Partial success reported in the Phase 3 trial of HIV/AIDS vaccine

Sep 25 2009

GeoVax Labs, Inc. (OTC Bulletin Board: GOVX) (the "Company"), an Atlanta-based, biopharmaceutical company developing human vaccines for HIV/AIDS (HIV-1, Human Immunodeficiency Virus), was pleased to hear the announcement today of partial success in the recently completed Phase 3 trial in Thailand of a candidate HIV/AIDS vaccine owned by Sanofi-Aventis and Global Solutions for Infectious Diseases. The completed study represents the first HIV/AIDS vaccine trial to show prevention of infection.

Robert McNally, Ph.D., Chief Executive Officer and President stated, "The results are highly encouraging for the clinical studies of our HIV/AIDS vaccine and we congratulate the Thai ministry of Public Health for successful conduct of a groundbreaking trial that included 16,000 volunteers and was supported by multiple agencies including the U.S. Army and the U.S. National Institutes of Health (NIH)."

"The partial success of this trial is very important to the GeoVax vaccine, because the vaccine tested in Thailand, like the GeoVax vaccine, was designed to elicit both T cells and antibody," said Dr. Harriet Robinson, Senior Vice President of Research & Development. "The two vaccines that have failed in previous efficacy trials elicited only antibody or only T cells. This was the first efficacy test of a vaccine that elicited both antibody and T cells and is very encouraging for the GeoVax vaccine, because our vaccine generates higher frequencies of T cells and better quality antibody. Given what we know about the elicited responses observed in this study, and the similarities and differences between our vaccine and the Sanofi-Aventis vaccine, the GeoVax vaccine should be poised for a higher level of protective success than the 30% success rate achieved in Thailand," noted Dr. Robinson.

"Within the two main areas of focus for our HIV/AIDS vaccine - preventative and therapeutic - we continue to make progress," stated Dr. McNally. "The preventative version of the vaccine has advanced to a Phase 2a human clinical trial, which was initiated in February 2009 by the HIV Vaccine Trials Network (HVTN) and continues to have steadily increasing enrollment. On the therapeutic vaccine, we continue to plan out the details of a Phase 1 human clinical trial and expect to begin this trial, assuming U.S. Food and Drug Administration (FDA) concurrence, in the first quarter of 2010."

The Technology

GeoVax's unique two component vaccine, a recombinant DNA and a recombinant modified vaccinia Ankara (MVA), is designed to stimulate both anti-HIV T cell and anti-HIV antibody immune responses. GeoVax's DNA and MVA vaccines are used in a prime-boost protocol in which priming is done with the DNA and boosting with the MVA. GeoVax is also investigating a potentially simpler regimen in which MVA is used for both priming and boosting. Both the DNA and MVA express the three major proteins of the AIDS virus: Gag, Pol, and Env, and produce non-infectious virus-like-particles. These particles contain proteins that mimic more than half of the components of the AIDS virus, but cannot cause AIDS. This multi-protein approach is designed to elicit a broad multi-target protective T cell response. The Env protein is designed to elicit a protective antibody response against the natural form of the virus envelope glycoprotein as well as protective T cells.

"One of the strong features of our vaccines is their stability during manufacture," said Dr. Robinson. "During development, we and our collaborators at the National Institutes of Health persevered to construct vaccines that showed solid stability under commercial manufacturing conditions. We did not advance a vaccine until we had demonstrated stability. We have available inventory and can readily contract manufacture additional product," added Dr. Robinson.

HIV affects the entire globe and comes in a variety of subtypes. Clade B is the predominant subtype in North America, where there are roughly 60,000 new infections each year. Globally, there are about 2.5 million AIDS infections per year, most primarily involving subtypes AG, B, and C. In 2007, UNAIDS reported 1.3 million people living with AIDS in North America and 33.2 million people living with AIDS worldwide. Whereas the Thai trial was conducted with a vaccine targeted for infections endemic to Thailand; the GeoVax vaccine is targeted for the "clade B" type of HIV-1 prevalent in the Americas, Europe and Australia.