Scientists announce that AIDS 'cocktail' is not a cure; triple-drug therapy does lengthen survival timeNov. 18, 1997
Scientists who helped develop the 'cocktail' of three drugs now used widely to keep AIDS at bay in people infected with HIV admitted Thursday it cannot cure the infection.
They said tests showed the AIDS virus still lurks in the immune system cells it infects, even after years of taking the powerful drugs.
'The bad news is we can't yet get rid of the virus entirely. The number of immune system cells that remain infected with HIV declines only very slowly,' said Dr. Robert Siciliano, an associate professor of medicine at Johns Hopkins University in Baltimore.
'But the good news is that as long as people infected with HIV keep taking the triple-drug cocktail, they have an excellent chance of surviving the infection for a long time, without developing symptoms of the disease.'
Tests have shown that triple therapy, using a combination of three different AIDS drugs, can knock the virus down to undetectable levels after two to four months.
The usual regimen consists of two of the first-generation AIDS drugs such as AZT, ddI or 3TC and known as reverse transcriptase inhibitors, plus a protease inhibitor such as saquinavir or ritonavir.
When the results were announced at a big AIDS conference last year, researchers dared to whisper the word 'cure,' although only very softly and tentatively.
Dr. David Ho of the Aaron Diamond AIDS Research Center in New York and his colleagues at first planned to take one of their patients off the drugs, first after 18 months, then after two years.
But they shelved those plans after tests showed the virus was still hiding in the body, and even one infected cell could release enough virus to re-infect a person.
Ho said earlier this year that mathematical models showed the virus could be completely eradicated after three years, but now abandons even this hope in a report in the journal Science.
The Johns Hopkins and Aaron Diamond researchers looked for HIV in 22 patients who had been on the cocktail therapy for as long as 30 months.
People on this cocktail therapy have to take handfuls of pills every day -- many at set times.
The side effects can be very unpleasant and include nausea, so this group was watched very carefully to make sure they took every pill on time.
'We studied patients whose viral loads had been undetectable for prolonged periods of time,' said Dr. Joel Gallant, director of the AIDS outpatient clinical at Johns Hopkins.
Nonetheless, the researchers were able to routinely tease HIV out of 'resting' CD4 cells -- helper T-cells that had been infected but were not in replicative phase.
'The team also showed that when the resting cells were stimulated to reproduce, the AIDS virus also replicated,' said Diana Finzi, a post-graduate student who led the work.
But there was some positive news. While on the triple-drug regimen, all the patients grew healthier, uninfected immune system cells. Also, the virus was not able to replicate -- so it was also not able to mutate into new, drug-resistant forms.
'So this is a strong argument for not taking these patients off triple-drug therapy,' Siciliano said.
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