Inovio on Tuesday announced “positive” results from early-stage testing of its COVID-19 vaccine, but did not disclose complete data, and the news won a frosty reception on Wall Street.

In a news release, the Plymouth Meeting-based company said that six weeks after two injections, 34 out of 36 clinical trial participants, or 94%, “demonstrated overall immunological response rates based on preliminary data.” Both antibodies and T-cell immune responses were assessed.

Shares of Inovio stock, which have soared in value this year, closed down almost 15%, to $26.95, in Tuesday trading.


Inovio has been considered a front-runner in the race to develop a vaccine for the coronavirus. However, its technology platform, based on synthetic DNA, has never yielded an approved vaccine. The technology was pioneered 30 years ago by David Weiner, who co-founded the company and is now a scientific adviser.

Inovio’s statement said the vaccine was “generally safe and well-tolerated.” Adverse events were mild, mostly redness at the injection site.

Inovio president and CEO J. Joseph Kim dismissed the decline in the stock price and said the developers are focused on the public-health emergency.

“We don’t pay a whole lot of attention to short-term stock movements,” Kim said in an interview. “This is really good data. We’re excited. It’s safe and very immunogenic and we look forward to advancing it.”

Inovio’s trial, which started in April, initially had 40 participants, but three were excluded because they tested positive for COVID-19 and another left the study for non-clinical reasons. Inovio said it will publish the “full data set” in a medical journal.

Inovio plans to expand into later-stage testing this summer. The company is collaborating with the Wistar Institute, where Weiner is vice president, and has received funding from the federal government, foundations, and other sources.

The company suffered a setback last week when a Montgomery County Common Pleas Court judge rejected Inovio’s move to force its contract manufacturer to share proprietary technology with other suppliers.

Inovio argued that Houston-based VGXI is already at manufacturing capacity and is an obstacle to Inovio’s goal of being able to make one million doses of its vaccine by year’s end. Judge Jeffrey Saltz denied Inovio’s petition for a preliminary injunction, concluding that the claims are “too speculative.”

“Certainly in assessing the balance of harms, the protection of private property is outweighed by the savings of hundreds of thousands of lives,” the judge wrote. “But in view of Inovio’s inability to show that such a saving of human lives will occur only if a preliminary injunction is issued, VGXI’s property interests cannot be ignored.”

The ruling does not stop Inovio from going to other manufacturers that would use their own proprietary technology, an Inovio spokesperson said.

Meanwhile, the U.S. Food and Drug Administration on Tuesday issued an update on what kinds of data it would require to shortcut the approval of a COVID-19 vaccine.

The agency said “consideration may be given” to using the accelerated approval pathway. Unlike the standard approval process, which requires showing that a vaccine is effective at preventing or reducing infection in clinical trials, the accelerated pathway uses indicators of effectiveness, such as lab measurements of immune cell activation.

The FDA also said it would consider granting “emergency use authorization” on a case-by-case basis, after reviewing clinical data on the vaccine’s safety and effectiveness. Emergency authorization is permitted during a public-health emergency, but it sets a relatively low scientific bar. After the FDA granted emergency authorization to a slew of blood antibody tests, which look for signs of immunity, some of the tests were so unreliable that the agency ordered several off the market.