Boston-based Samuels & Assoc. has landed its first office tenant at the Van Ness, its 550,000-square-foot mixed-use project rising at 1325 Boylston St. in Boston’s Fenway neighborhood.

Cambridge-based health care risk manager CRICO leased 45,000 square feet in the 237,000-square-foot office building, which is being built on speculation. All 130 employees will relocate from its 101 Main St. office in Cambridge upon the building’s completion later this year, spokesman Missy Padoll said.

The office complex is part of a $250-million mixed-use project that includes 200,000 square feet of retail space and 172 luxury apartments with rents starting in the low $3,000s.

Samuels & Assoc. is seeking to recruit tech and creative companies to a new class A office cluster near Fenway Park by offering lower rents than East Cambridge and the Seaport. The Boston-based developer also is planning a major renovation of the Landmark Center following the departure of Blue Cross Blue Shield, which is vacating 380,000 square feet of office space this summer. As part of that project, the 380,000-square-foot parking garage will be demolished and up to 550 residential units and 180,000 square feet of retail will be added, including a Wegmans supermarket.

Founded in 1976, CRICO provides malpractice insurance and claims management services to physicians affiliated with Harvard medical institutions.