Inovio Pharmaceuticals (NASDAQ: INO) has announced the results of pre-clinical testing of their DNA-based COVID-19 vaccine candidate INO-4800 in animal models. The data, published in the journal Nature Communications in an article titled “Neutralizing Antibody and T Cell Immune Responses in Preclinical Models,” showed that INO-4800 induced the “robust” expression of SARS-CoV-2 binding and neutralizing antibodies and anti-viral T cell responses in mice and guinea pigs.
Anti-SARS-CoV-2 binding antibodies were also detected in the lungs of the animals, suggesting that the vaccine could protect against infection in the lungs and the respiratory illness characteristic of severe cases of COVID-19. According to the authors, T cell responses against the virus were observed “as early as day 7 post-vaccine delivery.”
While guinea pigs evaluated in the study developed anti-SARS-CoV-2 antibodies after receiving a single dose of the vaccine, whether humans will require more than one dose remains to be determined.
According to Inovio, “Importantly, the authors demonstrated virus neutralizing activity using three separate neutralization assays testing the vaccine’s ability to generate antibodies which can block virus infection by: 1) an assay using live SARS-CoV-2 viruses; 2) an assay using a pseudo-virus assay, where another virus displays the SARS-CoV-2 Spike protein; and, 3) a novel high-throughput surrogate neutralization assay measuring the ability of INO-4800-induced antibodies to block SARS-CoV-2 Spike binding to the host ACE2 receptor.”
“Study authors also detected these antibodies in the lungs of the vaccinated animals which could be important in providing protection from SARS-CoV-2. In addition, high levels of Spike-specific T cell responses were observed with INO-4800 vaccination, which could be important in mediating protection from the virus infection. Collectively, this preclinical dataset demonstrates that INO-4800 is a promising COVID-19 vaccine candidate against this emerging disease threat.”
The stability of Inovio’s DNA vaccine could support its dissemination and stockpiling during the pandemic. According to the authors, the vaccine does not require freezing during storage and transport, and can be stored at 2–8 °C for at least 4.5 years, room temperature for 1 year, and at 37 °C for 1 month, while “maintaining potency at temperatures upwards of 60 °C.”
The authors concluded that their “initial results describing the immunogenicity of COVID-19 vaccine candidate INO-4800 are promising” and that their study “supports the further evaluation of INO-4800 as a vaccine candidate for COVID-19.”
Senior Vice President of Research and Development and the Team Lead for COVID-19 vaccine development at Inovio Dr. Kate Broderick stated, “These positive preclinical results from our COVID-19 DNA vaccine (INO-4800) not only highlight the potency of our DNA medicines platform, but also build on our previously reported positive Phase 1/2a data from our vaccine against the coronavirus that causes MERS, which demonstrated near-100% seroconversion and neutralization from a similarly designed vaccine INO-4700.”
“The potent neutralizing antibody and T cell immune responses generated in multiple animal models are supportive of our currently on-going INO-4800 clinical trials,” Dr. Broderick continued.
President and CEO of Inovio Dr. J Joseph Kim stated, “INOVIO and our collaborators are working diligently to advance INO-4800 to help fight the current pandemic. We are planning to utilize these positive preclinical results along with our upcoming animal challenge data and safety and immune responses data from our Phase 1 studies to support rapidly advancing this summer to a large, randomized Phase 2/3 clinical trial.”
INO-4800 is composed of DNA plasmids encoding the spike (S) protein of the SARS-CoV-2 virus, a structural element important for the transmission of the virus into human host cells. Neutralizing antibody targeting epitopes on the spike protein can effectively prevent infection by the coronavirus, and was identified in animal models addressed in the Nature Communications publication, according to Inovio.
The vaccine is administered using Inovio’s proprietary CELLECTRA® device, which uses a “brief electrical pulse” to deliver DNA plasmids “directly into cells intradermally or intramuscularly.”
Inovio anticipates that preliminary data on the safety and immunogenicity of INO-4800 from the phase 1 trial will be available in June, and intends to initiate a phase 2/3 efficacy trial in July or August “pending regulatory approval.” Data from multiple animal challenge studies is “expected in coming weeks and will complement the data from animal models published in the Nature Communications paper.
COVID-19 vaccines are also under development by Moderna, iBio, Heat Biologics, Dynavax, and Novavax, among other companies. Gilead Sciences has evaluated a potential inhibitor of the SARS-CoV-2 coronavirus, Remdesivir, in phase 3 clinical trials. Biocryst Pharmaceuticals is evaluating the efficacy of anti-viral drug Galidesivir for treating COVID-19 in a phase 1 clinical trial. Vir Biotechnology is developing a neutralizing antibody against the virus.