SAN FRANCISCO (AP) _ You'd think Gilead Sciences Inc. would be celebrating. Enthusiastic scientists are hopeful its drugs now used to treat people with the AIDS virus might actually protect healthy people from catching it.
In recent days, researchers heartened by a study in monkeys said they would expand tests of the pill Truvada as a possible preventive for use in healthy people who may be at high-risk for HIV.
But instead of touting its drug, Gilead is trying to turn down the excitement. The attitude is partly based on fears that Truvada will be seen as a ``biomedical condom'' that might promote unsafe sex and lead to a backlash against a company that has become a Wall Street darling.
``It is tricky for the company,'' said Mitchell Warren of the nonprofit AIDS Vaccine Advocacy Coalition in New York. ``It is a real political and business dilemma for Gilead.''
Health officials are mindful of the concerns, too, and say the drugs should only be given along with counseling, condoms and regular testing.
Truvada is a combination of two of the company's drugs, Viread and Emtriva, which are approved by the Food and Drug Administration for keeping the AIDS virus from reproducing in the body. Viread, which the FDA approved in 2001, became one of the most popular AIDS treatments on the market, accounting for $779 million in sales last year. The FDA approved Truvada in 2004 and it is expected to exceed $1 billion in sales this year.
Truvada and Viread have been approved for use only by patients with HIV and not as preventive pills for healthy people. However, doctors can prescribe them for so-called ``off-label'' uses and the pills are easily purchased online.
No one knows how many people may be popping the pills as a means of prevention, but Warren and others suspect such use is increasing. They are hearing anecdotes of healthy men taking Viread and Viagra before a night on the town.
Viread alone is so popular that the National Institutes of Health, the Centers for Disease Control and Prevention and the Bill and Melinda Gates Foundation are funding separate human tests around the world to determine if that drug also could be used as a ``prevention pill.''
Some analysts say such off-label use could become a headache for the company, especially if the pills are ultimately found to be ineffective in preventing the disease.
Notably, Gilead isn't deeply involved in those studies, other than to provide Viread for the tests. Gilead officials said the notion that any of their drugs can be used to prevent AIDS is promising but preliminary because much of the scientific data available come from tests on monkeys.
Years of monkey studies with Viread showed partial protection against HIV in healthy primates.
After Gilead developed Truvada as a two-drug option, six macaques were given pills and then exposed to a deadly combination of monkey and human AIDS viruses. Despite 14 weekly blasts of the virus, none of the monkeys became infected. All but one of another group of monkeys that didn't get the drugs did get HIV, typically after two exposures.
``It's premature to speculate on what the actual use of the product might be at this time,'' said Gilead medical affairs vice president James Rooney. ``We really need data from clinical trials to determine what the effectiveness of the pill would be as a preventive.''
Because of the exciting new monkey results, health officials are now making plans to switch one human trial on Viread to the drug combination.
The Viread tests in high-risk healthy volunteers was ethically charged from the beginning and several ran into problems. In Cambodia in 2004, local sex workers demanded free health care and compensation if any of the volunteers became infected. Cameroon government officials scuttled a test there in 2005 over allegations of improper volunteer recruitment.
Protesters in Bangkok trashed Gilead's booth at the 2004 International AIDS Conference in protest of the CDC-funded study of high-risk drug users in Thailand.
Now, Truvada is becoming even more popular than Viread and it's expected to surpass the older drug's annual sales this year. Last year, Truvada rang up $577 million in sales.
An increasing number of doctors are prescribing Truvada to newly diagnosed patients because it's a single pill taken only once a day, with few side effects.
Viread and Truvada account for 75 percent of the $1.8 billion in revenues last year for a company best known as the developer of Tamiflu, a drug showing promise against bird flu.
Gilead sold to the Swiss giant Roche Holding AG the commercial rights and manufacturing responsibility of Tamiflu in exchange for annual royalties. Still, for a company dedicated to making AIDS drugs, Tamiflu's annual sales are skyrocketing past $2 billion as countries stockpile the flu drug and Gilead is expected to generate almost $400 million this year in royalties.
``Tamiflu is thick, rich and sweet icing on the cake for Gilead,'' said Jason Kantor, an analyst with RBC Capital Markets. ``Because Gilead is absolutely the leading AIDS company.''