MPM Capital has signed the first office lease at 450 Kendall St. in Cambridge, a speculative office building developed by BioMed Realty.

The venture capital firm, which specializes in the biomedical industry, will relocate from Boston’s Hancock Tower in April and expand from 11,000 to 14,511 square feet. It will occupy space on the fourth and fifth floors, with outdoor terraces overlooking Broad Canal. The offices include incubation space for start-ups. In the past two years, MPM has incubated seven companies in its Boston offices.

"MPM Capital is excited to be moving back to Kendall Square’s thriving and vibrant life sciences scene, where we will continue our role as a catalyst of this important ecosystem," said Todd Foley, managing director, MPM Capital, in a statement.

The 60,117-square-foot 450 Kendall St. is the first speculative office building built in Cambridge since 2001. MPM is the first tenant.

Transwestern RBJ’s Steven Purpura, managing partner and Northeast market leader, and Eric Smith, partner, represented BioMed Realty. Transwestern RBJ’s John Barry, partner, and Jeff Landers, assistant vice president, represented MPM Capital.

At the close of third quarter, vacancies in Kendall Square had fallen to 6.6 percent, according to Transwestern RBJ research.