Preclinical data from Vical Inc. gave strength to the theory that a universal vaccine could protect against several flu strains, including those feared to cause a deadly pandemic, and the company's stock was lifted by 30.7 percent.
Shares (NASDAQ:VICL) shot up $1.69 Tuesday to close at $7.19, after the company reported that its lead three-component influenza DNA vaccine candidate provided full protection in mice and ferrets against lethal challenges with a highly virulent H5N1 avian influenza virus.
In essence, the mice and ferrets that received the vaccine lived. The ones that didn't died.
For years, scientists have played a guessing game, trying to decide what each year's flu strain might be so they could create a vaccine to combat it. If they're wrong, people get sick. And if it's a violent strain, such as the H5N1 virus or others, the results can be devastating.
But Vical's preclinical data suggest that a vaccine might one day offer humans cross-protection against several strains.
While conventional vaccines address H5 or the "jacket" and the "trousers" of the flu pathogen, Vical's vaccine targets nucleoprotein (NP) and matrix protein (M2), or the "undershirt" and "jockey shorts," said Vijay Samant, the company's president and CEO.
"The beauty about NP and M2 are, unlike the jacket and the trousers that change from strain to strain, the NP and M2 are pretty conserved," he told BioWorld Today.
The San Diego-based company looked at the influenza strains that circulated from 1990 to 2000 and came up with the common denominator to create its vaccine. It then challenged vaccinated mice with the Vietnam avian influenza strain and were able to show protection in more than 80 percent of animals.
"In principle, what you can do is you can start making a vaccine well in advance of knowing what strain is circulating," Samant said. "We could start vaccinating humans today, protect 80 percent of them and develop H5 once we know exactly what it is."
The company's vaccine, which targets the variable H5 avian influenza virus surface protein and the two conserved influenza virus proteins, is formulated using Vical's Vaxfectin adjuvant, which showed statistically superior protection in mice, compared with other formulations.
Like all DNA vaccines, the Vaxfectin formulation does not rely on chicken eggs or complex cell culture manufacturing methods. DNA vaccines are manufactured through bacterial fermentation methods and can be produced in high quantities in a short period of time and easily stockpiled, Samant said.
Vical's lead vaccine not only kept alive all mice and ferrets that received it shortly before being challenged with the H5N1 avian flu virus, but also appeared to prevent weight loss, suggesting it has a benefit in preventing serious flu-related sickness. All animals that received the blank DNA control died. Each group included 16 mice or six ferrets.
Vical took its research a step further by testing a simplified two-component DNA vaccine, which targeted only the two conserved influenza virus proteins.
Although the vaccine did not target an avian influenza virus surface protein, it still provided protection against avian flu to 14 of the 16 mice in each of two vaccine groups. They survived with only moderate weight loss.
The study represents the first time a company has been able to show that a vaccine targeting conserved influenza virus proteins without matched surface proteins can provide protection against a lethal H5N1 flu strain, as well as two strains of human influenza.
"Every year, the flu vaccine is developed on the choice of strains," Samant said, "and occasionally, the CDC, or the people who pick the strains, make an error and the conventional vaccines are even less effective."
There is even a likelihood that the H5N1 virus could mutate before it becomes transmissible between humans, making the need for a cross-protective vaccine all the more relevant.
The preclinical work was funded through a grant from the National Institute of Allergy and Infectious Diseases. Samant expects the program to move into a 100-patient to 200-patient immunogenicity study "as soon as possible," but said, "We're not going to do this program without government funding." He added that he should know more within three to six months.
Once it has human data, Vical expects to seek a partner. Since it involves a new modality, the vaccine might require extensive clinical work before reaching the regulatory stage, although Samant hopes strong human data will help accelerate the timeline.
"Unlike traditional programs where you have a clear regulatory pathway," he said, "the pandemic pathway is going to be dependent on how fast the regulatory agencies want to move and how imminent the threat is."
In addition to a fast-track pandemic pathway for Vical's vaccine, the company expects to pursue development of the product as a cross-protective vaccine for the regular flu - one that might offer protection for more than one year.
According to the London-based market analysis firm Datamonitor plc, influenza vaccines had global sales of $1.3 billion in 2004 and are expected to rise to $3.7 billion by 2010.
Vical also develops DNA vaccines for other infectious diseases and cancer, and it is advancing cardiovascular therapies. It holds all rights to its internally developed product candidates.
"The beauty of vaccines," Samant said, "is any vaccine that gets Phase II proof of concept usually gets approval."
The influenza vaccine studies in mice and ferrets were conducted by Richard Webby, of St. Jude Children's Research Hospital, who is presenting the data today at the U.S. Public Health Service Professional Conference in Denver.
Vical also reported its first-quarter results on Tuesday, showing revenues of $5.6 million, a net loss of $4.5 million - or 16 cents per share - and $57 million in cash, cash equivalents and marketable securities as of the end of March.
The company expects a net loss for 2006 of between $22 million and $26 million.