GlaxoSmithKline's already fast-growing HIV drug business has received an important boost with the success of two major clinical studies testing a new two-drug treatment regimen to control the virus that causes AIDS.

The approach is a departure from conventional triple drug cocktails that can cause troublesome side effects, especially among older patients who make up a growing proportion of those treated for the disease.

Antiretroviral therapy has turned HIV from a death sentence into a manageable condition but patients need to stay on treatment for life, so there is a growing focus on making medication as well-tolerated as possible.

GSK has developed the new two-drug cocktail through its majority-owned ViiV Healthcare, in which Pfizer and Shionogi also hold stakes.

Easing back from triple therapy is the opposite approach to that being pursued by HIV market leader Gilead Sciences, which is banking on improving triple regimens, and analysts at Berenberg said it could help GSK gain market share.

Results of the two Phase III studies, announced late on Monday, showed that the combination of GSK's dolutegravir and Johnson & Johnson's rilpivirine worked as well as three- or four-drug regimens.

Dominique Limet, chief executive of ViiV, said the results were "an important milestone in our understanding of how HIV can be treated", since they represent the first late-stage trial evidence for the two-drug approach.

ViiV will release detailed findings from the studies at a medical meeting next year and plans to seek regulatory approval for the new treatment approach in 2017.

It is one of a number of pipeline projects that GSK is banking on to revive its core prescription drug business as new chief executive Emma Walmsley prepares to take over from the end of March.

In all, the company expects important clinical results for between 20 and 30 experimental medicines by the end of 2018.

GSK also announced on Monday it was bolstering scientific expertise on its board by establishing a new science committee, charged with overseeing research.