Ironwood Pharmaceuticals Inc., which had considered building a new headquarters on the South Boston Waterfront, Route 128, or elsewhere in Cambridge, has instead signed a two-year extension on its lease and taken additional space at its 301 Binney St. site, near Kendall Square in Cambridge.
The extended lease will allow Ironwood, which plans to launch its drug to treat irritable bowel syndrome with constipation in the United States this year, to add 93,000 square feet on the fourth floor of the Binney Street building. It currently uses the building’s second and third floors. The expansion would give it about 300,000 square feet.
Ironwood’s lease was set to expire in 2016.