Hiv Vaccine Study May Lift Hopes After Merck, Sanofi Setbacks
The U.S.-funded study of 16,000 volunteers involves a vaccine that combines two older shots developed by Sanofi- Aventis SA and VaxGen Inc.
While scientists arent holding out for a major breakthrough, they are hopeful the data will give them some indication that they are heading in the right direction, said Marie-Paule Kieny, director of the World Health Organizations Initiative for Vaccine Research in Geneva.
The results presented in Bangkok may be the first turning point since 2007, when an attempt by Whitehouse Station, New Jersey-based Merck & Co. was terminated after the shot appeared to boost peoples chances of becoming infected. It was one of several fizzled attempts to slow the spread of AIDS, which infects about 6,800 new people every day.
“I dont think there is a lot of expectation that the efficacy of this vaccine will be very high,” Kieny said in a telephone interview from Oxford, England. “Any hint towards identifying something which is protective in humans would be good news.”
The Thai study looked at whether different infection- fighting strategies devised by Paris-based Sanofi and VaxGen could be combined in a two-pronged approach.
Trojan Horse
The first vaccine, called ALVAC, uses a canarypox virus thats been disabled so as not to cause sickness in humans as a Trojan horse to smuggle three genetic fragments of HIV into the body. Its designed to coax the immune system to issue so-called T-cells to hunt and kill infected cells.
The second shot, called AIDSVAX, contains an HIV protein called gp120 that the virus uses to enter human cells. Its designed to encourage the body to produce neutralizing antibodies to destroy HIV viruses before they infect healthy cells.
Both vaccines failed in previous trials where they were tested separately. Sanofi, which made ALVAC, stopped development of the shot after a study showed it didnt boost the bodys immune system. VaxGen, a venture spun off in 1995 from South San Francisco, California-based biotech company Genentech Inc., ceased development of AIDSVAX in 2003 after a trial showed it didnt prevent people from getting HIV.
The Global Solutions for Infectious Diseases, a South San Franciso-based non-profit organization, acquired the rights to VaxGens shot.
Glimmer of Success
“Many people in the vaccine research field will not be surprised if the ALVAC-AIDSVAX vaccine regimen proves to be ineffective,” the New York-based AIDS Vaccine Advocacy Coalition said in a preview of the trial results e-mailed to Bloomberg. “However, history tells us that the development of any vaccine involves decades of work and a range of disappointments before the first glimmer of success.”
The researchers enrolled volunteers in Thailands Chon Buri and Rayong provinces, which have the nations highest rates of HIV, according to the study Web site. Subjects were given four doses of the ALVAC vaccine and two of the AIDSVAX shot over six months, then monitored for three years. They were also given condoms and advice on safe sex.
An interim analysis in July 2007 showed there were no safety concerns with the vaccines, the researchers said at the time.
The trial was funded by the National Institute of Allergy and Infectious Diseases, the National Institutes of Health and the U.S. Army Medial Research and Materiel Command.