Photo courtesy of Alexandria Real Estate Equities

A Cambridge biotech will relocate to Watertown after terminating its lease and committing to occupy nearly 73,000 square feet at 99 Coolidge Ave.

Foghorn Therapeutics is the third tenant to lease space at the Watertown project, a redevelopment of the former Mount Auburn Club by National Development and Alexandria Real Estate Equities.

The new lease has an initial base rent of $87 per square foot, according to an SEC filing, and runs for nine years.

In a related transaction, Foghorn agreed to terminate its existing lease with Alexandria at 500 Technology Square, where it had leased 81,441 square feet. The lease had been scheduled to run through September 2028.

Following completion of tenant fitout work, Foghorn is scheduled to occupy the Watertown property in October 2026.

The annual base rent was abated to 45,000 square feet, or $3.9 million, for the first year of the lease which takes effect on July 16, stepping up to $6.3 million in 2026.

The 255,000 square-foot life science development is located at the 6.3-acre former Mount Auburn Club racquet club in Watertown. Alexandria has a 75.7 percent ownership interest in the property, according to its quarterly report. Previous leases were signed by tenants Sonata and Matchpoint.

Leasing activity has remained sluggish in Watertown and the overall inner suburban market, with 66,364 square feet of negative absorption in the first quarter and a 58.2 percent availability rate, according to a recent Colliers report.