100 Binney St.(PRNewsfoto/Alexandria Real Estate Equities)

Four venture-backed life science companies have committed to a combined 90,000 square feet at 100 Binney St.

This completes leasing for the 431,000-square-foot office/lab building in Cambridge’s Kendall Square.

Developer Alexandria Real Estate Equities last week announced that Facebook had committed to approximately 130,000 square feet, joining anchor tenant Bristol-Myers Squibb, which leased 208,000 square feet in 2015. The building is expected to be completed in the fourth quarter.

Foghorn Therapeutics, Sigilon Therapeutics, Tango Therapeutics and TCR2 Therapeutics completed the tenant roster by signing leases in August, Alexandria said.

“More than a decade ago, in Cambridge, we pioneered the mega trend of developing and amenitizing urban cluster campuses. Our strategic assemblage, entitlement and development of more than 2 million square feet along the Binney Street corridor laid the groundwork for what has become our second mega campus in Cambridge,” Alexandria CEO Joel Marcus said in a statement.

Alexandria is in pre-leasing for 399 Binney St., a 164,000 square foot speculative office/lab building at its Alexandria Center at One Kendall Square campus which it acquired last year for $725 million. The company said it’s received “multiple proposals” from life science and tech companies for nearly the entire building, which is scheduled for completion in late 2018.