AstraZeneca's heart drug Brilinta failed to help stroke patients as hoped in a big clinical trial, dealing a blow to company expectations that the medicine could rack up annual sales of $3.5 billion by 2023.

The trial found the blood-thinner was not significantly better than aspirin, the current standard of care, in preventing recurrent attacks in the 90 days after patients suffer a stroke, the British drugmaker said on Wednesday.

The outcome of the study will disappoint investors who had thought there was a good chance of success, since Sanofi's now off-patent drug Plavix previously showed limited benefit in stroke and Brilinta is more potent.

In the event, fewer patients taking AstraZeneca's drug in the trial had a recurrent stroke, suffered a heart attack or died than those on aspirin, but the difference was not statistically significant.

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A positive result would have boosted consensus forecasts for Brilinta, which currently stand at an annual $1.87 billion for 2020, according to Thomson Reuters Cortellis.

AstraZeneca's own projection is that Brilinta could reach sales of $3.5 billion by 2023, making it an important part of a $45 billion revenue target announced by the company as part of its defense against a takeover bid from Pfizer in 2014.

"It's a setback but at this stage we are not providing any new guidance on the overall ($3.5 billion) number," Ludovic Helfgott, head of AstraZeneca's Brilinta business, told Reuters.

Full trial results from the so-called SOCRATES trial will be presented at the May 10-12 European Stroke Organisation conference in Barcelona, he said.

The drugmaker, whose shares bucked a stronger market to trade 0.1 percent lower by 0845 GMT, said preliminary analyzes showed that the safety data from the study was consistent with the known safety profile of Brilinta.

Brilinta is currently approved to reduce the rate of adverse cardiovascular events in patients who have previously suffered a heart attack but AstraZeneca is hoping to expand its use into new areas.

Results from another trial evaluating the medicine in peripheral arterial disease are expected in the second half of 2016.

"The result in SOCRATES has no bearing whatsoever for the rest of the program," said Elisabeth Bjork, AstraZeneca's head of medicines development for cardiovascular and metabolic disease. "We are still very excited about the potential." (Editing by Jane Merriman)

AstraZeneca's heart drug Brilinta failed to help stroke patients as hoped in a big clinical trial, dealing a blow to company expectations that the medicine could rack up annual sales of $3.5 billion by 2023.

The trial found the blood-thinner was not significantly better than aspirin, the current standard of care, in preventing recurrent attacks in the 90 days after patients suffer a stroke, the British drugmaker said on Wednesday.

The outcome of the study will disappoint investors who had thought there was a good chance of success, since Sanofi's now off-patent drug Plavix previously showed limited benefit in stroke and Brilinta is more potent.

In the event, fewer patients taking AstraZeneca's drug in the trial had a recurrent stroke, suffered a heart attack or died than those on aspirin, but the difference was not statistically significant.

A positive result would have boosted consensus forecasts for Brilinta, which currently stand at an annual $1.87 billion for 2020, according to Thomson Reuters Cortellis.

AstraZeneca's own projection is that Brilinta could reach sales of $3.5 billion by 2023, making it an important part of a $45 billion revenue target announced by the company as part of its defense against a takeover bid from Pfizer in 2014.

"It's a setback but at this stage we are not providing any new guidance on the overall ($3.5 billion) number," Ludovic Helfgott, head of AstraZeneca's Brilinta business, told Reuters.

Full trial results from the so-called SOCRATES trial will be presented at the May 10-12 European Stroke Organisation conference in Barcelona, he said.

The drugmaker, whose shares bucked a stronger market to trade 0.1 percent lower by 0845 GMT, said preliminary analyzes showed that the safety data from the study was consistent with the known safety profile of Brilinta.

Brilinta is currently approved to reduce the rate of adverse cardiovascular events in patients who have previously suffered a heart attack but AstraZeneca is hoping to expand its use into new areas.

Results from another trial evaluating the medicine in peripheral arterial disease are expected in the second half of 2016.

"The result in SOCRATES has no bearing whatsoever for the rest of the program," said Elisabeth Bjork, AstraZeneca's head of medicines development for cardiovascular and metabolic disease. "We are still very excited about the potential." (Editing by Jane Merriman)