AstraZeneca responds to FDA on heart drug Brilinta

AstraZeneca has replied to the Food and Drug Administration queries about its key new heart drug Brilinta and remains confident about a marketing application for the product.

The additional analyses of data for Brilinta requested from the FDA focused on interactions between Brilinta and high-dose aspirin, AstraZeneca said on Friday.

The Anglo-Swedish drugmaker suffered a blow last month when Brilinta failed to win approval from U.S. regulators, delaying a vital new product designed to rival Plavix, the world's second-biggest selling drug.

The company said at the time it had received a so-called complete response letter requesting further analyses of clinical trial data but not additional studies.

AstraZeneca is relying heavily on revenue from Brilinta -- which has been approved in Europe -- to offset expiring patents on some of its best-selling medicines, such as heartburn treatment Nexium and Seroquel for schizophrenia.

The blood thinner is a competitor tor Sanofi-Aventis and Bristol-Myers Squibb's Plavix, which the world's second-biggest drug with sales of more than $9 billion a year.

Brilinta, which is also known as ticagrelor, won a 7-1 vote in its favor from a U.S. advisory panel last July, but a perplexing lack of benefit seen in a North American sub-group of patients in a key clinical trial meant a clear passage through the FDA was never guaranteed.

ASPIRIN THEORY

Experts speculated that the lack of effect in U.S. patients might be due to the drug's interaction with aspirin, which is typically given in higher doses alongside treatments such as Plavix in the United States than in Europe.

AstraZeneca said it believed that the new analyses carried out for the FDA "support the hypothesis that the apparent difference in treatment effect observed in the U.S. and non-US patient subsets... is most likely a reflection of an underlying interaction between ticagrelor and higher doses of aspirin."

But it added the difference could also be a play of chance.

Mark Clark, an analyst at Deutsche Bank, said AstraZeneca had acted swiftly in responding to the FDA, though uncertainty over the regulatory outcome in the United States would likely remain an over-hang for the shares.

AstraZeneca's stock was 1.3 percent higher at 0848 GMT, outperforming a flat European drugs sector.

Once accepted by the FDA, AstraZeneca's latest answers will trigger either a Class 1 review, lasting two months, or a Class 2 review, lasting six months.

Brilinta, or Brilique as it will be known in Europe, is designed to prevent dangerous blood clots in patients with serious chest pain or previous heart attacks.

As well as competing with Plavix, which is now off patent in parts of Europe and will lose U.S. patent protection in 2012, it is also a rival for Eli Lilly's and Daiichi Sankyo's newer drug Effient. Effient has so far had slow sales, due to concerns about bleeding risks.

Plavix, Brilinta and Effient all work by stopping blood platelets from sticking together and forming clots that can cause heart attacks and strokes.

(Editing by Kate Kelland, Alexander Smith and Mike Nesbit)