“We are encouraged by the preliminary safety and immunogenicity profile of ReCOV in this FIH trial,” said Dr. Liu Yong, Chairman and General Manager. “Prophylactic vaccines are still the most effective means to prevent SARS-CoV-2 infection and control the global pandemic. We are looking forward to providing a next-generation of COVID-19 vaccine with the potential in safety, efficacy and accessibility, and will advance ReCOV into larger clinical studies soon to evaluate its efficacy and safety.”
This ongoing FIH trial is a randomized, double-blinded, placebo-controlled study to evaluate the safety, reactogenicity, and immunogenicity of 2 ascending doses of ReCOV, when administered as 2 intramuscular injections (with 21 days apart) in healthy subjects. Today Recbio reported partial unblinded data of safety, reactogenicity and immunogenicity for Cohort 1 (younger adults/ReCOV 20μg).
This cohort enrolled 25 participants who were 18 to 55 years of age. In the trial, the SARS-Cov-2-neutralizing antibody geometric mean titers (GMTs) were converted to WHO/NIBSC unit of IU/mL for comparisons of neutralizing antibody titers with those of other widely used vaccines. Recbio obtained GMTs of 1643.2 IU/mL for neutralizing antibodies at 14 days after two doses of ReCOV, with both seropositive rate (SPR) and seroconversion rate (SCR) as 100%, suggesting a promising efficacy of ReCOV in preventing SARS-COV-2 induced diseases. SARS-CoV-2 neutralizing antibodies were performed by central laboratory of the study (360Biolabs). According to a recent pre-print study1, the GMT of SARSCoV-2 neutralizing antibodies were 1404.16 IU/mL and 928.75 IU/mL 14 days after two doses for Moderna and BioNTech/Pfizer mRNA vaccines, respectively.
Notably, based on pooled human plasma from convalescent patients, WHO international standard (including 20/136, provided by National Institute for Biological Standards and Control [NIBSC]) was widely used to calibrate different diagnostic techniques.
Meanwhile, the cellular immunogenicity data showed that ReCOV could induce antigen-specific CD4+ T cell responses in younger adults, reflecting in IFN-γ and IL-2 production, an obvious trend toward Th1 phenotype was observed with a peak level of Th1 cytokines detected at Day 36 (14 days after the 2nd vaccination).
ReCOV was generally well tolerated with a good safety and tolerability profile. The majority of adverse events were mild in severity. No SAE or TEAE leading to early discontinuation, no abnormal vital signs/laboratory testing results with clinical significance.
Recbio developed three cutting-edge technology platforms for novel adjuvant development, protein engineering and immunological evaluation. Supported by these platforms, Recbio continue to discover and develop a full suite of innovative vaccine candidates, such as next-generation HPV, shingles and Flu vaccines.