Inovio Pharmaceuticals, Inc., focused on the discovery, development, and delivery of a new generation of vaccines, reported that its synthetic vaccines for influenza Type A H3N2 and Type B achieved protective antibody responses in immunized animals against multiple unmatched strains.
Inovio previously reported that its H5N1 synthetic vaccine achieved hemagglutination inhibition (HI) titers against six unmatched strains of this influenza subtype in a phase I human study. The new flu data was highlighted by Dr Mark Bagarazzi, Inovio's chief medical officer, in a presentation and panel session at Phacilitate Vaccine Forum Washington 2012.
The H3N2, H1N1, and Type B influenza strains represented in each year's seasonal influenza vaccine are updated annually, but only protect against a single strain within each of these subtypes. When the selected strain(s) mutates, the annual vaccine may not provide protection, as witnessed with the 2009 swine flu H1N1 pandemic. There is consequently a global need for a universal vaccine able to provide longer term protection against all existing and potential new strains within the influenza subtypes of concern to humans.
"These new data for H3N2 and Type B in animal models further validate our strategy to develop a universal vaccine to prevent known and unknown influenza strains, as well as our entire SynCon platform. We have in animals provided protection against all of the circulating influenza strains of the last 10 years," said Dr J Joseph Kim, Inovio's president and CEO. "We expect additional H5N1 human data by the end of the first quarter and look forward to human data from our combined H5N1 + H1N1 vaccine in the second quarter of 2012. We expect that data from these studies, coupled with this positive data for H3N2 and Type B, will enable us to launch a clinical study of a comprehensive universal influenza vaccine in 2013."
In the study of Inovio's SynCon H3N2 vaccine, investigators immunized small animals (mice and guinea pigs) with a synthetic vaccine designed to produce the influenza hemagglutinin (HA) antigen in the animals. Inovio investigators have to date tested blood samples from the animals for immune responses against unmatched strains from several clades of H3N2. (Like the branches of a tree, there are dozens of distinct strains within each of these clades). The animals immunized with the SynCon H3N2 vaccine developed HI titers exceeding the 1:40 level commonly associated with protective immunity against several clades of H3N2 tested. These included strains circulating in the 2000-01, 2006-07, and 2008-09 influenza seasons which had necessitated a change in the composition of the seasonal flu vaccine for those years. Additional animal testing of the remaining few H3N2 clades will continue in 2012 and will include a new strain, H3N2v (A/Indiana/10/2011 X203), which was selected this month by the CDC as a pandemic vaccine target.
Similarly, in the study of Inovio's SynCon Type B vaccine, investigators tested blood samples from immunized mice for immune responses against multiple, unmatched strains of Type B influenza. All the animals immunized with the SynCon Type B vaccine developed HI titers exceeding the 1:40 level against all of the strains of Type B tested, including those circulating and consequently a part of the vaccine formulation in 2001-02, 2008-09, and 2011-12. Type B influenza mutates more slowly than Type A, but enough to preclude lasting immunity. Type B influenza can lead to life-threatening complications, including pneumonia, in young children, persons over 50, those with chronic diseases (e.g. diabetes) or suppressed immune systems, and others at risk for complications.
Inovio's novel SynCon technology enables the Company to design synthetic vaccines with the potential to protect against unmatched sub-types and strains of pathogens, including newly emergent, unknown strains of a virus that will periodically emerge through mutation, as in the case of influenza. Inovio has created SynCon vaccine "constructs" based on influenza HA, NA, and NP proteins from strains H1N1, H2N2, H3N2, and H5N1, which are the Type A seasonal and pandemic-potential influenza subtypes currently of greatest concern, as well as for the less common Type B influenza. By designing synthetic vaccines that unlike conventional vaccines do not need to match a virus in order to provide protection, Inovio is aiming to shift the paradigm for protection against infectious diseases such as influenza by providing true, long-lasting prevention against known and unknown strains of pathogen.