SEATTLE Full details from a pivotal trial of Gilead Sciences Inc experimental Quad HIV pill show that it caused fewer adverse side effects than the company's current three-drug pill, Atripla.
Gilead said last year that the trial had met its goal of showing that the four-drug Quad worked as well as Atripla in controlling levels of the virus that causes AIDS.
The safety data, presented here on Wednesday at the Conference on Retroviruses and Opportunistic Infections, showed that patients on Atripla had significantly higher rates of dizziness, abnormal dreams, insomnia and rash, compared with the Quad. The experimental pill did result in higher rates of nausea, 21 percent vs 14 percent.
The study found that at 48 weeks of treatment, 88 percent of Quad patients, compared with 84 percent of Atripla patients, achieved target levels of HIV virus.
Discontinuation rates were similar for both arms of the study, said Dr. Paul Sax, clinical director of the division of infectious diseases at Brigham and Women's Hospital in Boston and the study's lead investigator.
He said 1.4 percent of patients in the Quad group dropped out due to kidney abnormalities, while 1.4 percent of the Atripla group discontinued due to rash.
Dr. Sax said the median level of serum creatinine increase -- a measure of renal toxicity -- was 0.14 milligrams per deciliter for the Quad arm of the study, which was below the level of 0.4 mg/dL which would have been a safety concern.
On the issue of whether it would make sense to eventually switch patients from Atripla to the Quad, he said "it looks like a switch would be virologically safe and maybe associated with fewer central nervous system side effects."
The Quad is seen as key to Gilead's continued dominance of the market for HIV drugs. It combines experimental integrase inhibitor elvitegravir and boosting agent cobicistat with Truvada, a pill consisting of Gilead's older HIV drugs Emtriva and Viread.
Most of the company's current drug sales, which totaled $8.1 billion last year, come from Atripla, a once-daily pill that combines Truvada with Bristol-Myers Squibb's Sustiva.
With the Quad, which is currently under review by U.S. regulators, Gilead owns all of the components.
Full results from another successful trial comparing the Quad to a combination of ritonavir-boosted Reyataz, a protease inhibitor sold by Bristol-Myers, and Truvada, will be presented at the Seattle conference on Thursday.
The Food and Drug Administration is due to decide by August 27 whether to approve the four-drug HIV pill.
(Reporting By Deena Beasley; Editing by Tim Dobbyn)