Bristol Myers Squibb won’t be sharing its future Cambridge Crossing home, leasing up the remaining portion of the nearly 480K SF under-construction building.

The pharmaceutical giant is expanding its initial 360K SF lease at DivcoWest’s 250 Water St., securing the entire footprint with an additional 113K SF, the developer announced Thursday. The deal means four of the six buildings are already fully leased at the 43-acre site at the Boston, Cambridge and Somerville borders.

“We are thrilled that Bristol Myers Squibb chose 250 Water Street as a key research and development site to support their mission to discover, develop and deliver innovative medicines that help patients prevail over serious diseases,” DivcoWest Managing Director Mark Roopenian said in a statement. “We’re proud to be creating best-in-class space at Cambridge Crossing where the top leaders in the industry can pursue cutting-edge research and create life-changing treatments.”

Financial terms of the lease weren’t disclosed. The extension was executed in the neighborhood where average asking rents for life sciences tenants can reach $115 per SF.

The building is expected to deliver in 2022. Philips North America and neuroscience company Cerevel Therapeutics have leased up the 22 Jacobs St. building at Cambridge Crossing, while Sanofi will consolidate its workforce at 350 and 450 Water St., DivcoWest said.

Two buildings totaling 600K SF remain at the project: 441 Morgan Ave. and 121 Morgan Ave., with 441 Morgan expected to break ground this spring. The campus is rising alongside the under-construction MBTA Green Line, which will include two new stops near the neighborhood.

Cambridge Crossing, purchased by San Francisco-based DivcoWest for $291M in 2015, will also include 11 acres of open space, more than 2,400 residences and retail.

UPDATE, APRIL 16, 5 P.M. ET: This story has been updated with a new statement from DivcoWest Managing Director Mark Roopenian.