Inovio Moving Quickly on Zika Vaccine Trials in Puerto Rico
SAN JUAN— When news broke in late August that Inovio Pharmaceuticals, a Pennsylvania-based biotech company, would launch a trial of a Zika virus vaccine involving 160 patients in Puerto Rico, many observers stood up and took notice. However, the sheer importance of this clinical trial may have been lost on most people.
As it turns out, the Puerto Rico clinical trial marks only the third effort related to Zika prevention worldwide, and the largest in terms of the number of volunteers, Inovio CEO Joseph Kim told Caribbean Business in an exclusive interview. “Regarding the Puerto Rico clinical trial, it should prove particularly important in the search for an effective vaccine because of the prevalent exposure to the virus on the island,” he said.
Inovio is also carrying out a much smaller trial, comprising some 40 volunteers across the U.S. mainland and Canada, specifically Miami, Philadelphia and Quebec City. A third trial, carried out by the National Institute of Allergy and Infectious Diseases’ Vaccine Research Center, is taking place at three study sites in the U.S., including the National Institutes of Health Clinical Center in Bethesda, Maryland, with 80 volunteers signing up.
The vaccine is being developed with South Korea-based GeneOne Life Science Inc. and academics from the United States and Canada, who are also working on Inovio’s Ebola and MERS (Middle East Respiratory Syndrome) vaccines.
When it comes to the ongoing outbreak of the Zika virus in the Western hemisphere, Puerto Rico has become a particular focal point. Concerns about the virus, especially its link to brain-abnormality cases in newborns, has captured headlines and placed a further strain on the wellbeing of residents, as well as the tourism sector, in the economically embattled U.S. territory.
The latest reports from the local Health Department only seem to underline the severity of the problem on the island, with a total of 24,127 cases confirmed since the agency began monitoring the virus some eight months ago. Of these, 127 confirmed cases consist of pregnant women, while instances of Guillain-Barré syndrome, which has been also linked with the Zika virus, number around 50. Moreover, the Centers for Disease Control (CDC) expects more than 25% of Puerto Ricans to contract Zika by year’s end.
Several steps have been carried out in Puerto Rico and elsewhere to halt the contagion -including stopping the spread of the Aedes aegypti mosquito that serves as the virus’s main vector- but perhaps the most important efforts concern the ongoing development of a Zika vaccine capable of providing immunity to a large segment of the population.
Recruitment of volunteers for the Inovio clinical trial has been ongoing at the University of Puerto Rico Medical School, Kim explained, with volunteers receiving a small stipend to participate.
Out of 160 volunteers, 80 would receive the DNA vaccine, which according to the company, does not carry the risks associated with conventional vaccines, with the remaining 80 receiving a placebo.
“We don’t use any viruses, live or killed,” Kim explained. “Because we use snippets of DNA instead of the whole virus, i’ts designed to be much safer.” Volunteers will receive the vaccine or placebo through a proprietary intradermal DNA delivery device called a Cellectra-3P.
The trials -which are catalogued as Phase 1, or the first stage of testing in human subjects- will mainly look for immune responses, Kim noted. “Because Zika is going to be more prevalent in areas where people have been exposed to dengue, we’re specifically looking for people who’ve had previous exposure to dengue, and in Puerto Rico that should be most of the population,” he added.
Such trials are scheduled to last for about a year, Kim said, adding that the large volunteer sample on the island is due to the fact that there’s an actual infection going on the island. “We want to see the effectiveness of the vaccine as rapidly as possible in a reasonable sample size, so putting all of those design statistics in consideration, that how we came up with 160 [volunteers].”
When asked if the trial was looking into pregnant women, one of the populations who is most at risk from Zika-related complications, Kim answered that, on the contrary, “we’re excluding pregnant women just because this is an exploratory trial, we need healthy volunteers, adults 18 to 55 [years old].”
Among the medical and scientific community, concerns have arisen regarding a phenomenon called antibody-dependent enhancement, or ADE, which can mainly occur in patients previously infected with dengue. Through ADE, a second exposure with dengue can “trick” the immune system into actually making the infection worse for the patient. Because Zika, like dengue, is a type of flavivirus, there is worry that a Zika vaccine could provoke a similar response in patients.
“The whole concept of ADE is a scientific concern and certainly medical concern for dengue disease, whether that’s totally translated into Zika or not, that is information that is still being gathered,” Kim noted. “There are many theories about that because they’re in the same type of flaviviruses, there will be a lot more data to be gathered and this study may directly help address those questions as well.”
Kim also dismissed the possibility of complications related to Guillain-Barré syndrome. “I don’t think [it]will be factor in because our vaccine is non-live, non-spreading, it’s just using methods of DNA,” he said. “The potential for Guillain-Barré will be much smaller if at all than what inactivated or live attenuated viral vaccines are trying.”
Apart from the aforementioned trials, the company is also going into a global Phase III pivotal trial for treating cervical disease, and which uses many of the same technologies, Kim noted.
“We’ve shown we can generate the highest level of immune responses’” he said. “Because it’s safer and much easier to design, that’s why we were the first one in the clinic, and Zika just provided an opportunity to have everyone begin at the same starting line, and DNA vaccines have been the first ones to get a positive data from these trials.”