VGX Pharmaceuticals Presents Non-Human Primate Study Data At AIDS Vaccine 2008 Conference

Main Category: HIV / AIDS
Also Included In: Immune System / Vaccines;  Clinical Trials / Drug Trials
Article Date: 16 Oct 2008 - 7:00 PDT

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VGX Pharmaceuticals (VGXP), a developer of DNA vaccines against cancer and infectious diseases, presented today non-human primate study data from both its PENNVAX™ HIV Vaccine Program and its patented CELLECTRA® DNA Delivery technology in two presentations at the AIDS Vaccine 2008 Conference currently taking place in Cape Town, South Africa.

These studies were conducted in collaboration with researchers at the University of Pennsylvania. The studies showed that significant T cell mediated immune responses were generated in non-human primates in response to primate analogues of VGXP's human DNA vaccine candidates (consensus Env, Gag, and Pol), when delivered with the CELLECTRA® device. Most notably, monkeys immunized with VGXP vaccines displayed HIV-specific T cell responses as much as 10 to 20 times greater than those reported in the literature using other vaccine modalities, including DNA vaccines without electroporation. The immunogenicity of the DNA vaccines can be further enhanced upon the inclusion of cytokine adjuvants together with electroporation. Induction of high levels of T cell immune responses, especially the CD8+ Killer T cell responses, has long been thought to be important for developing a successful vaccine for HIV.

Furthermore, the animals vaccinated by the DNA + EP (electroporation) route were able to control viral load in a difficult primate mucosal challenge against the SIVmac251 viral challenge. The vaccinated animals had as much as 10 to 100 times lower virus levels in their bloodstream than the control animals after the challenge. These results were presented today in a talk entitled "Induction of Potent T Cell Immunity in Macaques by EP DNA + Molecular Adjuvants" delivered by Professor David Weiner of the University of Pennsylvania School of Medicine.

A second presentation compared VGXP's intramuscular (IM) DNA delivery device with its intradermal/subcutaneous (ID/SQ) delivery device in eliciting robust cellular and humoral immune responses in non-human primate models for HIV and H5N1 influenza. In particular, CELLECTRA® ID/SQ EP delivery of avian influenza vaccines elicited strong and protective neutralizing antibodies against H5N1 viruses. VGXP has validated the CELLECTRA® IMEP device for use in human clinical trials and has opened an IND for studying its therapeutic vaccine candidate for cervical cancer (VGX-3100) delivered by the IMEP device. These data suggest that the CELLECTRA® ID/SQ EP device could also be a viable approach for the delivery of vaccines.

"We are excited by the pre-clinical data generated in our HIV vaccine program and the opportunity to present at the prestigious AIDS Vaccine 2008 Conference, which brings together scientists and the global community to share findings in this important area. We have developed two complementary delivery platforms and we look forward to translating the findings in a clinical setting," stated Dr. J. Joseph Kim, President and CEO of VGX Pharmaceuticals.

DNA vaccines, comprising plasmid DNA encoding proteins from pathogens, allergens, and tumors offer potential benefits in protective efficacy, cross-strain applicability, development speed and manufacturing cost compared with conventional vaccines. DNA vaccines were believed to be particularly useful in inducing killer T cell responses which are an important ingredient in fighting infections. The results of this study show that a combination of VGXP technologies can achieve this important, long-sought-after result in the difficult primate model system.

VGXP was recently awarded a $23.5 million contract, by the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health, to develop a preventive HIV DNA vaccine candidate in conjunction with its constant current electroporation technology for ID delivery of DNA vaccines.

http://www.vgxp.com.