By Ben Hirschler
LONDON, Feb 8 (Reuters) - GlaxoSmithKline and Gilead Sciences will vie for business in treating HIV patients next week when both companies unveil clinical trial results at a medical meeting in Seattle.
Most attention is focused on Gilead's next-generation drug bictegravir, a so-called integrase inhibitor similar to GSK's successful dolutegravir that may offer advantages in terms of greater potency and reduced side effects.
GSK plans to defend its patch by highlighting the potential of a new two-drug treatment regimen for controlling the virus behind AIDS, a development that marks a departure from conventional triple drug cocktails.
As dolutegravir has been the mainstay of GSK's HIV business in recent years, investors are nervous about the threat posed by Gilead's competitor, even though next week's bictegravir data is only from mid-stage Phase II testing. The drug is also in final stage Phase III testing.
GSK Chief Executive Andrew Witty said dolutegravir's key attribute was its proven track record in avoiding the HIV virus's potential to develop drug resistance. He described other issues as "peripheral".
"It has an extremely impressive resistance profile," Witty told analysts after reporting fourth-quarter results on Wednesday.
"It is not easy to beat ... in terms of the thing that really matters, I think that dolutegravir remains an extremely impressive molecule."
Results of Gilead's Phase II trial comparing bictegravir with dolutegravir when both drugs are used as part of a drug-drug combination will be presented at the Conference on Retroviruses and Opportunistic Infections in Seattle on Feb. 13.
Detailed findings from two Phase III trials testing GSK's new two-drug combination of dolutegravir and Johnson & Johnson's rilpivirine will also be presented the same day. GSK already said in December that the studies were successful.
GSK sells its HIV drugs through its majority-owned ViiV Healthcare unit, in which Pfizer and Japan's Shionogi hold minority stakes. GSK said Shionogi had made clear it intended to retain its stake in ViiV and its put options had now been removed.
(Editing by Elaine Hardcastle)