Reactogenicity and immunogenicity of the newly developed purified chick embryo cell (PCEC)-rabies vaccine in man

A Randomized, Double-Blind, Controlled Phase III Clinical Trial to Evaluate the Immunogenicity and Safety of a Lyophilized Human Rabies Vaccine (Vero Cells) in Healthy Participants Aged 10-60 Years Following Essen and Zagreb Vaccination Procedures

OBJECTIVE

In this paper, we aim to show that the immunogenicity of the lyophilized human rabies vaccine (Vero cells) (investigational vaccine) developed by Dalian Aleph Biomedical Co., Ltd. in healthy participants aged 10-60 years old is non-inferior to the lyophilized PVRV (positive control) manufactured by Liaoning Chengda Biotechnology Co., Ltd. (Shenyang, China), and that its safety is clinically acceptable.

METHOD

A total of 2776 participants were enrolled in this study and divided into four groups: a five-dose test group, a five-dose control group, a four-dose test group, and a four-dose control group. The patients in the four-dose groups (Zagreb) were vaccinated on Days 0 (two doses), 7 (one dose), and 21 (one dose), and those in the five-dose groups (Essen) were vaccinated on Days 0, 3, 7, 14, and 28 (one dose each). The rabies-virus-neutralizing antibody assay with the RFFIT was used to assess the immunogenicity, and the adverse events (AEs) and serious adverse events (SAEs) were identified and collated.

RESULTS

The positive seroconversion rate was up to 100% on Days 14 and 35/42 after vaccination following any procedures in pre-immunization antibody-negative participants, and the positive seroconversion rate and geometric mean concentration (GMC) of the test groups (Zagreb and Essen vaccination procedures) was not inferior to that of the control groups. On Day 7 after vaccination, the immunogenicity of the Zagreb procedure with two doses of the vaccine on Day 0 was superior to the Essen procedure with one dose of vaccine, that is, the former had a higher seroconversion rate and RVNA titer. The non-inferiority criterion of immunogenicity was met for the whole population, the population aged 10-18 years and ≥18 years, and the pre-immunization antibody-positive population. The incidences of all AEs, solicited AEs, and unsolicited AEs in both groups were not statistically significant, and no vaccination-related SAEs were observed.

CONCLUSION

The investigated vaccine is safe, its immunogenicity is non-inferior to that of the control vaccine, and the efficacy of the Zagreb procedure is superior to that of the Essen procedure 7 days after the first dose.

Immunogenicity and safety of purified vero cell-cultured rabies vaccine under Zagreb 2-1-1 or 5-dose Essen regimen in the healthy Chinese subjects: a randomized, double-blind, positive controlled phase 3 clinical trial

Aim: The aims of the study were to evaluate the non-inferiority of the safety and immunogenicity of a new trial purified vero cell-cultured rabies vaccine (trial vaccine) in healthy subjects comparing with the control purified vero cell-cultured rabies vaccine (control vaccine) following Essen regimen and to evaluate the non-inferiority of the safety and immunogenicity of the trial vaccine following two intramuscular regimens, between Zagreb and Essen regimen. Methods: Serum samples were collected before vaccination and on d 7, 14, 35/42 post vaccination. Adverse events (AEs) were recorded for 30 d following each vaccination. This study was registered in the Chinese Clinical Trial Registry (ChiCTR-PPR-15007057). Results: There was no significant difference in the incidence of AEs, local and systemic reactions, among Zagreb group, Essen group, and control group. But the incidence of solicited AEs was a significant difference among the three groups (p = 0.0498). The incidence of solicited AEs was higher in Essen group than that in control group and Zagreb group (p = 0.0278, p = 0.0248). In the subjects whose antibodies were seronegative before vaccination, the seroconversion rates of antibodies among three groups were all 100.0% on d 14 and d 35/42. The Essen group was not inferior to the control group, and the Zagreb group was not inferior to the Essen group on d 14. On d 14 and d 35/42, the geometric mean concentration of the three groups was much higher than the immune protection level of 0.5 IU/ml. Conclusions: The trial vaccine had good safety and immunogenicity, and the trial vaccine is not inferior to the control vaccine. Abbreviations: PVRV: purified vero cell-cultured rabies vaccine; AE: adverse event; CI: confidence interval; GMC: geometric mean concentration; IM: intramuscular; NIFDC: National Institutes for Food and Drug Control; PPS: per-protocol set; SS: safety set; REFIT: Rapid Fluorescent Focus Inhibition Test; RVNA: rabies virus neutralizing antibody; WHO: World Health Organization.

A randomized open-labeled study to demonstrate the non-inferiority of purified chick-embryo cell rabies vaccine administered in the Zagreb regimen (2-1-1) compared with the Essen regimen in Chinese adults

The Zagreb regimen has been used for 20 years in various countries. In China, until 2010, the Zagreb schedule was only approved for purified chick embryo cell vaccine (PCECV) and purified Vero cell rabies vaccines (PVRV). In this phase III clinical trial, we aimed to demonstrate the safety and immunogenic non-inferiority of the Zagreb regimen compared with the Essen regimen in healthy adult Chinese immunized with PCECV (Rabipur®). The study enrolled 825 subjects aged 18 to 50 years; serum samples were collected on Days 0, 7, 14, 42, and at 13 months to assess rabies virus neutralizing antibody (RVNA) concentrations. Solicited and unsolicited local and systemic reactions were recorded for 6 days following the day of vaccination, and collected throughout the entire study period (Day 1 until Month 13). The Zagreb regimen was non-inferior to the Essen regimen with regard to RVNA concentrations after 7, 14, and 42 days, and 13 months of immunization. The non-inferiority of seroconversion was established at Days 14 and 42. The incidence of local and systemic reactions was similar between groups, and mostly of mild or moderate severity. Vaccine-related adverse events occurred more frequently in the Essen group than in the Zagreb group. Vaccination with PCECV under a 2-1-1 regimen is as safe and immunogenic as under the traditional 5-dose Essen regimen for rabies post-exposure prophylaxis, and is a more cost-effective option, has a more practical vaccination schedule, and can potentially increase compliance.

Immunogenicity and safety of purified chick-embryo cell rabies vaccine under Zagreb 2-1-1 or 5-dose Essen regimen in Chinese children 6 to 17 years old and adults over 50 years: a randomized open-label study

The aim of this Phase IIIb, open-label, randomized study was to demonstrate the non-inferiority of immune responses and to assess the safety of a purified chick-embryo cell rabies vaccine (PCECV) in healthy Chinese children (6 to 17 years) and older adults (≥51 years) following 2 alternative intramuscular (IM) simulated post-exposure prophylaxis (PEP) regimens: 4-dose Zagreb or 5-dose Essen regimen. Serum samples were collected prior to vaccination on Days 1 and 15 and on day 43 to assess immune response by rabies virus neutralizing antibody (RVNA) concentrations. Solicited adverse events (AEs) were recorded for up to 7 days following each vaccine dose, and unsolicited AEs throughout the entire study period. PCECV vaccination induced a strong immune response at Day 15, and the non-inferiority in immune response of the Zagreb vs. the Essen regimen was demonstrated in children and older adults. At Day 15,100% of children (N = 224), and 99% of subjects ≥51 years of age (N = 376) developed adequate RVNA concentrations (≥0.5 IU/mL); at Day 43 all subjects achieved RVNA concentrations ≥0.5 IU/mL, for both PEP regimens. The well-known tolerability and safety profile of the PCECV was again observed in this study following either Zagreb or Essen regimens. Rabies PEP vaccination with PCECV following a Zagreb regimen induced immune responses non-inferior to those of the Essen regimen, and had a similar safety and tolerability profile to the Essen regimen in Chinese children, adolescents, and adults over 51 years. ClinicalTrials.gov identifier: NCT01680016.