Alexandria Real Estate Equities has a full tenant roster at its latest Kendall Square development before it even opens.

Four venture-backed biotech startups will join Facebook and Bristol-Myers Squibb at the REIT’s 431K SF 100 Binney St., which is scheduled to officially hit the market in Q4. The company is constructing the building as part of its 2M SF Alexandria Center in Cambridge’s Kendall Square neighborhood.

Foghorn Therapeutics, Sigilon Therapeutics, Tango Therapeutics and TCR2 Therapeutics are each expected to take about 22K SF in the building, the Boston Business Journal reports.

"Robust demand for Class-A office/laboratory space on Alexandria's flagship campuses in Cambridge, in part, continues to drive our strong internal growth," Alexandria CEO Joel Marcus said in a prepared statement.

Bristol-Myers Squibb will use 208K SF in the building as a drug-discovery center where 300 employees will focus on genetic diseases. Facebook announced last week it was taking a three-floor lease for 130K SF in the building.

With 100 Binney St. fully leased, Alexandria will focus on pre-leasing 399 Binney St., a 164K SF office/lab building it is developing nearby at the Alexandria Center. The company owns and operates 6.3M SF in Greater Boston, representing 22% of its 28M SF asset base. In August, Mizuho Securities analyst Rich Anderson said this posed a geographic concentration risk.

Marcus later responded that the company’s five-year plan included a future that was not as heavily centered around Boston.