Bayer headquarters in Leverkusen Germany.
Drug maker Bayer rose 1.8% after the U.S. Food and Drug Administration granted fast-track status to its experimental prostate-cancer therapy. Reuters

Bayer drug Xarelto, or rivaroxaban, a standard blood thinning therapy, reduced the rate of heart attacks, strokes, myocardial infarction, and cardiovascular death in a study involving acute coronary syndrome (ACS) patients, the company said late Thursday.

The company said the drug, an oral direct factor Xa inhibitor, was associated with an increased risk of bleeding.

Xarelto, a blood thinner treatment, reduced the rate of heart attacks, strokes and cardiovascular death versus placebo, Leverkusen, Germany-based Bayer said in a statement later that day.

Patients who took Xarelto faced a higher risk of major bleeding, a feared side effect of blood thinners, Bayer said.

Bayer said it intended to present these data as soon as possible at a forthcoming scientific congress as well as to file for market authorization by the end of this year.

In early September, the U.S. Food and Drug Administration recommended against an immediate approval for Bayer AG and Johnson & Johnson’s anti-clotting drug, Xarelto, as a treatment to prevent strokes in patients with atrial fibrillation.

Rivaroxaban, which is marketed in the U.S. under a collaboration with Johnson & Johnson, is FDA approved for prevention of deep vein thrombosis in patients undergoing joint surgery.

The FDA is currently considering the company's application to market the drug for the prevention of stroke in patients with nonvalvular atrial fibrillation.

The agency said data from a late-stage study of more than 14,000 patients, known by the acronym ROCKET, doesn't make it clear how safe Xarelto is, or whether it's as effective as the widely used Warfarin.

Xarelto was approved in July for reducing the risk of deadly blood clots in patients getting knee and hip replacements, a small part of the potential patient pool.

The approval followed a delay of roughly two years due to FDA concerns about the internal bleeding risk.

Having treated thousands of patients with atrial fibrillation and dealt with the tremendous problems of using warfarin and patients having issues with warfarin, I think there's a tremendous unmet medical need for new therapies, panel member Philip Sager, MD, told

An additional patient study could be done, which would cause a long delay before the drug-makers could again seek approval, FDA officials say.

Bayer Healthcare already markets rivaroxaban, a daily pill which works by blocking a clotting protein, in 110 countries around the world.