Pfizer Agrees to Buy Closely Held Idun

Pfizer Inc. agreed to buy closely held biotechnology company Idun Pharmaceuticals Inc. for an undisclosed amount to supplement its research in areas such as antiviral and cancer therapies.

Pfizer Chief Executive Hank McKinnell is seeking partnerships and smaller acquisitions as patents expire on some of the company’s leading medicines, including Norvasc for high blood pressure and Zoloft for depression. San Diego-based Idun is developing treatments for inflammation and cancer, which will add to the 17 cancer medicines Pfizer has in development.

Pfizer shares rose 9 cents to $26.40 on the NYSE.