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March 31, 2004
HIV vaccine trial to include 20 Ottawa subjects
Unusual test combines two manufacturers' products
Joanne Laucius
The Ottawa Citizen
There are at least 40 clinical trials of HIV vaccines -- both therapeutic and prophylactic -- going on around the world.
While prophylactic vaccines aim to prevent HIV infection, therapeutic vaccines give patients already infected with HIV an immune boost that offers a reprieve from drug treatments. Therapeutic vaccines are relatively new. And the approach used in the Ottawa-Montreal trial is unusual in that it combines products from two vaccine companies.
Researchers started to bring together the two drug vaccine companies, Aventis Pasteur and the Immune Response Corporation, about three years ago, said lead researcher Dr. Jonathan Angel, an infectious disease specialist at the Ottawa Hospital, an associate professor at the University of Ottawa and a scientist at the Ottawa Health Research Institute.
It was difficult to get the two companies to agree in principle. Then, the trial suffered regulatory delays and even more delays when one of the vaccine companies was bought by another.
Now, researchers are set to recruit the 60 subjects for their study, including 20 in Ottawa. A third of the patients in the trial will get both vaccines, another third will get only one vaccine and the last third will get a placebo.
Both of the vaccine components have been tested before. Now they will be tested together, said Dr. Angel. "Each of these is better at inducing one aspect of the immune response."
The combination vaccine is targeted at patients who are HIV-positive, but who have had no detectable HIV in their blood for at least two years, said Dr. Angel. These patients are on drug cocktails that have serious side effects, including digestive upsets and wasting of the arms and legs.
So far, Canadian HIV patients have only been involved in small vaccine studies and in a disappointing and controversial trial of a preventive vaccine. That trial looked at 5,108 gay and bisexual men and 309 high-risk women in Canada, the U.S. and the Netherlands. The results, released last year, concluded that 5.7 per cent of those who had taken the vaccine became infected with HIV, compared to 5.8 per cent of those who had taken a placebo.
In Ottawa, about 1,400 people have been diagnosed as HIV-positive and at least 600 more have not been diagnosed.
Dr. Paul MacPherson, an infectious diseases expert at the Ottawa Hospital, said the outlook for HIV vaccines is guarded, but he is still optimistic.
He believes there are probably several hundred patients at the hospital's HIV clinic who are candidates for the trial.
It wouldn't take resounding success for a vaccine to improve treatment, he said. "I would be excited by any benefit we would see. It would give us a different weapon against the disease."
But some observers say the HIV community is feeling jaded about the potential for HIV vaccines.
For one thing, experts have been predicting for at least two decades that an effective vaccine would be available "in 10 years." That vaccine hasn't appeared and experts are still saying it will take 10 years, said David Thompson, a lawyer who is working on a vaccine strategies project funded by CANVAC (the Canadian Network for Vaccines and Immunotherapeutics) at the AIDS Society of Canada.
"No one believes it anymore," he said. "The attitude is, 'Call me when you have it and you're ready to ship it to the pharmacy.'"
He also has reservations about stopping a successful drug regimen for a vaccine trial. If a patient is on a vaccine that doesn't work or a placebo, that patient has traded something that does work for something that doesn't.
Drug cocktails in recent years have been simplified, he pointed out. Some patients, who may have taken 25 pills a day in the past, take only four pills now, said Mr. Thompson.
Dr. MacPherson said the only patients who will qualify for this trial are those who already have vigorous immune systems. They will also be monitored closely.
"If their immune system shows any decline, they're back on the meds," he said.