US group Genzyme's resistance to Sanofi-Aventis' advances could be starting to thaw, so much so that the firm is reportedly considering entering discussions with the French drugmaker.

While Genzyme has not yet taken the step of formally inviting Sanofi to start the next stage of the takeover process, sources close to the situation have told the Wall Street Journal that the firm seems more willing to enter talks over issues such as price that have thus far proven to be stumbling blocks in the deal.

Whether the two parties can reach an agreement is still anyone's guess, but the fact that Genzyme seems willing to try after months of vigorously resisting the proposed $18.5 billion takeover indicates that the firms' may have turned a corner.

Still, it is unlikely that Genzyme will agree to the current deal on the table, the sources note, particularly as the company believes that the sales potential of key drug Campath (alemtuzumab) is much higher than Sanofi's offer assumes.

By Genzyme's reckoning, leukaemia drug Campath could pull in sales of up to $3.5 billion by 2017 following approval in the multiple sclerosis indication, but Sanofi thinks its potential is much lower, around the $700 million mark, the WSJ notes.

Earlier this month, Sanofi said it would extend its $69.00 a share offer for Genzyme until January 21, after only 0.9% of shares had been tendered by the original deadline.