Potency, toxicity and protection evaluation of PastoCoAd candidate vaccines: Novel preclinical mix and match rAd5 S, rAd5 RBD-N and SOBERANA dimeric-RBD protein.

Despite substantial efforts, no effective treatment has been discovered for severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. Therefore, vaccination to reach herd immunity is the ultimate solution to control the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to evaluate the potency, toxicity, and protection of candidate PastoCoAd vaccines as novel mix and match of recombinant adenovirus type 5 (rAd5) containing the full-length spike protein (rAd5-S), rAd5 containing the receptor-binding domain of S protein and nucleoprotein (rAd5 RBD-N), and SOBERANA dimeric RBD protein of SARS-CoV-2. Three vaccine candidates were developed against SARS-CoV-2 using adenoviral vectors, including the prime-boost (rAd5-S/rAd5 RBD-N), heterologous prime-boost (rAd5-S/ SOBERANA vaccine), and prime only (mixture of rAd5-S and rAd5 RBD-N). The rAd5-S and rAd5 RBD-N were produced with a Cytomegalovirus promoter and the human tissue plasminogen activator (tPA) leader sequence. The immunogenicity of vaccine candidates was also evaluated in mouse, rabbit, and hamster models and protection was evaluated in a hamster model. Following the injection of vaccine candidates, no significant toxicity was observed in the tissues of animal models. The immunogenicity studies of mice, rabbits, and hamsters showed that responses of total IgG antibodies were significantly higher with the prime-only and heterologous prime-boost vaccines as compared to the other groups (P < 0.009). Virus neutralizing antibodies were detected, and the level of cytokines related to humoral and cellular immunity increased significantly in all vaccinated models. A high cellular immunity response was found in the vaccinated groups compared to the controls. On the other hand, the vaccine challenge test showed that the virus titers significantly decreased in the pharynx and lung tissues of vaccinated hamsters compared to the control group. These successful findings suggest the safety and protection produced by the heterologous prime-boost vaccine (adenovector/ SOBERANA RBD), as well as a single dose of adenovector vaccine in animal models.

Open label phase I/II clinical trial and predicted efficacy of SARS-CoV-2 RBD protein vaccines SOBERANA 02 and SOBERANA Plus in children

ObjectivesTo evaluate heterologous vaccination scheme in children 3-18 y/o combining two SARS-CoV-2 r-RBD protein vaccines. MethodsA phase I/II open-label, adaptive and multicenter trial evaluated the safety and immunogenicity of two doses of SOBERANA02 and a heterologous third dose of SOBERANA Plus in 350 children 3-18 y/o in Havana Cuba. Primary outcomes were safety (in phase I) and safety/immunogenicity (in phase II) measured by anti-RBD IgG ELISA, molecular and live-virus neutralization titers and specific T-cells response. A comparison with adult s immunogenicity and prediction of efficacy were done based on immunological results ResultsLocal pain was the unique adverse event with frequency >10%, none was serious or severe. Two doses of SOBERANA 02 elicited humoral immune response similar to natural infection; the third dose increased significantly the response in all children, similar to that achieved in vaccinated young adults and higher than in convalescents children. The neutralizing titer was evaluated in a participant s subset: GMT was 173.8 (CI 95% 131.7; 229.5) vs. alpha, 142 (CI 95% 101.3; 198.9) vs. delta and 24.8 (CI 95% 16.8; 36.6) vs. beta. An efficacy > 90% was estimated. ConclusionThe heterologous scheme was safe and immunogenic in children 3-18 y/o. Trial registry: https://rpcec.sld.cu/trials/RPCEC00000374

Safety and immunogenicity of anti-SARS CoV-2 conjugate vaccine SOBERANA 02 in a two-dose or three-dose heterologous scheme in adults: Phase IIb Clinical Trial

BackgroundWe report results of immunogenicity, safety and reactogenicity of SOBERANA 02 in a two-dose or three-dose heterologous scheme in adults in a phase IIb clinical trial. MethodThis phase IIb trial was designed as parallel, multicentre, adaptive, double blind, randomized and placebo-controlled. Subjects (N=810) aged 19-80 years were randomized to receive two doses of the recombinant SARS CoV-2 receptor binding domain (RBD) conjugated to tetanus toxoid (SOBERANA 02) and a third dose of dimeric RBD (SOBERANA Plus) 28 days apart; two production batches of active ingredient of SOBERANA 02 were evaluated. Primary outcome was the percentage of seroconverted subjects with [≥]4-fold the anti-RBD IgG concentration. Secondary outcomes were safety, reactogenicity and neutralizing antibodies. ResultsSeroconversion rate in vaccinees was respectively 76.3 and 96.8% after two or three doses, compared with 7.3% in placebo group. Anti-RBD IgG increased significantly after first and second dose of SOBERANA 02 respect to placebo group; and the third dose with SOBERANA Plus boosts the response compared to the second dose. Neutralizing IgG antibodies were detected against D614G and VOCs , {beta} and {delta}. Specific and functional antibodies were detected at least until 7-8 months after the third dose. The frequency of serious adverse events (AEs) associated with vaccination was very low (0.1%); with only one serious AE consistent with vaccination. Local pain was the most frequent AE. ConclusionsTwo doses of SOBERANA 02 were well tolerated, safe an immunogenic in adults aged 19-80 years old. The heterologous combination with a third dose of SOBERANA Plus increased neutralizing antibodies, detectable 7-8 months after finishing the vaccination schedule. Trial registryhttps://rpcec.sld.cu/trials/RPCEC00000347

Efficacy and Safety of SOBERANA 02, a COVID-19 conjugate vaccine in heterologous three doses combination

BackgroundSOBERANA-02 is a COVID-19 conjugate vaccine (recombinant RBD conjugated to tetanus toxoid). Phases 1/2 clinical trials demonstrated high immunogenicity, promoting neutralizing IgG and specific T-cell response. A third heterologous dose of SOBERANA-Plus (RBD-dimer) further increased neutralizing antibodies. MethodsFrom March 8th to September 30th, 2021 we conducted in Havana, Cuba a multicentre randomized, double-blind, placebo-controlled, phase-3 trial evaluating two doses of SOBERANA-02 and a heterologous scheme with one dose SOBERANA-Plus added to it. Participants 19-80 years were randomly assigned to receiving 28 days apart either the two or three dose scheme or placebo. The main endpoint was vaccine efficacy in preventing the occurrence of RT-PCR confirmed symptomatic COVID-19 occurring at least 14 days after the second or third dose in the per-protocol population. We also assessed efficacy against severe disease and, in all participants receiving at least one vaccine/placebo dose, safety for 28 days after each dose. FindingWe included 44{middle dot}031 participants in a context of Beta VOC predominance, with this variant being gradually replaced by Delta near the trial end. Vaccine efficacy in the heterologous combination was 92{middle dot}0% (95%CI 80{middle dot}4-96{middle dot}7) against symptomatic and 100% against severe COVID-19. Two doses of SOBERANA-02 was 69{middle dot}7% (95%CI 56{middle dot}5-78{middle dot}9) and 74{middle dot}9% (95%CI 33{middle dot}7-90{middle dot}5) efficacious to protect against symptomatic and severe COVID-19, respectively. The occurrence of serious and severe AEs was very rare and equally distributed between placebo and vaccine groups. Solicited AEs were slightly more frequent in the vaccine group but predominantly local and mostly mild and transient. InterpretationOur results indicate that the straightforward to manufacture SOBERANA vaccines are efficacious in a context of Beta and Delta VOC dominance and that they constitute an attractive, feasible option for low- and middle-income countries, where besides financial constraints ease of vaccine storage and distribution is of concern. FundingThis study received funds from Finlay Vaccine Institute and National Fund for Science and Technology (FONCI-CITMA-Cuba, contract 2020-20). of Ministry of Science, Technology and the Environment (Contract Project-2020-20) in Cuba.