VGX Pharmaceuticals Avian Influenza DNA Vaccine Delivered with Electroporation Provides 100% Protection of Non-Human Primates

Novel DNA Vaccine Protects Against Multiple, Unmatched Avian Influenza Sub-Types and Shows Utility of Intramuscular and Intradermal Electroporation-Based Delivery

BLUE BELL, PA, USA | February 23, 2009 | VGX Pharmaceuticals Inc. (VGX), a leading developer of DNA vaccines and therapies for infectious diseases and cancer, announced today preclinical results indicating that its avian influenza DNA vaccine delivered using intramuscular or intradermal electroporation provided 100% protection of non-human primates against the H5N1 avian influenza virus. The vaccine also provided protection against multiple unmatched avian influenza strains. The data was published in the Journal of Virology in a paper titled, “Electroporation of Synthetic DNA Antigens Offers Protection in Non-Human Primates Challenged with Highly Pathogenic Avian Influenza.” The results support advancing this DNA vaccine candidate into human clinical studies.

The study, undertaken by VGX in collaboration with researchers at the University of Pennsylvania, tested VGX’s avian influenza DNA vaccine candidate, VGX-3400, delivered via electroporation in non-human primates following previous successful challenge studies in mouse and ferret models. This vaccine combines three SynCon™ based consensus vaccine constructs targeting H5-influenza HA, NA, and M2e-NP antigens, but not matched to a specific strain in either of the two main families (clade 1 and clade 2) of avian influenza. The researchers tested intramuscular and intradermal routes of DNA vaccine delivery using the CELLECTRA® electroporation device.

Following two immunizations, 100% of the macaques in both the intramuscular and intradermal groups developed hemagglutination inhibition (HAI) titers greater than 1:40 against a clade I H5N1 virus. Antibody responses amounting to HAI titers greater than 1:40 are classically considered sufficient to provide protection against the influenza virus in several animal models and humans.

Notably, the vaccine also elicited robust HAI titers (greater than 1:40 in most animals) against non-matched clade 2 viruses (sub-types 2.1; 2.2; 2.3.4), suggesting the potential to address strain variations and provide broad cross-clade protection.

While achieving potent humoral (antibody) immune responses, the vaccine also induced significant cellular (T-cell) immune responses to each component antigen. T-cell responses are believed to be important in protecting from the morbidity and potential mortality associated with influenza infection. Having cellular immune responses present to augment incomplete or absent antibody responses could significantly impact the toll of epidemic and pandemic influenza.

Following immunization, the animals were challenged with the A/Vietnam/1203/04 strain. The vaccinated animals showed significant reduction in average viral load and decreased symptoms of disease compared to non-vaccinated controls.

“This study was the first to demonstrate that synthetic DNA vaccines delivered with electroporation can protect non-human primates from a highly pathogenic H5N1 avian influenza virus challenge,” stated Dr. J. Joseph Kim, President and CEO. “We have demonstrated in multiple animal models the ability to achieve broad immune responses and cross-protection against multiple, unmatched avian influenza strains. These positive results support the promising ongoing development of our universal influenza vaccine program.”

About VGX’s Avian Influenza DNA Vaccine

The highly pathogenic avian influenza (HPAI), or "bird flu," virus is an emerging threat that has killed millions of poultry in a growing number of countries. Health experts are concerned that co-existence of human and avian flu viruses (primarily sub-type H5N1) will provide an opportunity for genetic material to be exchanged between the species-specific viruses and possibly create a new virulent influenza strain that is easily transmissible and lethal to humans. The pandemic potential of bird flu highlights the need for novel vaccination techniques that can quickly and effectively respond to emerging viral threats and specifically address the issue of rapidly evolving strain variations.

Using its SynCon™ technology, VGX identifies antigens and genetic sequences that are common across a set of viral sub-types or taxonomic groups. Combining the synthesis of optimized consensus gene constructs to produce the identified antigens with highly efficient delivery facilitated by electroporation, VGX aims to produce DNA-based vaccines that are safe but have powerful preventative and/or therapeutic capabilities against challenging infectious diseases such as avian influenza. Pertinently, VGX’s approach facilitates rapid vaccine design and development and has the potential to enable sufficiently robust and broad immune responses to emerging strain variants.

VGX’s universal influenza DNA vaccine program is focused on developing a vaccine capable of addressing both seasonal and prospective pandemic influenza strains.

About VGX Pharmaceuticals

VGX Pharmaceuticals is a biopharmaceutical company with DNA vaccines and small molecule product candidates for the treatment of infectious diseases, cancer, and inflammatory diseases. The Company has entered into a definitive merger agreement with Inovio Biomedical Corporation (NYSE Alternext: INO). More information about VGX can be found at

SOURCE: VGX Pharmaceuticals Inc.

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