Acceleron Pharma has doubled its space in Cambridge.

Colliers Meredith & Grew represented the biopharmaceutical company in two leases totaling 74,816 square feet.

In a new transaction, Acceleron leased the entire 37,000-square-foot 128 Sidney St. building. Acceleron agreed to a long-term lease extension on its existing 37,116-square-foot building located at 149 Sidney St. The landlord, Massachusetts Institute of Technology, was represented in-house by John McQuaid and Patrick Rowe. Specifics of the lease transactions were not disclosed.