An experimental treatment for HIV developed by GlaxoSmithKline, Pfizer Inc. and Shionogi & Co. reduced the virus in more people than Gilead Sciences Inc.’s Atripla, the world’s best-selling AIDS medicine.
After 48 weeks of treatment, 88 percent of patients receiving a combination of dolutegravir and two other drugs in a study had undetectable levels of virus in their blood, compared with 81 percent of those getting Atripla, London-based Glaxo (NYSE: GSK) and Shionogi of Osaka, Japan, said in a joint statement Wednesday.
The difference was primarily the result of more patients on Atripla dropping out because of side effects, they said.
The study, dubbed Single, is the second of four late-stage trials to be reported this year that Glaxo plans to use in filing for regulatory clearance of dolutegravir. If approved, dolutegravir would be the second in a new class of HIV medicines called integrase inhibitors that work by blocking the virus’s ability to replicate.
“It’s not going to be a huge success for them overnight, but it is looking good,” said Alistair Campbell, research analyst at Berenberg Bank in London. “The integrase inhibitor market is probably going to be quite competitive.” He recommends buying Glaxo’s stock.
Atripla brought in $3.2 billion of revenue last year for Foster City, California-based Gilead. Merck & Co.’s raltegravir, marketed as Isentress, is the only approved integrase inhibitor. Gilead last month applied for U.S. regulatory approval of its own drug in the class, elvitegravir.
Dolutegravir is being developed by Glaxo and Pfizer’s ViiV Healthcare Ltd. joint venture with Shionogi. Shionogi and ViiV will split earnings from sales of dolutegravir. As Glaxo owns 85 percent of ViiV, it will take 42.5 percent of profit from the drug and New York-based Pfizer will receive 7.5 percent.
Dolutegravir was combined in the trial with abacavir and lamivudine, two approved drugs made by ViiV. Among the 414 patients getting the dolutegravir-based combination, 2 percent quit the trial because of side effects, compared with 10 percent of the 419 who received Atripla.
Forty-one percent of patients on Atripla had nervous-system side effects, compared with 15 percent of those getting dolutegravir, the companies said. The rate of gastrointestinal side effects was the same for both drugs.
Glaxo, the U.K.’s biggest drugmaker, introduced the first AIDS pill, known as AZT or retrovir, in 1987.
[GSK operates its U.S. headquarters in Research Triangle Park, N.C.]