UPDATE 2-Takeda files for diabetes drug approval in U.S.

(Adds details, background and analyst comment)

TOKYO, Jan 4 (Reuters) - Japan's Takeda Pharmaceutical Co Ltd 4502.T said on Friday it is seeking U.S. approval to sell Alogliptin, a diabetes drug the firm hopes to replace Actos as the major earner loses patent protection in 2011.

Shares of Takeda fell 3.7 percent on Friday in a broad sell-off. The stock suffered sharp fall in October after U.S. authorities recommended it stop some clinical trials for one of its most promising drug candidates.

“We are hoping Alogliptin to boost our diabetes franchise, which is a very important field for us,” said Takeda spokesman Toshiyuki Ikeuchi. The approval process is expected to take about a year.

Nomura Securities senior analyst Ryoichi Urushihara said he expects Alogliptin sales to reach 300 billion yen ($2.8 billion) a year during the peak years, which will come some five years after the launch. “I see the drug as very promising,” he said.

Japan’s biggest drugmaker is hard pressed to find a successor drug to its best selling Actos.

The drug generated 336 billion yen in sales for the year ended in March, accounting for 26 percent of the drugmaker’s entire revenue.

Alogliptin, or SYR-322, is in a new class of oral agents for the treatment of type 2 diabetes, called DPP-4 inhibitor, regulating blood glucose levels, and the class also includes Merck & Co's MRK.N Januvia and Novartis AG's NOVN.VX Galvus.

Nomura’s Urushihara, who expects the sales of Alogliptin around the end of this year, said the stock market’s positive reaction would likely to be limited given uncertainties over the approval.

“Safety evaluation is very strict for drugs in this category. There are some possibilities for the approval process would not go smoothly,” he said.

Studies have found evidence that certain diabetes drugs, including Takeda's Actos and Glaxo SmithKline's GLSK.DH Avandia, raise the risk of heart failure.

Takeda also said its joint venture with Abbott Laboratories ABT.N filed with the U.S. Food and Drug Administration for approval for TAK-390MR, used for treating acid-related disorders. (Reporting by Mayumi Negishi and Taiga Uranaka)