Minimizing Adjuvant
Vaxart is developing oral vaccines for seasonal and pandemic influenzas based upon a nonreplicating adenovirus 5 vector that expresses both a target antigen such as HA and a piece of double-stranded RNA that acts as an adjuvant via the toll-like receptor 3. According to Mark Backer, Ph.D., CEO, “Presenting the adjuvant and antigen together to the immune system at the cellular level minimizes the amount of adjuvant needed to get a strong immune response to the target antigen. Unlike most vector approaches, performance is unaffected by previous exposure.”
In preclinical trials, the avian flu vaccine showed a strong immunologic response, even against mismatched strains, suggesting it may remain effective as viruses mutate. Animals were protected against lethal challenge by the H5N1 avian flu virus.
To combat the current H1N1 flu strain, a synthesized HA gene with the matching sequence is being used to produce a vaccine without growing the flu virus itself, letting Vaxart produce a vaccine about two months faster than companies that must grow the virus, according to Dr. Backer, who notes that the production rate is expected to be 20 times higher than flu grown in cell culture.
Because the vaccine is oral, it could be delivered by the postal service and administered by patients themselves. As the work has not yet entered clinical trials, Dr. Backer says it may be most beneficial in the event of subsequent waves of the H1N1 flu.
Pulmatrix has developed a “one drug, many bugs” concept that doubles as a preventive and treatment. “It’s not a vaccine replacement. It’s complementary,” emphasizes Bob Connelly, CEO. He says it’s designed for high-risk situations, populations susceptible to respiratory infections, and for those who already have a respiratory infection from any airborne pathogen, including viral and bacterial sources. “It’s pathogen-agnostic,” he says.
The lead drug candidate, PUR003, is an inhaled cationic airway lining modulator composed of positively charged molecules that are simple and safe. “The formulation triggers both physical and biological effects in the airway,” Connelly says.
Phase II trials for influenza are scheduled for this year, with the first beginning in July.