China-based Sinocelltech Group Ltd (SHA: 688520) has announced the preliminary interim analysis results of a Phase III clinical study for its in-house developed recombinant COVID-19 vaccines. The study evaluated the bivalent (Alpha + Beta variants) S trimer protein vaccine SCTV01C and the quadrivalent (Alpha + Beta + Delta + Omicron variants) S trimer protein vaccine SCTV01E. The results indicate that both vaccines are safe and effective in inducing a strong immune response.
Clinical Study Design and Results
The randomized, double-blind, positive vaccine-controlled Phase III study enrolled 1,800 healthy subjects. Among them, 1,350 subjects received 2-3 shots of inactivated vaccines, and 450 healthy subjects received 2-3 shots of mRNA vaccines. SCTV01E, SCTV01C, and a positive vaccine (either inactivated or mRNA vaccine) were randomly assigned to the groups in a 1:1:1 ratio. The results showed that one shot of SCTV01C or SCTV01E as a sequential booster was safe, with low incidence of local and systemic side effects, primarily mild 1-2 grade reactions. The safety profiles of SCTV01C, SCTV01E, and the inactivated vaccine control groups were highly similar.
On the 28th day after the booster shot, both SCTV01E and SCTV01C were able to induce the production of very high and high titers of antibodies against a variety of major variants. They could also induce the production of uniform, high-titer neutralizing antibodies regardless of the baseline titer. SCTV01E and SCTV01C demonstrated outstanding broad-spectrum cross-protection and the potential for efficient infection prevention against new variants that may emerge in the future.
Vaccine Development and Mechanism
SCTV01C and SCTV01E were designed to address the decreasing neutralizing antibody titers and protection rates observed with first-generation vaccines. SCTV01C contains two recombinant S-trimer protein antigens of Alpha and Beta, the main variants recognized by the WHO, and uses a new oil-in-water adjuvant that significantly enhances Th1 cells compared to traditional aluminum adjuvants. SCTV01E is an upgraded 4-valent modified vaccine based on SCTV01C, incorporating the emerging Delta and Omicron mutant S-trimer protein antigens.
Future Outlook
The positive interim results from the Phase III study underscore Sinocelltech’s progress in developing next-generation COVID-19 vaccines. By targeting multiple variants, SCTV01C and SCTV01E aim to provide broader protection and address the evolving nature of the SARS-CoV-2 virus.-Fineline Info & Tech
