Genzyme Chief Executive Henri Termeer is set to walk away with nearly $160 million when the sale of his company to French drugmaker Sanofi-Aventis is final - and stands to earn considerably more should Genzyme's multiple sclerosis drug prove as successful as Termeer has predicted.

Termeer is set to receive compensation of $145.9 million from his Genzyme shares, stock options and restricted stock units on completion of the $20.1 billion deal with Sanofi , according to a regulatory filing.

The longtime CEO would also receive $12.5 million in a change of control payment if his employment were terminated with or without cause, according to the filing. Termeer has already said he would leave the company following a brief transition period, which would trigger the additional payment.

In addition to the agreed upon $74 per share price for Genzyme stock, each shareholder will receive one contingent value right (CVR) per Genzyme share, which could increase in value to a maximum $14, primarily based on the company achieving sales milestones for its experimental MS drug Lemtrada.

The CVRs will trade separately on Nasdaq.

If Lemtrada's annual sales eventually hit $2.8 billion and the company reached earlier manufacturing and regulatory goals, Termeer's take would be an additional $62.8 million from his CVRs, according to the filing.

At the time the companies sealed their deal, Sanofi CEO Chris Viehbacher joked that if Lemtrada sales actually got to $2.8 billion he would personally deliver the check to Termeer, along with a bottle of his favorite wine.

Sanofi earlier on Monday said it had extended its offer for all outstanding shares of Genzyme until April 1 from March 16.