ATLANTA, GA -- (Marketwired) -- 10/09/13 --
GeoVax Labs, Inc.(OTCQB: GOVX), a biotechnology company developing vaccines to prevent and treat HIV/AIDS, today presented additional results from HVTN 205, a multicenter, randomized Phase 2a trial evaluating the safety and immunogenicity of the Company's first generation preventive HIV vaccine, at the 2013 AIDS Vaccine Meeting in Barcelona, Spain. At 6 months post-vaccination, patient antibody levels had declined less than 3-fold, indicating significant durability of the antibody response.
HVTN 205 was designed to evaluate the safety and immunogenicity of a prime-boost vaccine regimen of GeoVax's DNA vaccine and MVA (modified vaccinia Ankara) vaccine in healthy, HIV-uninfected adults. The trial extended the safety and immunogenicity results obtained in the Company's earlier Phase 1 trials (HVTN 065 and HVTN 045). In HVTN 205, 299 participants were randomly assigned to three study arms: 149 participants received two injections of GeoVax's DNA vaccine followed by two injections of the company's MVA vaccine (DDMM arm), 75 participants received three MVA injections followed by one placebo injection (MMM arm), and 75 participants received four injections of placebo. After the final vaccination, antibody responses against the HIV Envelope protein (Env), the target for protective antibody, were detected in 93.2% of the DDMM arm (the vaccination regimen selected for further clinical study). At six months after final vaccination (the latest time point tested), gp140 IgG antibody response titers in the DDMM arm had declined by less than 3-fold, with response rates only declining from 100% to 84%, indicating significant durability of the antibody response. Additionally, HVTN 205 also showed that the antibody responses after vaccination had high affinity binding, a characteristic which has been associated with prevention of HIV infection in preclinical models.
"We are very pleased with the durability of our antibody responses," said Dr. Harriet Robinson, Chief Scientific Officer at GeoVax. "We are also encouraged that our vaccine is eliciting tightly binding Ab in humans. The key to a successful preventive vaccine is the antibody response, which needs to be both sustained and capable of high affinity binding."
HVTN 205 was conducted by the HIV Vaccine Trials Network (HVTN), with financial support from the National Institute of Allergy and Infectious Disease (NIAID) of the National Institutes of Health (NIH). The HVTN is currently conducting a Phase 1 trial (HVTN 094) of GeoVax's second-generation DNA/MVA vaccine, which co-expresses an adjuvant (GM-CSF) in the DNA vaccine. The dosing regimen during this trial follows a vaccination schedule similar to the DDMM arm of HVTN 205. In the preclinical model, co-expressed GM-CSF has enhanced antibody responses and increased prevention of infection by serial rectal challenges. Pending the success of HVTN 094, GeoVax expects to begin a Phase 2a trial of the GM-CSF-adjuvanted vaccine in 2014.