Recurrence of vulval intraepithelial neoplasia following treatment with cidofovir or imiquimod: results from a multicentre, randomised, phase II trial (RT3VIN)

OBJECTIVE: To compare the recurrence rates after complete response to topical treatment with either cidofovir or imiquimod for vulval intraepithelial neoplasia (VIN) 3. DESIGN: A prospective, open, randomised multicentre trial. SETTING: 32 general hospitals located in Wales and England. POPULATION OR SAMPLE: 180 patients were randomised consecutively between 21 October 2009 and 11 January 2013, 89 to cidofoovir (of whom 41 completely responded to treatment) and 91 to imiquimod (of whom 42 completely responded to treatment). METHODS: After 24 weeks of treatment, complete responders were followed up at 6‐monthly intervals for 24 months. At each visit, the Common Terminology Criteria for Adverse Events (CTCAE) v3.0 was assessed and any new lesions were biopsied for histology. MAIN OUTCOME MEASURES: Time to histologically confirmed disease recurrence (any grade of VIN). RESULTS: The median length of follow up was 18.4 months. At 18 months, more participants were VIN‐free in the cidofovir arm: 94% (95% CI 78.2–98.5) versus 71.6% (95% CI 52.0–84.3) [univariable hazard ratio (HR) 3.46, 95% CI 0.95–12.60, P = 0.059; multivariable HR 3.53, 95% CI 0.96–12.98, P = 0.057). The number of grade 2+ events was similar between treatment arms (imiquimod: 24/42 (57%) versus cidofovir: 27/41 (66%), χ2 = 0.665, P = 0.415), with no grade 4+. CONCLUSIONS: Long‐term data indicates a trend towards response being maintained for longer following treatment with cidofovir than with imiquimod, with similar low rates of adverse events for each drug. Adverse event rates indicated acceptable safety of both drugs TWEETABLE ABSTRACT: Long‐term follow up in the RT3VIN trial suggests cidofovir may maintain response for longer than imiquimod.