Head-to-head immunogenicity comparison of an Escherichia coli-produced 9-valent human papillomavirus vaccine and Gardasil 9 in women aged 18-26 years in China: a randomised blinded clinical trial

Background An Escherichia coli-produced human papillomavirus (HPV) 16 and 18 bivalent vaccine (Cecolin) was prequalified by WHO in 2021. This study aimed to compare the immunogenicity of the E coli-produced HPV 9-valent vaccine Cecolin 9 (against HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58) with Gardasil 9.Methods This was a randomised, single-blind trial conducted in China. Healthy non-pregnant women aged 18-26 years, who were not breastfeeding and with no HPV vaccination history, were enrolled in the Ganyu Centre for Disease Control and Prevention (Lianyungang City, Jiangsu Province, China). Women were stratified by age (18-22 years and 23-26 years) and randomly assigned (1:1) using a permutated block size of eight to receive three doses of Cecolin 9 or Gardasil 9 at day 0, day 45, and month 6. All participants, as well as study personnel without access to the vaccines, were masked. Neutralising antibodies were measured by a triple-colour pseudovirion-based neutralisation assay. The primary outcomes, seroconversion rates and geometric mean concentrations (GMCs) at month 7, were analysed in the per-protocol set for immunogenicity (PPS-I). Non-inferiority was identified for the lower limit of the 95% CI of the GMC ratio (Cecolin 9 vs Gardasil 9) at a margin of 0 center dot 5 and a seroconversion rate difference (Cecolin 9-Gardasil 9) at a margin of -5%. This study was registered at ClinicalTrials.gov (NCT04782895) and is completed.Findings From March 14 to 18, 2021, a total of 553 potential participants were screened, of which 244 received at least one dose of Cecolin 9 and 243 received at least one dose of Gardasil 9. The seroconversion rates for all HPV types in both groups were 100% in the PPS-I, with the values of the lower limits of 95% CIs for seroconversion rate differences ranging between -1 center dot 8% and -1 center dot 7%. The GMC ratios of five types were higher than 1 center dot 0, with the highest ratio, for HPV 58, at 1 center dot 65 (95% CI 1 center dot 38-1 center dot 97), and those of four types were lower than 1 center dot 0, with the lowest ratio, for HPV 11, at 0 center dot 79 (0 center dot 68-0 center dot 93). The incidence of adverse reactions in both groups was similar (43% [104/244] vs 47% [115/243]).Interpretation Cecolin 9 induced non-inferior HPV type-specific immune responses compared with Gardasil 9 and is a potential candidate to accelerate the elimination of cervical cancer by allowing for global accessibility to 9-valent HPV vaccinations, especially in low-income and middle-income countries.