BLUE BELL, Pa., Sept. 6, 2012 /PRNewswire/ -- Inovio Pharmaceuticals, Inc. (NYSE MKT: INO) announced today that the interim analysis of its SynCon® universal H1N1 influenza vaccine showed that it generated protective HAI titers against some of the most prevalent strains of H1N1 influenza from the past 100 years in a phase I clinical trial. Because the SynCon® approach incorporates sequence information from multiple divergent strains, the vaccine is not matched to any of the historical flu strains. The achievement of protective titers against multiple unmatched strains represents a major step towards Inovio's ultimate goal to develop a universal influenza vaccine to protect against known and newly emerging strains of influenza.
"With respect to influenza, our ultimate objective is to develop a universal vaccine capable of providing years of true preemptive protection across subtypes and strains," said Dr. J. Joseph Kim, Inovio's President and CEO. "This is a challenging goal but this proof-of-principle H1N1 data demonstrates the potential of our SynCon® approach to generate cross-protective HAI titers against multiple unmatched influenza strains. These results are an important addition to our previously reported H5N1 phase I data and a validating achievement on our ongoing effort to develop a safe vaccine that provides immunity against the ever-changing influenza virus."
The current open label phase I study evaluated two synthetic H1N1 hemagglutinin (HA) plasmids designed to broadly protect against unmatched influenza strains within different branches of the H1N1 subtype. These plasmids were delivered in healthy adults with Inovio's CELLECTRA® intradermal electroporation device up to three times. The delivered vaccine was well tolerated; reported adverse events and injection site reactions were mild to moderate and required no treatment.
Researchers exposed blood samples from the vaccinated subjects to each of the nine key H1N1 viruses in circulation over the last 100 years: eight were H1N1 strains used to formulate the seasonal vaccines of the last 25 years; one was the H1N1 strain that caused the 1918 Spanish flu, which killed over 40 million people. These unmatched influenza strains were used to assess the generation of hemagglutination inhibition (HAI) titers meeting or exceeding 1:40. An HAI titer of 1:20 is generally regarded as a positive vaccine response, while 1:40 is the level recognized as a protective immune response against influenza in humans. Demonstrating Inovio's synthetic vaccine's broad cross-reactive coverage, a significant percentage of subjects immunized with Inovio's SynCon® vaccine had an HAI titer of 1:40 or higher against each of the nine H1N1 strains tested, ranging from a 30% response rate to the A/ Brisbane/59/07 strain to a 100% response rate to the A/ Beijing/262/95 strain. The benchmark for the current licensed seasonal flu vaccines, which are based on matching the vaccine HA sequence to that of the circulating strain, is to have greater than 65% of the vaccines generate an HAI titer of 1:40 or higher against the matched vaccine strain.By design, Inovio's SynCon® universal flu vaccine is not matched to any single virus and was not matched to any of the strains tested in this study. The vaccine recipients generated protective HAI responses against the H1N1 A/ South Carolina/1/18 strain from the 1918 Spanish flu as well as all the H1N1 strains which were part of the annual seasonal trivalent inactivated flu vaccines (TIV) since 1986, including: A/ Taiwan/1/86, A/ Texas/36/91, A/Bayern/07/95, A/ Beijing/262/95, A/ New Caledonia/20/99, A/ Solomon Islands/03/06, A/ Brisbane/59/07, A/ California/07/09. The HAI titers in the positive responders ranged from 1:40 to greater than 1:1280. Compared to the seasonal TIV (trivalent influenza vaccine)-immunized control group, which is matched to the current H1N1 seasonal flu strain (A/ California/07/09), those immunized with Inovio's vaccine generated a higher or similar percentage of positive HAI titer responders against all of the strains except for A/ California/07/09. As anticipated, the TIV recipients generated the best HAI titers against the matched strain, but did not generate vaccine-induced response rates against the unmatched strains.