Icagen shares jumped $1.61, or 67 percent, to $4.01 in after hours trading, following the announcement.

"Icagen representatives and Pfizer employees have engaged in preliminary discussions regarding a potential strategic transaction," Pfizer said in a regulatory filing.

The world's largest drugmaker, which owns almost 1.1 million common shares of Icagen, said the company had given it access to due diligence materials.

Pfizer forged in 2007 a research and licensing deal with Icagen, relating to medicines to treat pain and related disorders. The biotech is based in Research Triangle Park, North Carolina.

Pfizer said ongoing talks with Icagen could lead to an extension or amendment of their longstanding agreement. The drugmaker said a strategic transaction could influence or change control of Icagen "by means of a stock or asset acquisition or merger."

Icagen, in a release late on Friday, acknowledged it is engaged in preliminary discussions with Pfizer regarding a potential strategic transaction. But it noted there can be no assurance any agreement will be reached.

(Reporting by Ransdell Pierson; editing by Andre Grenon)