October 5, 2009 • Posted in Project R&R News
On September 24, 2009, results from an HIV vaccine clinical trial (known as the Thai Phase III HIV vaccine study or RV144) revealed a new experimental vaccine to be 31 percent effective in preventing HIV infection. Over 16,000 men and women participated in the trial, which was conducted in Thailand by the Thai Ministry of Public Health and sponsored by the U.S. Army Surgeon General in collaboration with the Department of Defense and the National Institute for Allergy and Infectious Diseases.
This is welcome news, but according to Dr. Jarrod Bailey, Science Director of Project R&R: Release and Restitution for Chimpanzees in Laboratories, optimism should be guarded. Notably, greater than two-thirds of the human trial participants remained unprotected from HIV infection. Further, the vaccine’s efficacy in other racial groups and against other strains of HIV remain to be seen.
A comprehensive review by Project R&R revealed that components of the RV144 vaccine have been widely tested in other trials in humans and animals, including chimpanzees. According to Bailey, previous failures and the limited efficacy of this vaccine are the result of misleading data from chimpanzee experiments. Further, variants of the “ALVAC” component have been trialled alone and in combination with other vaccine types. Almost all provided protection from HIV infection in chimpanzees, but all failed in humans. The “AIDSVAX” component failed to protect several thousand clinical trial volunteers, despite many similar vaccines protecting chimpanzees from infection. Variations on the vaccine used in the Thai trial have been investigated previously with apparent success in chimpanzees, yet failure in humans.
Project R&R’s investigation demonstrates the futility of chimpanzee use in HIV-vaccine research. The Thai partial success should not deflect attention from the myriad vaccines (around 100 vaccines tested in over 200 human trials) that have shown great promise in chimpanzees only to fail in humans. The Thai vaccine trial adds no validity to arguments that chimpanzees are necessary or helpful in AIDS vaccine testing.
The case for human-relevant investigations was echoed by AIDS vaccine expert, clinical virologist Scott Hammer, M.D., who commented on the Thai data: “The positive results point to the crucial role of human testing in the development of any vaccine…human immune system variability or virus diversity can’t really be mimicked by any of the currently used laboratory animal models.”
The Thai vaccine’s limited success underscores the need for alternatives to chimpanzees and other animals in vaccine development.