VIRxSYS announces results from prophylactic HIV vaccine study at 2010 CROI conference

“We are extremely encouraged by the results of this study. The combination of strong immune responses, viral control, and CD4 preservation is tremendous. In addition, contrary to most viral vectors currently in development, our lentiviral vector elicits nominal anti-vector responses and therefore can be successfully re-administered,” said Dr. Franck Lemiale, Ph.D., Director of Immunology for VIRxSYS. “It will be very interesting to see how it performs as a therapeutic vaccine in humans.”

“Obviously, the HIV vaccine field has been hit with a number of disappointing trial results over the past several years,” said Dr. Joep Lange, Head of the Amsterdam Institute for Global Health and Development, Professor of Medicine at the Academic Medical Center, University of Amsterdam, President Emeritus of the International AIDS Society, and member of the VIRxSYS medical advisory board for HIV. “The results from this trial are very impressive and I believe could provide real excitement in the world of HIV vaccines.”

VIRxSYS’ vaccine candidate differs from other HIV vaccine candidates in that it employs an engineered HIV-based lentiviral vector to deliver the vaccinating antigens. The study results demonstrate the VIRxSYS vaccine candidate achieves remarkably high levels of T-cell responses, resulting in a 95% reduction of viral load in Rhesus monkeys which received lentiviral vaccination, as compared to non-vaccinated control animals in this study. The investigators also observed a strong and durable immune response without the requirement of a DNA prime and a major preservation of CD4+ T cell compartment as measured by the percentage of CD4+ T cells to total lymphocytes. The lentiviral-based vaccine also elicited high levels of CD107a expression in T cells, which have recently been described as having an important role in the control of SIV/HIV. Importantly, no adverse reactions have been observed in any of the vaccinated animals following multiple infusions of the lentiviral vaccine.

The Company described its intriguing data in Rhesus monkeys, which were divided into two groups receiving either the lentiviral vector vaccine or a mock vaccination as a control. Both groups were infected with a highly pathogenic SIV six months after the last immunization.

“We could not have wished to achieve better results with our lentiviral-based HIV vaccines,” said Gary McGarrity, PhD, Executive Vice President of Scientific and Clinical Affairs for VIRxSYS. “We believe that this lentiviral vector is an excellent HIV therapeutic vaccine candidate to move to human clinical trials. The potential impact of a series of simple injections to treat patients who are currently taking complex and often toxic multi-drug regimens, particularly in the developing world, is enormous. VRX1023 is designed to work against all clades of HIV.”

The VIRxSYS results were presented at CROI on Thursday, February 18, 2010 in San Francisco. In addition, Phase II results for VRX496™, the Company’s investigational RNA therapy for the treatment of HIV/AIDS, also were presented by the University of Pennsylvania School of Medicine on Thursday, February 18, 2010 in San Francisco (poster number 388).