U.S. biotechnology firm Genzyme, which is fending off an $18.5 billion hostile takeover bid from France's Sanofi-Aventis, is considering a new deal structure that Sanofi has said it would be open to, The Wall Street Journal reported on Sunday.

Genzyme has been holding internal discussions to consider the use of a contingent value right (CVR), which give shareholders more value if the acquired company hits benchmarks, the Journal reported, citing people familiar with the matter.

This particular CVR would likely be tied to the performance of Genzyme drug Campath, an experimental drug for multiple sclerosis that has already been approved for cancer.

Sanofi has called Genzyme's projection of up to $3.5 billion in peak sales for Campath unrealistic. Genzyme has dismissed Sanofi's $69 per share bid as too low. Sanofi and Genzyme could not be immediately reached for comment.