Authors:
Kreimer AR, Struyf F, Del Rosario-Raymundo MR, Hildesheim A, Skinner SR, Wacholder S, et al.
Authors notes:
Lancet Oncol. 2015;16(7):775-86.
Keywords:
Cervical cancer, Human papillomavirus, HPV-16, HPV-18, vaccine
Abstract:
Background: There is some evidence to suggest that one or two doses of the HPV vaccine provides similar protection to the three-dose regimen.
The main aim of the study was to ascertain HPV-16/18 vaccine efficacy in both full and naive cohorts and to explore protection conferred against non-vaccine HPV types, by number of doses received.
Methods: Summary data from the Costa Rica Vaccine Trial and ~the PATRICIA trial, two phase 3, double-blind, randomised controlled clinical trials of the HPV-16/18 AS04-adjuvanted vaccine in young women, were combined in a post-hoc analysis to investigate the efficacy of fewer than three doses of the HPV-16/18 vaccine after 4 years of follow-up.
Women were randomly assigned to receive three doses of the HPV-16/18 vaccine or to a control vaccine; yet, some received fewer doses.
After exclusion of women with less than 12 months of follow-up or those who were HPV-16/18 DNA-positive at enrolment (for the HPV-16/18 endpoint), we calculated vaccine efficacy against one-time detection of incident HPV infections after three, two, and one dose(s).
The primary study endpoint was one-time detection of first incident HPV-16/18 infections accumulated during the follow-up phase. F
Findings: We assessed vaccine efficacy against incident HPV-16/18 infection in the modified total vaccinated cohort (22 327 received three doses, 1185 two doses, 543 one dose).
Vaccine efficacy against incident HPV-16/18 infections for three doses was 77·0%, two doses was 76·0%, and one dose was 85·7%.
Vaccine efficacy against incident HPV-31/33/45 infections for three doses was 59·7%, two doses was 37·7%, and one dose was 36·6%.
Vaccine efficacy against incident HPV-16/18 infection for two-dose women who received their second dose at 1 month was 75·3% and 82·6% for those who received the second dose at 6 months (CVT data only).
Vaccine efficacy against HPV-31/33/45 for two-dose women who received their second dose at 6 months, but not those receiving it at one month, was similar to the three-dose group.
Interpretation: 4 years after vaccination of women aged 15-25 years, one and two doses of the HPV-16/18 vaccine seem to protect against cervical HPV-16/18 infections, similar to the protection provided by the three-dose schedule.
Two doses separated by 6 months additionally provided some cross-protection. These data argue for a direct assessment of one-dose efficacy of the HPV-16/18 vaccine.
Funding: US National Cancer Institute, National Institutes of Health Office of Research on Women's Health, and Ministry of Health of Costa Rica (CVT); GlaxoSmithKline Biologicals SA (PATRICIA).