(Updates to midsession)

TOKYO, Nov 28 (Reuters) - Japanese stocks lost steam after opening higher on Wednesday, as automakers such as Toyota Motor Corp <7203.T> slipped into reverse on lingering currency concerns, with the dollar still on track to log its biggest one-month fall against the yen since early 2000. The Nikkei average <.N225> finished the morning session down 0.3 percent or 43.40 points at 15,179.45, after opening 0.3 percent higher following a rise on Wall Street.

The broader TOPIX index <.TOPX> shed 0.1 percent to 1,477.39, having also started the day in positive territory.

But Astellas Pharma Inc <4503.T> provided some support to the market after the drugmaker said on Tuesday it would buy U.S. biotech company Agensys Inc for $387 million to boost its antibody research and development for cancer treatments. [ID:nT274526] (Reporting by Aiko Hayashi; Editing by Hugh Lawson) (([email protected]; +81-5473-3714; Reuters Messaging: [email protected]))

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