Image courtesy of The Architectural Team

As the initial residential phase of the Fenway Center air rights project prepares to open this spring, developers received approval to build a pair of office-lab towers totaling 720,000 square feet on a deck above the Massachusetts Turnpike.

Boston Planning & Development Agency directors Thursday approved the project change, which eliminates multifamily housing from Fenway Center phase two. 

Boston-based developer John Rosenthal of Meredith Management brought on IQHQ Inc. as a partner last year and switched to an office-lab strategy for the project, which has been in the works for more than a decade. IQHQ Inc., a San Diego life science REIT, in February completed a $770 million equity raise that it plans to invest in properties in Boston, San Francisco, San Diego and the United Kingdom.

The company made its first local acquisition in February, paying $270 million for 109 Brookline Ave.

The Fenway Center project spans air rights parcels offered up the Massachusetts Department of Transportation. A 22-story, 535,000-square-foot office-lab tower will front on Beacon Street. The 12-story office-lab building, fronting on Brookline Avenue, will wrap around a five-story, 600-car mechanized parking garage.

The Fenway’s proximity to the Longwood Medical Area cluster and Cambridge has made it increasingly attractive to life science development. Samuels & Assoc. recently kicked off its 201 Brookline Ave. project, a 500,000-square-foot office-lab tower, after signing leases totaling 89,000 square feet from venture capital firm Third Rock Ventures and Cambridge-based Tango Therapeutics.

The first phase of Fenway Center is a 312-unit apartment complex at 771 Beacon St. called the Bower, which is scheduled to open in June. That phase is a partnership between Meredith Management, TH Real Estate and Gerding Edlen.