UPDATE 2-OSI profit falls on charges from Astellas bid

* Q1 profit $0.08

* Revenue up 13.7 pct to $106.6 mln

* OSI share of Tarceva revenue $92 mln, up 9.5 pct (Adds CEO outlook, comment)

NEW YORK, April 22 (Reuters) - OSI Pharmaceuticals Inc OSIP.O, which has been fending off a hostile takeover bid by Japan's Astellas Pharma Inc (4503.T), reported much lower first quarter profit on Thursday as results were hit by costs associated with the tender offer.

OSI posted a net profit of $4.9 million, or 8 cents per share, compared with a profit of $16.4 million, or 28 cents per share, a year ago.

The results included $11 million in costs connected with the unsolicited Astellas bid and an $8 million impairment charge associated with an investment in a company that went public, OSI said.

"Clearly our first quarter results have been impacted both financially and strategically by the unsolicited $52 per share offer from Astellas," Chief Executive Colin Goddard told analysts on a conference call.

Astellas offered OSI shareholders $52 per share last month in a deal that would total $3.5 billion. OSI rejected the bid as far too low and its shares have been trading above the offer price since, with analysts saying they expect either a higher offer from the Japanese drugmaker or a rival bidder.

OSI management declined to take questions about the hostile takeover attempt, but said several parties in addition to Astellas were engaged in due diligence.

Revenue for the quarter rose nearly 14 percent to $106.6 million, shy of Wall Street estimates of $115 million, according to Thomson Reuters I/B/E/S.

The company said it expects full year revenue to increase 17 percent and reach $500 million.

Revenue from OSI's share of the cancer drug Tarceva was $92, an increase of nearly 10 percent. OSI co-markets Tarceva with Swiss drugmaker Roche Holding AG (ROG.VX), which reported worldwide sales of $308 million for the quarter.

OSI shares rose to $58.90 in extended trading from their Nasdaq close at $58.66. (Reporting by Bill Berkrot; editing by Andre Grenon, Bernard Orr)