use of cidofovir (Vistide(®)) has been one of the mainstays of adjuvant therapy in patients with recurrent respiratory papillomatosis (RRP) since 1998. In 2011, a communication provided by the producer of cidofovir addressed very serious side effects concerning its off-label use. As this was a general warning, it was inconclusive whether this would account for its use in RRP. The aim of this study is to determine whether nephrotoxic, neutropenic, or oncogenic side effects have occurred after intralesional use of cidofovir in patients with RRP. Update of recent developments in RRP, a multicentre questionnaire and a multicentre retrospective chart review. Sixteen hospitals from eleven countries worldwide submitted records of 635 RRP patients, of whom 275 were treated with cidofovir. RRP patients received a median of three intralesional injections (interquartile range 2-6). There were no statistical differences in occurrence of neutropenia or renal dysfunction before and after cidofovir. There was no statistical difference in occurrence of upper airway and tracheal malignancies between the cidofovir and the non-cidofovir group. In this retrospective patient chart review, no clinical evidence was found for more long-term nephrotoxicity, neutropenia or laryngeal malignancies after the administration of intralesional cidofovir in RRP patients.