Bristol-Myers Squibb (BMS) has announced an offer of $60 per share, or roughly $4.5 billion, for the acquisition of ImClone. BMS already owns approximately 17% of ImClone’s shares.

The proposition represents a 30% premium over ImClone’s stock price at close on July 30, according to a company statement. “Bristol-Myers Squibb is the natural partner for ImClone as we possess the knowledge base and resources to advance the company’s growth over the long-term, not only with respect to Erbitux, the important cancer therapy we jointly commercialize, but also in terms of developing ImClone’s pipeline assets,” said James Cornelius, chairman and CEO of BMS.

BMS and ImClone have worked in collaboration for seven years. Erbitux (cetuximab), a cancer drug, brought in $185 million in the US in 2007, and $1.3 billion worldwide, according to ImClone financial data.