Experimental Zika vaccine is approved for clinical trials for first time in US

The Food and Drug Administration on Monday for the first time approved a clinical trial for an experimental vaccine for Zika virus, an early but significant step in the effort to combat a disease that has quickly emerged as a global health threat.

The first people could be injected within a few weeks, said Inovio President and CEO Joseph Kim. Inovio, of Plymouth Meeting, Pa., and GeneOne Life Science, of Seoul, South Korea, will make the vaccine.

“We were the first to construct the vaccine,” Kim told STAT. “And now as of this morning, we were the first to get the OK from the US FDA to start the human studies.”

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Interim results from the trial, which will involve 40 healthy adults, are expected later this year. Testing in mice and monkeys has shown the vaccine triggered what Inovio called a robust antibody response.

Gary Kobinger, whose team at Canada’s National Microbiology Laboratory in Winnipeg did the mouse testing, said the Inovio team decided late last year to try to develop a Zika vaccine in the shortest time it could.

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Kobinger said the approval arrived a mere nine months after the group convened by teleconference and decided to pull out all the stops.

“I think that’s really phenomenal,” said Kobinger, chief of special pathogens at the Winnipeg lab and the scientist who oversaw the optimization of the experimental Ebola treatment ZMapp.

The Inovio Zika product — which goes by the working name GLS-5700 — is a so-called DNA vaccine. In that kind of vaccine, DNA coded to produce the protein that surrounds the Zika virus is injected into the skin.

The site of the injection is zapped with a device that delivers a short electrical pulse that helps the DNA find its way into cells — a process called electroporation.

The cells then start the process of training the immune system to see the Zika virus as a foreign invader that needs to be attacked, generating antibodies to fight it.

FDA approval to begin human testing of another Zika vaccine may be just a few weeks off.

The National Institute of Allergy and Infectious Diseases is also designing its own DNA Zika vaccine. NIAID director Dr. Anthony Fauci said Monday that preliminary paperwork for this vaccine is already before the FDA and results from animal testing look promising.

“Our pre-clinical data with that candidate shows good immunogenicity,” Fauci told STAT in an email. “We had projected that we would start our Phase 1 trial in September; it now looks like we may be able to start in mid-August.”

The move to quickly test a Zika vaccine reflects a sense of urgency surrounding efforts to develop a vaccine. But if this — or any other experimental Zika vaccine — looks promising, there are still several years of testing and development work ahead before patients could head to their doctors’ offices to get a protective shot.

So-called Phase 1 trials don’t reveal if a product works, but they can provide hints. These small trials are designed to determine whether a product is safe to administer to people and to determine the effective dosage.

“This doesn’t mean that there will be a vaccine available in 2017,” Dr. Marie-Paule Kieny, the World Health Organization’s point person for development of drugs and vaccines for new disease threats, told STAT.

The Geneva-based global health agency is in the process of finalizing what it calls a “target product profile” — in essence, telling industry what kind of vaccine is likely to find the shortest path to regulatory approval.

The target population for a Zika vaccine would be pregnant women and women of child-bearing age. That means the safety bar must be high. Vaccines made out of live but weakened Zika viruses would not be a first — or second — choice. An effective DNA vaccine would likely satisfy safety concerns.

Kieny noted that there has been a lot of work on DNA vaccines in the past, for different diseases, but none have made it to market.

The blunt truth: they didn’t work. She noted, though, that the addition of electroporation to the vaccine delivery process seems to have made “a whole lot of difference.”

Earlier this year the WHO estimated 18 companies and academic laboratories were working on a vaccine. Kieny said progress has been made since, but noted some of the big players in vaccine production are still assessing whether they can or should jump in.

A number spent a lot of money trying to develop an Ebola vaccine during the height of the West African outbreak and are looking for some assurances there will be public money to help defray the Zika development costs.

But raising money for a Zika response has bedeviled many of the organizations trying to do so.

Kim said that Inovio believes one dose of its vaccine should be adequate to protect, but the company will also test a two- and three-dose regimen, with shots given one month apart.

Inovio has multiple DNA vaccines in its pipeline, both for infectious diseases and for cancers. But to date, it has not brought a vaccine all the way through to licensure. Its most advanced product, a cancer vaccine, has gone through Phase 2 testing and will begin a Phase 3 trial later this year.

Kim insisted his company has the capacity to bring the Zika vaccine all the way to the market, though it currently does not have production facilities that can make the vaccine at commercial scale.

“We don’t have a large factory just sitting around waiting for the vaccine to be approved. But we can marshal those resources as needed with the given timeline that we expect,” he said.

But whether Inovio or a commercial partner would take the vaccine into full-scale production is not yet clear. The company has license agreements with Roche and MedImmune, a subsidiary of AstraZeneca, for other products, Kim noted.

“We’re going to do what’s best for the development of the product as well as the best for Inovio and our shareholders,” he said, noting the company has received offers of help from governments and the WHO.

“And once we start the trial I think those potential partnerships can coalesce much faster, when there’s a tangible project to rally behind.”