Sanofi Pasteur, the vaccines division of Sanofi, has released plans on developing broadly cross-reactive antigens against seasonal and pandemic influenza.
Harry Kleanthous, Ph.D., associate vice president for research, discussed the paradigm shifting potential of broader-spectrum influenza vaccine approaches that stimulate protection against many influenza strains, unlike the current licensed vaccines that are designed to protect against three to four strains that are determined before the influenza vaccine production process begins each year.
“We are actively exploring the development of a more-broadly protective influenza vaccine that will be designed to prevent the seasonal mismatches that can occur and that are not addressed using the current technology,” said Kleanthous. “They are complementary but can be considered ‘tailored’ antigens in that they are designed to re-focus the immune response to key protective epitopes on the hemagglutinin, which is the active component of our currently licensed influenza vaccines. These antigens are still a key player in any flu vaccine, since antibodies directed against them are responsible for preventing the Flu virus from binding to and infecting the cell. Creating new antigens is a central theme in our strategy.”
Sanofi Pasteur has an existing R&D collaboration agreement with the University of Georgia on a method that, according to Kleanthous, could yield a novel, synthetic vaccine based on the hemagglutinin protein, designed to protect against seasonal influenza strains spanning several years, including drifted strains not yet in existence. Traditional influenza vaccine manufacturers are directed by, and provided with candidate vaccine viruses from public-health authorities determined through active surveillance of influenza viruses circulating each year.
Sanofi Pasteur’s experimental vaccine is a novel synthetic vaccine generated from key genetic sequences of many flu viruses, is termed “computationally optimized broadly reactive antigen” (COBRA) and is designed to protect against many strains over several years, due to the common sequences many flu viruses share. The key advantage is broader coverage against several seasonal flu strains, which is important when there is a mismatch to the vaccine strain. An additional advantage of the approach is not relying upon annual strain selection, allowing year-round manufacturing.
According to Sanofi Pasteur Senior Vice President for R&D John Shiver, Ph.D., a universal flu vaccine will need to be compared against the standard-of-care (seasonal vaccines), showing safety, comparable immunogenicity, and efficacy in human clinical trials over several years against a range of influenza virus strains.