London — GlaxoSmithKline (GSK) is taking its fight with Gilead Sciences for dominance of the HIV market to the world's leading AIDS conference in July by showcasing detailed results from its new two-drug treatment. The drug makers are touting rival strategies for fighting the AIDS virus, with GSK betting that a shift to using two drugs rather than the standard three will boost its market share, while Gilead sticks with the tried and tested triple approach. Deborah Waterhouse, head of GSK's majority-owned HIV business ViiV Healthcare, aims to overtake Gilead as market leader in the $26bn-a-year HIV market by the mid-2020s, assuming the gamble on two-drug combinations pans out. She has her work cut out. Gilead has a market share of 52% against GSK's 22%, a breakdown that has changed little this year, despite the successful launch of Gilead's new three-drug medicine Biktarvy.