GeoVax Labs to launch phase II trials of HIV vaccine candidate

The Atlanta-based biotechnology firm GeoVax Labs plans to launch Phase II clinical trials of its experimental HIV vaccine this summer, company officials recently announced, the Atlanta Journal-Constitution reports (Hendrick, Atlanta Journal-Constitution, 5/8).

GeoVax while in midstage development of its HIV vaccine candidate enrolled 140 people in four independent national trials. The firm is developing the experimental HIV vaccine in collaboration with Emory University, CDC and NIH. According to Emory officials, a prototype of the vaccine provided long-term protection against development of AIDS in nonhuman primate studies conducted more than three years ago at the Yerkes National Primate Research Center in Atlanta. NIH awarded the firm a $15 million grant in October 2007 to further its research and continue human clinical trials (Kaiser Daily HIV/AIDS Report, 10/1/07).

The vaccine is the only candidate among several under development that is "on the verge" of being moved to Phase II trials by the HIV Vaccine Trials Network, the Journal-Constitution reports.

"The upcoming Phase II trial is being conducted in a larger number of healthy individuals," Bob McNally, president and CEO of GeoVax, said. He added, "Now that the delivery combinations of the vaccine have been worked out, the Phase II trial will expand the participants to 150 vaccinated volunteers and 75 volunteers as a control group who do not receive the vaccine."

The trial participants are not at risk of contracting HIV, and the purpose of the study is to gauge the CD4+ T cell and antibody response to the vaccine, according to McNally. "The significance of the results will be to give a level of comfort" to FDA and GeoVax that when the vaccine is given to at-risk participants, there will be a "high degree of likelihood that the patients will be protected from contracting the disease," McNally said.

"We've had excellent results in our early stage human trials," Harriet Robinson, chief scientific adviser to GeoVax, said. She noted that no vaccine has ever prevented infection but that she hopes the candidate will "prevent the development of disease and transmission." Robinson also said she hopes the vaccine might ultimately be administered to adolescents.

Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition, said the vaccine's advancement to Phase II trials is a significant achievement. GeoVax's Phase I data are "compelling and warran[t] taking (the vaccine) into Phase II," he said. "But there is still much more to be done," Warren said. He added, "You are not looking for efficacy in these trials. That comes later in much larger trials. With GeoVax, they're still in the early phases of product development. The early data look good. If it looks good after Phase II, it will go into Phase III. There are still a number of more hurdles."

Warren noted that several candidates have advanced to Phase II trials, adding that two of three that advanced to Phase III have failed. Don Hildebrand, board chair of GeoVax, said that "only a handful of AIDS vaccines have reached" the same level of evaluation as GeoVax's (Atlanta Journal-Constitution, 5/8).