Inovio Pharmaceuticals on Tuesday reported interim Phase I data indicating that its experimental COVID-19 DNA vaccine candidate INO-4800 was "deemed safe and well-tolerated," through eight weeks. However, it did not disclose data about participants' antibody response. Company shares declined as much as nearly 18% on the news.
Stifel analyst Stephen Wiley remarked "we believe this preliminary data is likely to raise more questions on the competitive immunogenicity front, and limits our ability to get more-constructive on Inovio shares based on this limited disclosure alone." Meanwhile, H.C. Wainwright analyst Raghuram Selvaraju suggested Inovio's risk/reward balance "has increased significantly as many open questions remain," particularly in regards to the strength and duration of neutralising antibodies and T-cell responses.
The Phase I trial, which began in April, recruited 40 healthy adult volunteers in the US aged 18 to 50 years. Participants were enrolled into 1-mg and 2-mg dose cohorts, with each administered two doses of INO-4800 four weeks apart. Inovio said that all 10 reported adverse events were grade 1 in severity, and there were no serious side effects.
'Balanced' antibody, T-cell responses
The findings echo early safety results Inovio was hinting at in late May, when it also suggested that INO-4800 had induced neutralising antibodies and T-cell responses against SARS-CoV-2 in a preclinical study, sending shares up as much as nearly 23% at the time. On Tuesday, Inovio said analyses so far have shown that 94% of a total 36 trial participants demonstrated "overall immunological response rates based on preliminary data assessing humoral (binding and neutralising) and T-cell immune responses." Inovio said it plans to publish the full dataset in a peer-reviewed medical journal.
According to the company, the ability of its DNA vaccines to generate "balanced antibody and T-cell immune responses" could be important to developing potential COVID-19 vaccines. It pointed to recent scientific reports indicating that SARS-CoV-2-specific T cells found in convalescent patients have been "positively implicated in controlling the severity of their COVID-19 disease," while other studies have shown that 33% to 40% of convalescent individuals in their reports had "neutralising antibody below detectable levels."
Kate Broderick, senior vice president of R&D at Inovio, remarked "while the pathophysiologic profile of SARS-CoV-2 is not completely understood, research and clinical studies suggest that both T cell and antibody immune responses will be important for protection in both mild and serious infections." The company also reiterated that it plans to begin a Phase II/III efficacy study this summer in the US if regulators agree.
Selected for Warp Speed
Meanwhile, Inovio said INO-4800 has been selected to participate in a non-human primate challenge study as part of the US government's Operation Warp Speed. Last week, shares in Vaxart more than doubled after the company said its "tablet vaccine" candidate for COVID-19 was chosen to participate in a non-human primate challenge study as part of the US initiative. Other drugmakers taking part in Warp Speed, which aims to have substantial quantities of a safe and effective COVID-19 vaccine available for Americans by January 2021, include AstraZeneca, Johnson & Johnson, Merck & Co., Moderna and Pfizer.
"We look forward to…advancing INO-4800, as it is the only nucleic-acid based vaccine that is stable at room temperature for more than a year and does not require to be frozen in transport or for years of storage, which are important factors when implementing mass immunisations," commented Inovio CEO J. Joseph Kim.
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