In a 10-year, follow-up study in patients vaccinated with Gardasil 9, no cases of HPV-related cancers or genital warts were seen.
Results of a phase 3 trial of Gardasil 9 (human papillomavirus 9-valent vaccine, recombinant) in patients aged 9 to 15 years old, have been published in the journal Pediatrics.1
Gardasil 9 is a vaccine developed to prevent cancers caused by multiple human papillomavirus (HPV) types in people aged 9 to 45 years. These include cervical, vulvar, vaginal, anal, oropharyngeal, and neck and head cancers, as well as vaginal, vulvar, cervical, and anal lesions.
According to the Centers for Disease Control and Prevention, tens of thousands of HPV-related cancer diagnoses were given per year from 2015 to 2019. Cervical cancer is the only HPV-related cancer to have routinely recommended screening, with no method available to determine which patients with HPV will develop further health problems.
Investigators conducted a phase 3 trial, which turned into a 10-year long-term follow-up (LTFU) to evaluate the immunogenicity in Gardasil 9 in male and female patients aged 9 to 15 years through 10 years after the last dose of Gardasil 9.
Secondary outcomes included long-term incidence and disease of infections caused by HPV 6, 11, 16, 18, 31, 33, 45, 52 and 58. Safety data included deaths and vaccine-related serious adverse events.
There were 1,272 participants in the LTFU study, 971 of which were girls and 301 boys. Of these, 872 girls and 262 boys were included in the per-protocol population,
Patients in the per-protocol population, “completed the Gardasil 9 vaccination series within 1 year, were seronegative to the relevant HPV type at initiation of the vaccination series and had not initiated sexual activity prior to receiving the third dose of GARDASIL 9.”
HPV-antibody responses at 10 years following the third dose were sustained in male and female participants, with 99.6% to 100% of participants being seropositive for the targeted HPV types at month 7 and 81.3% to 97.7% being seropositive at month 126 depending on HPV type. This indicated peak geometric mean titers at month 7.
When evaluating secondary outcomes, investigators did not find cases of vaccine-targeted HPV type high-grade disease in female patients. However, 1 CIN1 case tested positive for HPV 16, 39, and 59 at month 84.
“HPV-related cancers and diseases are a significant public health issue,” Eliav Barr, MD. senior vice president, head of global clinical development and chief medical officer at Merck Research Laboratories said in a press release. “These strong study results serve as a reminder that we need to do everything we can to expand and recover vaccination rates globally to help protect all eligible people from certain HPV-related cancers.”
1. Long-term follow-up data on sustained immunogenicity and safety for GARDASIL®9 published in Pediatrics. Merck. September 5, 2023. Accessed September 5, 2023. https://www.merck.com/news/long-term-follow-up-data-on-sustained-immunogenicity-and-safety-for-gardasil9-published-in-pediatrics/