Biotech drugmaker Genzyme Corp. says talks between its financial advisers and those of suitor Sanofi-Aventis have expanded to include representatives of both companies.

The Cambridge, Mass., company says the talks focus on potential terms for a deal and include ways to value right for its experimental multiple sclerosis drug called alemtuzumab.

Genzyme shares rose 2 percent in pre-market trading.

French drugmaker Sanofi-Aventis has been pursuing a deal with Genzyme since last summer. Genzyme has rejected Sanofi's takeover bid of $18.5 billion.

Genzyme stumbled last year after regulators uncovered plant manufacturing problems, but the company says Sanofi's offer fails to account for its recovery and pipeline of developing drugs like alemtuzumab.