VaxGen AIDS Vaccine Fails To Protect Participants From HIV Infection in Thai Clinical Trial
Brisbane, Calif.-based biotechnology company VaxGen on Wednesday announced that late-stage clinical trials of its AIDS vaccine AIDSVAX have failed because they had "no noticeable effect on infection rates" among participants, the San Francisco Chronicle reports (Baker, San Francisco Chronicle, 11/13). The trial, the first HIV vaccine efficacy trial ever held in a developing nation, involved nearly 2,500 injection drug users in Thailand (Kaiser Daily HIV/AIDS Report, 9/24). VaxGen said that the vaccine failed to meet its primary endpoint of preventing HIV infection; the vaccine also failed to meet the secondary endpoint of "slow[ing] the progression of disease among those who received the vaccine but later became infected with HIV," according to a VaxGen release. Participants received a total of seven injections over 30 months: at the beginning of the trial, at one month, six months, 12 months, 18 months, 24 months and 30 months (VaxGen release, 11/12). Three years ago, VaxGen enrolled 2,546 injection drug users from the Bangkok area; half of the participants were given a placebo and the other half were given the vaccine. Participants were extensively counseled in HIV prevention and how to reduce their risk of contracting the virus through injection drug use, the AP/USA Today reports (Elias, AP/USA Today, 11/13). During the 36-month trial, 105 participants in the placebo group tested HIV-positive, compared with 106 participants who received at least one injection of the vaccine (Los Angeles Times, 11/13). Trial results were analyzed by the Bangkok Vaccine Evaluation Group, the CDC, the Fred Hutchinson Cancer Research Center's Statistical Center for HIV/AIDS Research and Prevention and VaxGen (VaxGen release, 11/12).
Other AIDSVAX Trials
The "poor" results were "widely expected" because a previous study of the vaccine in North America had also failed to meet its goals, according to the AP/Wall Street Journal (AP/Wall Street Journal, 11/13). VaxGen in late February announced the results of that trial, in which AIDSVAX reduced the rate of new HIV infections by 3.8% among people who received the vaccine, compared with participants who received a placebo injection. At the time, the company said that the vaccine was effective among African Americans, Asians and other non-white, non-Hispanic volunteers. In a subgroup of 498 non-white, non-Hispanic volunteers, the vaccine appeared to provide protection in the range of 30% to 84%. However, further scientific analysis of the trial results showed "no stronger proof" of the company's original conclusion that the vaccine was more effective in African-American study subjects (Kaiser Daily HIV/AIDS Report, 7/2). Another clinical trial in Thailand is using AIDSVAX in conjunction with Aventis Pasteur's ALVAC in 16,000 HIV-negative volunteers from Rayong and Chon Buri provinces in Thailand. In the five-year trial -- which is run jointly by the Thai Public Health Ministry and the Armed Forces Research Institute for Medical Sciences, a joint research and disease surveillance institute that addresses militarily important infectious and tropical diseases -- AIDSVAX is used as a booster for the ALVAC vaccine (Kaiser Daily HIV/AIDS Report, 7/7).
VaxGen President Donald Francis said that the trial results show "how important it is for the international public health community to redouble the effort to develop an effective vaccine" (Washington Post, 11/13). Francis added, "Although we are disappointed with the outcome, VaxGen and our Thai collaborators have created a model that can be used around the world for advanced clinical research of an HIV vaccine" (VaxGen release, 11/12). Dr. Seth Berkley, president and CEO of the International AIDS Vaccine Initiative, said that the trial is "a very important milestone," adding, "This is really the definitive proof that [testing an AIDS vaccine in a developing country] could be done, that it could be done ethically and done well" (San Francisco Chronicle, 11/13). Warner Greene, director of the University of California-San Francisco's Gladstone Institute of Virology and Immunology, said, "This was an unfortunate but expected failure" because the vaccine's "design was too simplistic to shut down" the virus, according to the Contra Costa Times. Greene added that the trial was "not a complete flop" because researchers will still be able to learn from the study, the Contra Costa Times reports. "We've spent a lot of time figuring out what doesn't work. Each time, that takes us closer to something that has a chance of working" (Silber, Contra Costa Times, 11/13). AIDS Vaccine Advocacy Coalition Executive Director Chris Collins said, "This trial was not a failure because it tested a product and produced a result," adding, "Sometimes the results from those trials will be disappointing, but all of us need to be prepared for the long haul to find a vaccine against the biggest infectious disease killer" (AVAC release, 11/12).
IAVI on Wednesday began human clinical trials in South Africa and Switzerland of another HIV vaccine, according to an IAVI release (IAVI release, 11/12). The vaccine, named HIVA.MVA, has already completed phase I trials in Britain and Kenya and is currently undergoing phase II trials -- which test the safety and effectiveness of the vaccine -- in those two countries. A phase I trial of the vaccine is also underway in Uganda. The vaccine was developed by scientists from the U.K. Medical Research Council's Human Immunology Unit at the University of Oxford and Kenya's University of Nairobi, with funding from IAVI (Kaiser Daily HIV/AIDS Report, 11/4). Berkley said, "By conducting a number of trials of HIVA.MVA simultaneously in Africa and Europe IAVI hopes to reduce the time needed to evaluate the vaccine's potential. A preventive vaccine is the best hope to end the spread of a disease that infects 15,000 men, women and children worldwide every day" (IAVI release, 11/12).
PRI's "The World" on Wednesday discussed the vaccine failure with BBC science correspondent Richard Black (Mullins, "The World," PRI, 11/12). The full segment is available online in Windows Media.