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Background Recurrent respiratory papillomatosis (RRP) is mainly associated with human papillomavirus (HPV)6 or HPV11. The purpose of this study was to compare clinical outcome, aggressiveness, and treatment response between HPV6- and HPV11-associated RRP. Methods A retrospective cohort of 55 patients with RRP (1974-2012) was used. Surgical interventions ( n = 814) were analyzed, and complications scored. HPV6/11-specific polymerase chain reaction (PCR) was performed on RRP biopsies. Results Seventy-six percent of patients (42 of 55) were infected with HPV6 and 24% (13 of 55) with HPV11. The HPV11 group had anatomically more widespread disease. The expected number of surgical interventions was higher in the younger age (<22.4 years) HPV11 group, and the older age (<22.4 years) HPV6 group. Regardless of HPV type, earlier age of onset of RRP resulted in a higher number of surgical interventions. Conclusion Anatomically, HPV11-associated RRP behaves more aggressively. Younger patients with HPV11 and older patients with HPV6 experience a worse clinical course of RRP. © 2014 Wiley Periodicals, Inc. Head Neck 37: 1625-1632, 2015 [ABSTRACT FROM AUTHOR]

Background. Cidofovir is a nucleoside analogue that is used off-license to treat recurrent respiratory papillomatosis (RRP) caused by HPV6/11. However, the effect of this drug upon low-risk HPV 6/11 gene expression is unknown. Methods. The expression of E6 was evaluated by RT-PCR in HPV-ve C33A cervical carcinoma cells stably transfected with both low- and high-risk HPV E6 cDNA's and in SiHa (HPV16+ve) cervical carcinoma cells after treatment with 2 doses and durations of exposure to cidofovir. Results. Compared to the vector only transcript, E6 RNA levels showed an 8-fold increase in low-risk and 20-fold increase in high-risk E6-expressing cells. High-risk E6 protein levels were also detected by Western blot in cidofovir-treated C33A Type16 E6-transfected cells. Conclusion. These data may indicate a potential rationale for increased risk of genetic instability and thus transformation due to drug-induced increase in the level of E6. © 2009 Wiley Periodicals, Inc. Head Neck, 2009 [ABSTRACT FROM AUTHOR]

Background. Cidofovir has been reported to have activity against human papillomavirus (HPV) type 16, but no laboratory studies have been performed on HPV type 6, the main cause of recurrent respiratory papillomatosis (RRP). Methods. HPV6b E6 cDNA-based C33A (non-HPV cervical carcinoma) cell line was produced. Two different doses of cidofovir were applied to parent C33A, C33AT6E6, and C33AT16E6 (HPV 16). Growth and flow cytometry analysis were performed. Results. Polymerase chain reaction confirmed HPV6 E6 expression in C33AT6E6 cells. High-dose cidofovir was found to be toxic to all cell lines. Low-dose exposure was found to be toxic to C33AT16E6 cells at 3 days, whereas C33A and C33AT6E6 showed minimal toxicity at 6 days and earlier recovery following drug withdrawal. Conclusions. Cidofovir showed nonspecific toxicity against all 3 cell lines tested. HPV16 E6 expressing cells were more sensitive than parent or HPV6 E6 expressing cells. Cidofovir has no selective advantage for the RRP-related HPV6 E6 expressing cell line. © 2007 Wiley Periodicals, Inc. Head Neck, 2007 [ABSTRACT FROM AUTHOR]