Astellas Pharma Inc. is considering whether to raise or abandon its unsolicited $1.1 billion bid to buy CV Therapeutics Inc. after the company agreed to a higher offer from a rival.

Astellas hasn't ruled out any options, including pursuing the current offer, a spokesman for the country's second-biggest drugmaker said Friday. He asked not to be named, citing company policy.

Chief Executive Officer Masafumi Nogimori, 61, made the hostile bid for CV Therapeutics even after two rejections to bolster a thinning development pipeline and counter dwindling sales as existing medications lose patent protection. Astellas is after the Ranexa chest pain treatment of CV Therapeutics, which agreed Thursday to a $1.4 billion offer from Gilead Sciences Inc.

CV Therapeutics's board rebuffed Astellas' $16-a-share proposal on Feb. 20, saying it "significantly undervalues" the California-based company. The U.S. drugmaker had refused the same approach in November.