Combined HPV 16 E2 and L1 methylation predict response to treatment with cidofovir and imiquimod in patients with vulval intraepithelial neoplasia

BACKGROUND: Topical cidofovir and imiquimod can effectively treat approximately 55% of patients with vulval intraepithelial neoplasia (VIN), thus avoiding the need for surgery. Human papillomavirus (HPV) E⁢2 gene methylation predicts response to treatment but a methylation measurement is only obtainable in approximately 50% of patients. OBJECTIVE: This work aimed to determine if the applicability and predictive power of the E⁢2 methylation assay could be improved by combining it with the components of a host and viral DNA methylation panel (S5) that has been found to predict disease progression in patients with cervical intraepithelial neoplasia. METHODS: HPV E2 methylation and S5 classifier score were measured in fresh tissue samples collected pre-treatment from 132 patients with biopsy-proven VIN grade 3 who participated in a multicentre clinical trial and were randomised to treatment with cidofovir or imiquimod. RESULTS: Combining HPV16 E⁢2 and HPV16 L⁢1 methylation provides a biomarker that is both predictive of response to topical treatment and that can produce a clinically applicable result for all patients. Patients with HPV 16 L⁢1ℎ𝑖𝑔ℎand HPV 16 E⁢2ℎ𝑖𝑔ℎ (36/132 (27.3%)) were more likely to respond to treatment with cidofovir (12/15 (80.0%)) than imiquimod (9/21 (42.9%)) (p= 0.026). Patients with HPV 16 L⁢1𝑙𝑜𝑤or HPV 16 E⁢2𝑙𝑜𝑤 (including those with no HPV/unassessable methylation) were more likely to respond to imiquimod: 23/50 (46.0%) vs 31/46 (67.4%) (p= 0.035). CONCLUSIONS: Combined HPV E⁢2 and L⁢1 methylation is a potential predictive marker in treatment for all patients with VIN. These findings justify validation in a prospective trial.