BERLIN, Oct 6 (Reuters) - Bayer and partner Johnson & Johnson suffered a setback for blockbuster clot prevention drug Xarelto, with the German company saying a Phase III study had been halted early after the drug showed no efficacy improvements over low-dose aspirin.
The final stage study was evaluating the efficacy and safety of Xarelto, also known as rivaroxaban, for the secondary prevention of stroke and systemic embolism in patients with a recent embolic stroke of undetermined source.
"While bleeding rates were low overall, an increase in bleeding was observed in the rivaroxaban arm compared to the low dose aspirin arm," Bayer, which invented aspirin, said in a statement late on Thursday.
Xarelto was jointly developed by Bayer and J&J, which owns the U.S. rights to the drug.
The drug is already approved for a number of cardiovascular conditions. Prevention of strokes caused by atrial fibrillation, a type of irregular heart beat common among the elderly, is the main profit driver.
Bayer said the trial has no bearing on the positive benefits of Xarelto for other uses for which it is currently licensed.
Xarelto is Bayer's best-selling drug and in 2016 contributed 2.9 billion euros ($3.4 billion) in revenues to its pharmaceutical business. Bayer estimates annual peak sales potential estimate for Xarelto of more than 5 billion euros. ($1 = 0.8549 euros) (Reporting by Victoria Bryan; Editing by Muralikumar Anantharaman)