A new stroke prevention drug developed by Bayer and Johnson & Johnson proved a safe alternative to the standard treatment, lifting their chances of entering a $12 billion plus market, the German drug company said.

A late-stage study called Rocket-AF showed that the Xarelto pill was as good as the established warfarin pill at reducing the risk of strokes due to a form of irregular heartbeat that is common among the elderly, Bayer said on Sunday.

The preliminary results also revealed that patients on Xarelto, an anti-blood-clotting drug also known as rivaroxaban, ran a risk of bleeding that was comparable to those on warfarin.

“The rates of the composite of major and non-major clinically relevant bleeding were comparable,” Bayer said in its brief statement.

The risk of haemorrhaging — a common side effect in anti-clotting drug — was a main focus of the Phase III trial whose participants were in their mid-70s.

Xarelto’s efficacy had largely become evident in previous studies, where it was used to prevent thrombosis in patients bed-ridden after surgery, the company said.

Detailed results of the Rocket-AF trial are scheduled to be presented at the American Heart Association conference in Chicago on Nov. 15.

A Bayer spokesman declined to provide more details ahead of the conference.

Bayer has said it is eyeing more than 2 billion euros ($2.78 billion) in annual sales from Xarelto in a market worth an estimated $12 billion to $15 billion in total, a commercial potential only matched by its cancer treatment Nexavar.

Analysts’ projections of that market range between $10 billion and $20 billion in annual sales.