courtesy Steelblue

French drugmaker Sanofi Genzyme will become the largest commercial tenant at the 4.5-million-square-foot Cambridge Crossing development, firmly establishing the 45-acre site as a major life science and tech cluster.

The firm will move 2,700 employees to a pair of new buildings scheduled for completion in late 2021, after leasing 900,000 square feet from developer DivcoWest. The Cambridge Crossing campus will include R&D, medical, commercial and global function employees, Sanofi Genzyme said.

The move also could open a prime location in vacancy-starved Kendall Square. The Cambridge Crossing workforce will include 1,200 employees that currently work at the newly-developed 50 Binney St., the Boston Globe reported. Sanofi signed a 12.5-year lease for 251,000 square feet at that property in 2015 from developer Alexandria Real Estate Equities, as it expanded its headquarters workforce from 900 employees at 500 Kendall Square.

Sanofi has 5,000 Massachusetts employees in 10 locations. The company also leases space at 1 Research Drive in Westborough, where it expanded into 167,901 square feet in 2016, and owns a biomanufacturing facility in Framingham and a drug discovery center in Waltham.

DivcoWest acquired Cambridge Crossing in 2015 for $291 million. The San Francisco developer decided to go spec on the first commercial segment of Cambridge Crossing, a 425,000-square-foot office and lab-ready building, in 2017. The decision paid off with Andover-based Philips North America’s decision to become anchor tenant with a 243,000-square-foot lease in January 2018. Completion is scheduled for 2020.

Limited options for expansion in booming Kendall Square have boosted the prospects for commercial development at the 45-acre site previously known as Northpoint. Three residential towers were built under previous ownership.