Frank Baldino Jr., who founded Cephalon Inc. in 1987, died Thursday night. He was 57.

A brief statement released by the Frazer-based biotechnology company did not disclose a cause of death.

Baldino had been on medical leave since late August, and the company had recently said that he would not return to his duties in 2010.

J. Kevin Buchi, who'd been the chief operating officer, has been acting as interim CEO.

Cephalon shares closed Thursday at $63.11, up 23 cents.