Safety and immunogenicity of a pichia pastoris-expressed bivalent human papillomavirus (types 16 and 18) L1 virus-like particle vaccine in healthy Chinese women aged 9-45 years: A randomized, double-blind, placebo-controlled phase 1 clinical trial

Safety, Tolerability, and Immunogenicity of a Recombinant Nonavalent Human Papillomavirus Vaccine (Escherichia coli) in Healthy Chinese Women Aged 18-45 Years: A Phase 1 Clinical Trial

BACKGROUND

Prophylactic human papillomavirus (HPV) vaccination substantially alleviates cervical cancer burden. This study aimed to evaluate the safety, tolerability, and immunogenicity of an Escherichia coli-expressed recombinant nonavalent HPV vaccine.

METHODS

A dose-escalating phase 1 clinical trial was conducted in Sheyang County, Jiangsu Province, China. Each participant received either the test vaccine or the control vaccine (Gardasil 9) following a 0/2/6-month schedule. Adverse reactions (ARs) within 7 days after vaccination, adverse events (AEs) within 30 days, and serious adverse events (SAEs) throughout the study were recorded. Blood parameters were measured before and 3 days after each dose. Serum immunoglobulin G (IgG) and neutralizing antibodies (nAbs) against nine HPV types were analyzed at months 0, 3, and 7.

RESULTS

A total of 160 women aged 18-45 years were enrolled, and 155 participants completed the full vaccination regimen. Within 7 days following vaccination, the incidence of ARs ranged from 56.67% to 90.00%, with the low-dose group showing a significantly higher rate than the control group (p = 0.004). Most AEs were mild or moderate, and no vaccine-related SAEs occurred. No significant differences were observed among the four groups regarding the incidence of abnormal laboratory findings. Seroconversion rates for nAbs and IgG against nine HPV types exceeded 97.92% following three doses. High levels of nAbs and IgG were observed at months 3 and 7, with geometric mean titers (GMTs) showing further increases by month 7.

CONCLUSIONS

This new recombinant nonavalent HPV vaccine exhibits good tolerability and strong immunogenicity among women aged 18-45 years, supporting further efficacy studies in larger populations.

Development of a chemiluminescence enzyme immunoassay (CLEIA) for quantitating L1 protein in HPV vaccines

The L1 protein serves as the principal capsid component of human papillomavirus (HPV). All globally commercialized HPV vaccines utilize virus-like particles (VLPs) formed through L1 protein self-assembly. Quantitative analysis of L1 protein concentration constitutes a critical parameter for evaluating the antigenic potency of HPV vaccines. In this study, we developed a chemiluminescent enzyme immunoassay (CLEIA) for precise quantification of L1 protein in bivalent HPV vaccines. Employing a sandwich immunoassay format, antigen-antibody complexes were immobilized on 96-well microplates using capture antibodies, followed by detection with HRP-conjugated secondary antibodies. Chemiluminescent signal amplification was achieved through enzymatic catalysis of luminol/hydrogen peroxide in the presence of enhancer molecules. Systematic optimization of experimental parameters yielded a validated methodology demonstrating excellent reproducibility (inter-assay CV < 4 %), accuracy (recovery rate 100.5 ± 2.8 % for 16L1 and 95.5 ± 6.4 % for 18L1), precision (inter-assay CV < 7 %) and sensitivity (limit of quantitation (LOQ) 0.0996 μg/mL for HPV16L1 and 0.1459 μg/mL for HPV18L1). This optimized assay provides a reliable analytical platform for quantitating L1 Protein in bivalent HPV vaccine.

Roles of human papillomavirus in cancers: oncogenic mechanisms and clinical use

Human papillomaviruses, particularly high-risk human papillomaviruses, have been universally considered to be associated with the oncogenesis and progression of various cancers. The genome of human papillomaviruses is circular, double-stranded DNA that encodes early and late proteins. Each of the proteins is of crucial significance in infecting the epithelium of host cells persistently and supporting viral genome integrating into host cells. Notably, E6 and E7 proteins, classified as oncoproteins, trigger the incidence of cancers by fostering cell proliferation, hindering apoptosis, evading immune surveillance, promoting cell invasion, and disrupting the balance of cellular metabolism. Therefore, targeting human papillomaviruses and decoding molecular mechanisms by which human papillomaviruses drive carcinogenesis are of great necessity to better treat human papillomaviruses-related cancers. Human papillomaviruses have been applied clinically to different facets of human papillomavirus-related cancers, including prevention, screening, diagnosis, treatment, and prognosis. Several types of prophylactic vaccines have been publicly utilized worldwide and have greatly decreased the occurrence of human papillomavirus-related cancers, which have benefited numerous people. Although various therapeutic vaccines have been developed and tested clinically, none of them have been officially approved to date. Enhancing the efficacy of vaccines and searching for innovative technologies targeting human papillomaviruses remain critical challenges that warrant continuous research and attention in the future.

Opportunities and challenges for human papillomavirus vaccination in China

Current estimates of the HPV infection rate in China vary by geographic region (9.6-23.6%), with two age peaks in prevalence in women ≤20-25 years of age and 50-60 years of age. HPV-16, 52 and 58 are the most commonly-detected HPV genotypes in the Chinese population. In China, five HPV vaccines are licensed and several others are undergoing clinical trials. Multiple RCTs have shown the efficacy and safety of the bvHPV (Cervarix), Escherichia coli-produced bvHPV (Cecolin), Pichia pastoris-produced bvHPV (Walrinvax), qvHPV (Gardasil) and 9vHPV (Gardasil-9) vaccines in Chinese populations, including two studies showing long-term efficacy (≥8 years) for the bvHPV and qvHPV vaccines. Real-world data from China are scarce. Although modeling studies in China show HPV vaccination is cost-effective, uptake and population coverage are relatively low. Various policies have been implemented to raise awareness and increase vaccine coverage, with the long-term aim of eliminating cervical cancer in China.

A Preclinical Immunogenicity Study of the Recombinant Human Papillomavirus Nine-Valent Virus-like Particle Vaccine

BACKGROUND

Cervical cancer is associated with persistent infection of high-risk human papillomaviruses (HPVs). Prophylactic HPV vaccines have been recommended and have significant efficacy in preventing cervical cancer. Multivalent HPV vaccines have a better preventative effect on HPV-related diseases. However, there is currently only one nine-valent HPV vaccine on the market: Gardasil® 9. The development of new HPV vaccines is still urgent in order to achieve the goal of eliminating cervical cancer as proposed by the WHO.

METHODS

In this study, we developed a nine-valent recombinant HPV virus-like particle (VLP) vaccine (HPV-9 vaccine) containing HPV type 6, 11, 16, 18, 31, 33, 45, 52, and 58 antigens, with an adjuvant of aluminum phosphate (AlPO4). The type-specific L1 proteins were recombinantly expressed using Pichia pastoris, followed by self-assembly into VLPs. Immunogenicity studies of the HPV-9 vaccine were performed using rodents (mice and rats) and non-human primates (macaques) as animal models.

RESULTS

Immunogenicity studies showed that the HPV-9 vaccine is able to elicit a robust and long-lasting neutralizing antibody response in rodents (mice and rats) and non-human primates (cynomolgus macaque) models. The HPV-9 vaccine shows immunogenicity comparable to that of Walrinvax® and Gardasil® 9.

CONCLUSIONS

In summary, this study provides a comprehensive investigation of the immunogenicity of the HPV-9 vaccine, including its immune persistence. These findings, derived from using models of diverse animal species, contribute valuable insights into the potential efficacy of the vaccine candidate in clinical settings.

Comparison of the safety and persistence of immunogenicity of bivalent HPV16/18 vaccine in healthy 9-14-year-old and 18-26-year-old Chinese females: A randomized, double-blind, non-inferiority clinical trial

BACKGROUND

We assessed the safety, immunogenicity and antibody persistence of two- and three-dose schedules of the novel bivalent HPV16/18 vaccine (HPV-2, Walrinvax) in the per-protocol target population of initially seronegative 9-14 year-old girls, including a non-inferiority comparison with the three-dose schedule in 18-26 year-old women.

METHODS

This randomized phase 3b trial in Guangxi Zhuang Autonomous Region, China, involved healthy Chinese females in two age cohorts; 600 girls aged 9-14 years and 300 women aged 18-26 years. Girls were randomly assigned (1:1) to receive either two (Months 0,6) or three (Months 0,2,6) intramuscular doses of HPV-2. All participants were monitored for immunogenicity as neutralizing antibodies up to 36 months. Primary objectives were non-inferiority analyses of immunogenicity between two- and three-dose girl groups and adult women at Month 7; safety assessments were based on participant-completed diary cards.

RESULTS

All groups demonstrated marked increases in neutralizing antibodies against HPV 16 and 18 that persisted above baseline to 36 months. Month 7 responses in both girl groups were non-inferior to those in the women and were statistically higher after two-doses than girls or women who received three doses. GMTs waned after month 7, but then maintained a plateau level until month 36. Vaccination was well tolerated in all groups with no serious adverse events reported.

CONCLUSIONS

Immune responses to two doses of HPV-2 vaccine in adolescent girls were non-inferior to those after three doses in young women, an age cohort in which clinical efficacy of HPV-2 against cervical cancer has been demonstrated.