Shares of Genzyme climbed Tuesday on reports that the biotech drugmaker has agreed to be acquired by French pharmaceutical company Sanofi-Aventis for roughly $19 billion, after nearly nine months of back-and-forth between the two companies. Genzyme investors would receive $74 per share plus the right to additional payments if the company meets certain sales goals, according to people familiar with the deal cited by Reuters. The deal is expected to be announced Wednesday morning, when Genzyme reports its quarterly earnings. The expected announcement would come a day after Sanofi’s $18.5 billion offer to acquire the company expires. Genzyme has repeatedly rejected that offer as too low.