The lease was a 10-year, early renewal and expansion at 300 Third St. provided for under an option in the original lease, John Hennessey, with GVA Thompson Doyle Hennessey & Stevens' Boston office, tells GlobeSt.com. The firm then sublet 22,300 sf of that space for four years to Momenta Pharmaceuticals, a life sciences company. Momenta will move into the space in March.

Archemix, which signed the initial lease on 34,014 sf last year, expects to need all 67,451 sf in the near future as the market's lab space continues to tighten. "It just shows how tight the lab market is," Hennessey says. "Tenants are in a defensive mode as far as controlling their future lab needs."

He says Archemix, which now leases the first and second floors of the four-story building, expects to grow into the space once the four-year sublease to Momenta expires. Terms of the lease were not available but Hennessey says lab space in the Cambridge market generally leases in the low $50 per sf triple net range.