- Pennsylvania biotech Inovio on Tuesday disclosed preliminary study results for its experimental coronavirus vaccine, announcing that 94% of healthy volunteers treated in its Phase 1 trial showed an "overall immunological response" to the shot.
- The company did not detail, however, what levels of antibody or immune cell response were reached, nor did it offer comparisons to responses observed in patients who've recovered from infection with the SARS-CoV-2 virus, making its claims difficult to assess.
- Inovio said its vaccine, dubbed INO-4800, would be included in preclinical studies as part of the U.S. government's "Operation Warp Speed," which could help assess its effectiveness relative to other vaccines now in development. Involvement doesn't guarantee, however, that Inovio's candidate will be among the roughly seven vaccines that the U.S. plans to select for prioritized trial and manufacturing support.
Inovio's vaccine was one of the first to be studied in humans, trailing front-runner Moderna and China's CanSino Biologics in entering clinical testing earlier this year.
It's also the most advanced candidate in a class of vaccines that use small DNA molecules called plasmids to instruct the body's cells to build proteins mimicking those found on SARS-CoV-2.
In releasing initial results Tuesday, Inovio joins a small group of companies that have shared initial findings from their clinical studies. Moderna and CanSino have both revealed results, although CanSino beat Moderna to publishing its data in a peer-reviewed journal.
China's Sinovac and Sinopharm have also made brief disclosures about their vaccines' early progress.
A Phase 1 trial is primarily designed to assess whether a vaccine is safe, and Inovio stated that there were no severe side effects. The 10 adverse reactions observed in the study were the lowest severity, mostly reactions to the vaccine injection.
However, with national leaders urgently seeking a vaccine to bring the coronavirus pandemic under control, preliminary signs of efficacy might be used to justify government funding or accelerated regulatory review, as the U.S. is trying to do with Operation Warp Speed.
On that front, Inovio provided less details on INO-4800's effectiveness than did Moderna with its candidate. According to Inovio, 34 of 36 trial participants demonstrated a response to inoculation, based on " preliminary data assessing humoral (binding and neutralizing) and T cell immune responses."
By contrast, Moderna compared the antibody responses triggered by its vaccine to those seen in the blood of patients who have recovered from an infection of the coronavirus. CanSino, in publishing its data, also chose not to make such a comparison, arguing that "correlates of protection for a vaccine against COVID-19 are unknown."
Charles Duncan, an analyst at Cantor Fitzgerald, took the same position in evaluating Inovio's statement Tuesday, writing in a note to clients that "the comparison has clear limitations."
Stifel analyst Stephen Willey, on the other hand, was more cautious. He wrote in an investor note that Inovio executives told him an immune response meant the vaccine stimulated either binding antibodies, the more potent neutralizing antibodies or T cells, but not necessarily all three together.
Fuller disclosure of immune responses "represents important information we'll need to appropriately assess the competitive relevance of this data," Willey wrote.
Inovio said it plans to publish its data in a peer-reviewed medical journal.
Shares in Inovio fell 10% Tuesday following release of its data, a notable drop after days of steady stock gains for the company.
Convincing people of its vaccine's promise is only one of the challenges facing Inovio. The company's ability to quickly scale up manufacturing — a critical test for vaccine makers — has been slowed by a legal battle with its DNA plasmid supplier VGXI.
Last week, a court ruled against an emergency injunction that might have helped Inovio transfer technology to two other manufacturers, Richter-Helm BioLogics and Ology Bioservices.