Genzyme (again) turns down Sanofi-Aventis

CAMBRIDGE, Mass. — Biotech company Genzyme still is saying “no thanks” to French drug maker Sanofi-Aventis’ tender offer of $18.5 billion, or $69 per share, to acquire it, saying the offer “substantially undervalues” the company.

The offer has been extended until Jan. 11, Genzyme said.

Sanofi has sought to buy Genzyme since August. Genzyme, based in Cambridge, Mass., specializes in treatments for rare genetic disorders, such as Fabry disease and Gaucher disease.