The U.S. health regulator has put a hold on Inovio Pharmaceuticals Inc's <INO.O> plans to start final trials of its coronavirus vaccine as the agency seeks more information, including details on a delivery device used to inject genetic material into cells.
The mid-to-late trials, which were awaiting approval from the U.S. Food and Drug Administration, were scheduled to start this month after they were postponed from this summer.
The drug developer said on Monday the latest delay due to the FDA's "partial clinical hold" was not due to any side effects in the early-stage study of the vaccine, which was continuing.
Shares of Inovio fell nearly 25% in morning trading as the gap widened with rival coronavirus vaccine developers Moderna Inc <MRNA.O>, Pfizer <PFE.N> and AstraZeneca Plc <AZN.L> that have already begun late-stage trials.
Inovio said it would respond to FDA's queries in October, after which the U.S. agency would have 30 days to decide whether the trial should proceed. Tentatively, the earliest the trial could start now is November.
"It's not guaranteed that Inovio will have the all-clear from FDA to start the trial once it hears back from the agency in November," Piper Sandler analyst Christopher Raymond said.
Inovio planned to administer the vaccine to study participants through a device called Cellectra, which sends out an electrical pulse to open pores in a cell so DNA molecules can enter.
The vaccine focuses on specific genes on the outer "spike" portion of the coronavirus and was designed using Inovio's DNA medicine platform.
The company, which has no approved drug in the market, has received $71 million in funding from the U.S. Department of Defense to scale up manufacturing of Cellectra.
When it announced the funding this summer, it said it could expand production beyond its manufacturing plant in San Diego through contract manufacturers.
(Reporting by Manas Mishra in Bengaluru; Editing by Shinjini Ganguli)
