China-based CanSino Biologics (HKG: 6185) has announced positive periodical data from a clinical study assessing the safety and immunogenicity of its COVID-19 mRNA vaccine CS-2034 as a sequential booster in adults aged 18 and above who have already received three doses of inactivated COVID-19 vaccines. The study, which began in October 2022 and enrolled 433 subjects, is currently in the follow-up phase.
Study Design and Safety Analysis
The randomized, blind, parallel-controlled clinical study divided participants into two groups, with Group A further divided into two age groups: 18 to 59 years old and ≥ 60 years old (160 people each). Subjects were randomly inoculated with a dose of CS-2034 or COVID-19 inactivated vaccine at a ratio of 3:1, with 0.3 ml for the mRNA group and 0.5 ml for the inactivated vaccine group. All subjects underwent systematic safety observation within 28 days after vaccination and had samples collected on the day of vaccination, day 7, day 14, day 28, 3 months, and 6 months post-vaccination for immune evaluation. Group B consisted of 113 subjects (≥ 60 years old) who received one dose of CS-2034, with only safety observation conducted.
Safety analysis showed that the CS-2034 sequential booster has a good safety profile, with mainly mild adverse reactions. The incidence and severity of these reactions were significantly lower than those reported for other mRNA vaccines in the literature. The safety profile of the elderly subgroup was superior to that of the adult subgroup.
Immunogenicity Results
In terms of immunogenicity, neutralizing antibody test results showed that the geometric mean titers (GMT) of neutralizing antibodies against the prototype strain and Omicron BA.1 variant 28 days after CS-2034 were 877 and 293, respectively, 27 and 23 times higher than those achieved with the homologous booster of inactivated vaccine. A cross-neutralization antibody dynamics study against the currently popular Omicron BA.5 variant found that the antibody level peaked 7 days after immunization, with a GMT of 407, 29 times higher than the homologous booster of inactivated vaccine. CS-2034 also induced more neutralizing antibodies in the elderly subgroup aged 60 years and above, with a GMT for the Omicron BA.5 variant of 296, 23 times higher than the homologous booster of inactivated vaccine, 7 days post-inoculation.
Preclinical Findings and Future Outlook
Preclinical studies have shown that CS-2034, currently at Phase IIb stage, can induce high-titer neutralizing antibodies against a variety of important variants identified by the World Health Organization. Compared to vaccines based on the prototype strain, CS-2034 demonstrates broader-spectrum protection and is more effective against existing variants. The positive results from the clinical study highlight CanSino Biologics’ commitment to advancing innovative COVID-19 vaccines. With its demonstrated safety and immunogenicity, CS-2034 has the potential to significantly enhance protection against current and emerging SARS-CoV-2 variants.-Fineline Info & Tech
