Safety of AS04-HPV-16/18 vaccine in Chinese women aged 26 years and older and long-term protective effect in women vaccinated at age 18-25 years: A 10-year follow-up study

Introduction The pivotal efficacy study assessed efficacy and safety of GSK's AS04-HPV-16/18 vaccine in Chinese women aged 18-25 years up to 6 years. The present extension study, performed 4 years later, offered AS04-HPV-16/18 vaccination to placebo recipients. Vaccine safety and its long-term protective effect were assessed at Year 10. Methods All 6051 women who received AS04-HPV-16/18 or the placebo during the initial study (NCT00779766) were invited to phase III/IV, open-label, partially controlled extension Year 10 study (NCT03629886). Placebo recipients were offered three-dose AS04-HPV-16/18 vaccination and followed up over 12 months to assess the safety. Cervical samples from all women were examined. Vaccine efficacy (VE) against incident infections and cytological lesions associated with HPV-16/18 and other oncogenic types was assessed as exploratory objective. Results Among 3537 women (out of 6051) enrolled in the extension study, 1791 women (mean age 32.7 years; standard deviation 1.8 years) received AS04-HPV-16/18 and reported no serious adverse events, potential immune-mediated diseases, or adverse pregnancy outcomes related to vaccination. Among 6051 women, VE against incident HPV-16, -18, and -16/18 infections up to Year 10 was 82.8% (95% confidence interval: 72.5-89.7), 79.8% (64.5-89.2), and 80.8% (72.4-87.0), respectively. VE against HPV-16/18 ASC-US+, CIN1+, and CIN2+ was 92.7% (82.2-97.7), 94.8% (67.4-99.9), and 90.5% (34.6-99.8), respectively. Conclusion AS04-HPV-16/18 vaccine showed an acceptable safety profile in Chinese women vaccinated at age 26 years or above, and a long-term protection similar to other efficacy trials worldwide.