GSK to buy HIV drugs from Bristol-Myers Squibb for initial $350 mln

It used to dominate the market but ViiV's 2014 sales of 1.5 billion pounds ($2.3 billion) were less than a quarter of the HIV revenue generated by market leader Gilead Sciences.

ViiV will pay an initial $317 million to buy late-stage HIV drug candidates from Bristol-Myers, including a phase III development treatment fostemsavir, plus $33 million for its preclinical assets.

Both deals are subject to a further payment of over $500 million dependent on commercial milestones being met.

GSK said the assets being acquired complemented ViiV's existing portfolio and could be used in combination therapies.

HIV is often treated by mixing at least three medicines together because of the ability of the virus that causes AIDS to mutate and become drug-resistant.

"The addition of two potential first-in-class late-stage treatments and several promising early clinical development programmes strengthens ViiV Healthcare's pipeline and provides us with further new opportunities for growth," said GSK's chief strategy officer David Redfern, who is also chairman of ViiV.

Demand for HIV drugs is helping GSK replace declining sales of its market-leading respiratory medicine Advair is in decline.