WS Development has scored the largest life science development in Boston since Vertex Pharmaceuticals' landmark Seaport deal in 2011.

Cambridge-based Foundation Medicine has leased 580K SF of office and lab space at 400 Summer St., part of WS Development’s Seaport Square mixed-use development. The 400 Summer project is part of a joint venture with PSP Investments, the developer announced Monday.

Bisnow first reported Foundation’s Seaport Square search in March. The company was interested in as much as 1M SF, according to brokerage documents obtained at the time.

“We are honored that Foundation Medicine has chosen 400 Summer Street for their headquarters,” WS Development President Jeremy Sclar said in a prepared statement. “Boston’s Seaport has come to serve as the city’s hub for forward-thinking employers, residents, and retailers, and now as a global hub of the life sciences sector. No company better represents the power of innovation than Foundation Medicine and we are proud to welcome them to our neighborhood.”

This 16-story lab building was designed by Moris Adjmi Architects in collaboration with Stantec’s Boston office. The 625K SF project will include 30K SF of retail and launch construction of a “grand public stair” to connect Summer and Congress streets.

Construction is expected to start later this year, with occupancy expected by 2023. It's the biggest life science deal in the country's life science mecca since Vertex's 1.1M SF, $1B lease kicked off the construction of Fan Pier.