Inovio Pharmaceuticals' DNA Vaccine for Foot-and-Mouth Disease Generates Protective Neutralizing Antibodies in Second Large-Animal Study
Robust immune responses achieved in large-animal studies demonstrate potential utility of a vaccine against this fast-spreading livestock disease
BLUE BELL, Pa., June 30, 2011 /PRNewswire/ -- Inovio Pharmaceuticals, Inc. (NYSE Amex: INO), a leader in the development of therapeutic and preventive vaccines against cancers and infectious diseases, announced today that it has achieved compelling immune responses in a study of its multi-subtype DNA vaccine for foot-and-mouth (FMD) disease administered by Inovio's proprietary vaccine delivery technology in sheep, the second large animal in which this vaccine was evaluated. Strong protective neutralizing antibodies were also observed in pigs vaccinated with the same Inovio FMD vaccine. These results were presented by Dr. Niranjan Y. Sardesai, Inovio Sr. VP of Research and Development, at the Biochemical and Molecular Engineering XVII Conference in Seattle in a talk titled "Engineering Effective Consensus DNA Vaccines." Today's FMD vaccines based on killed/inactivated viruses can actually cause FMD infection, so are only used regionally after an outbreak rather than for broad preemptive vaccination. Inovio's synthetic DNA vaccine cannot cause the disease, providing a safe approach to potentially protect against FMD and reduce its serious impact on global food supply and commerce.
The FMD virus is one of the most infectious agents causing significant disease in farm animals including cattle, swine, sheep and goats. Once an area is exposed to FMD, livestock & dairy exports are ceased and herds are culled. For example, in a major FMD outbreak in the UK in 2001, more than 4 million animals were slaughtered, resulting in more than $10 billion (USD) in economic losses. In a current FMD epidemic in South Korea, more than 3.3 million animals, mostly swine, have been culled in an attempt to keep the disease from spreading.
Because FMD can spread rapidly and beyond regional boundaries there is a need to develop vaccines that can simultaneously target different regional serotypes (subtypes) of FMD in a single vaccine. Inovio's SynCon™ technology enables rapid development of vaccines that can cover multiple subtypes simultaneously with a single formulation. Inovio and its academic collaborators have generated and successfully tested SynCon™ DNA vaccine constructs targeting four of the seven main FMD virus subtypes.
FMD is highly infectious. Furthermore, due to the fear of inadvertent spread to farm animals, research with the live virus to test vaccine efficacy is heavily restricted to only a few government laboratories in the US. The investigators therefore developed a new proprietary neutralization assay (using a mock virus unrelated to FMD to assess the ability of the vaccine-induced antibodies to neutralize virus infection). Inovio previously reported the induction of strong cellular and antibody responses in vaccinated pigs after a single vaccination. In a follow-on investigation of the immune responses with the novel neutralization assay against the Asia strain, the vaccinated animals developed neutralizing antibody (NAb) titers averaging 90 after a single vaccination and increasing in magnitude to 191 after two vaccinations. For comparison, commercially available attenuated/killed FMD virus vaccines are able to protect swine with an NAb titer of 32-40. These results are the first report of a DNA vaccine producing high titers of neutralizing antibodies against FMD.
In the second large-animal study, sheep were vaccinated three times at 0, 5, and 10 weeks with a combination vaccine targeting either four subtypes (O, A, C, Asia), three subtypes (O, A, Asia), or a single subtype (Asia). The study investigators observed in the vaccinated animals high levels of seroconversion (production of antibodies specific to a particular antigen) and antibody titers (the actual level of antibody production; in this case, ranging from 1000 – 100,000) to all the vaccine subtypes after only one or two vaccinations. Importantly, the multi-subtype DNA vaccines targeting three or four subtypes simultaneously were able to induce equally strong levels of antibody titers compared to the single-subtype vaccines. Strong T-cell responses (cumulatively > 1,500 SFU/million PBMC), which would potentially play a role in treating the disease, were also noted against the four different subtype antigens. Speaking at the meeting, Dr. Sardesai noted, "Encouraged by these results with four subtypes, we are now expanding the coverage of our vaccine to include the three additional key circulating subtypes – SAT 1, 2, 3 – and will initiate further large animal studies to assess breadth of protection."
Dr. J. Joseph Kim, Inovio's president and CEO, said: "We are pleased to demonstrate these robust DNA vaccine immune responses in a second globally-important farm animal impacted by foot-and-mouth disease. FMD pandemics are a worldwide threat to food supply and society, and the limitations of today's FMD vaccines means they are not able to facilitate adequate protection. Inovio's FMD vaccine program could provide a global solution to this menacing threat to our world's food supply. We look forward to further developing this important vaccine."
About Foot-and-Mouth Disease
Foot-and-mouth disease (FMD) affects cloven-hoofed animals such as cattle, pigs, sheep, goats and water buffalo, and is capable of rapidly infecting large numbers of animals. Seven main types of FMD virus are believed to exist today. Like other viruses, the FMD virus continually evolves and mutates. To date there has been no cross-protection between strains even within the different subtypes of the FMD virus. Vaccine viruses which are not completely killed have resulted in FMD outbreaks, hence vaccines used today are administered to the herd only once an outbreak is detected in an area in order to limit the rapid spread of infection, thus limiting the potential utility of such vaccines.
While death rates are generally low, the highly infectious nature of the virus has a profound negative economic impact, such as in the dairy industry where cattle may experience reduced milk production, poor growth and permanent hoof damage. An FMD outbreak typically leads to economic sanctions, including the loss of export markets, and can negatively impact tourism as restrictions are placed on the movement of people and animals. This was the case in the 2001 outbreak in the UK.
About Inovio Pharmaceuticals, Inc.
Inovio is developing a new generation of vaccines, called DNA vaccines, to treat and prevent cancers and infectious diseases. Its SynCon™ vaccines are designed to provide broad cross-strain protection against known as well as newly emergent strains of pathogens such as influenza. These vaccines, in combination with Inovio's proprietary electroporation delivery devices, have been shown to be safe and generate significant immune responses. Inovio clinical programs include three Phase II studies for vaccines treating cervical dysplasia/cancer, hepatitis C virus, and leukemia. Other clinical programs target influenza (preventive) and HIV (preventive and therapeutic). Inovio partners and collaborators include the University of Pennsylvania, Merck, ChronTech, National Cancer Institute, U.S. Military HIV Research Program, NIH, HIV Vaccines Trial Network, University of Southampton, and PATH Malaria Vaccine Initiative. More information is available at www.inovio.com.
This press release contains certain forward-looking statements relating to our business, including our plans to develop electroporation-based drug and gene delivery technologies and DNA vaccines and our capital resources. Actual events or results may differ from the expectations set forth herein as a result of a number of factors, including uncertainties inherent in pre-clinical studies, clinical trials and product development programs (including, but not limited to, the fact that pre-clinical and clinical results referenced in this release may not be indicative of results achievable in other trials or for other indications, that the studies or trials may not be successful or achieve the results desired, that results from one study may not necessarily be reflected or supported by the results of other similar studies and that results from an animal study may not be indicative of results achievable in human studies), the availability of funding to support continuing research and studies in an effort to prove safety and efficacy of electroporation technology as a delivery mechanism or develop viable DNA vaccines, the adequacy of our capital resources, the availability or potential availability of alternative therapies or treatments for the conditions targeted by the company or its collaborators, including alternatives that may be more efficacious or cost-effective than any therapy or treatment that the company and its collaborators hope to develop, evaluation of potential opportunities, issues involving product liability, issues involving patents and whether they or licenses to them will provide the company with meaningful protection from others using the covered technologies, whether such proprietary rights are enforceable or defensible or infringe or allegedly infringe on rights of others or can withstand claims of invalidity and whether the company can finance or devote other significant resources that may be necessary to prosecute, protect or defend them, the level of corporate expenditures, assessments of the company's technology by potential corporate or other partners or collaborators, capital market conditions, our ability to successfully integrate Inovio and VGX Pharmaceuticals, the impact of government healthcare proposals and other factors set forth in our Annual Report on Form 10-K for the year ended December 31, 2010, our Form 10-Q for the three months ended March 31, 2011, and other regulatory filings from time to time. There can be no assurance that any product in Inovio's pipeline will be successfully developed or manufactured, that final results of clinical studies will be supportive of regulatory approvals required to market licensed products, or that any of the forward-looking information provided herein will be proven accurate.
SOURCE Inovio Pharmaceuticals, Inc.
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