Cambridge-based King Street Properties has sold its 200 Cambridgepark Drive office and lab complex for $165.5 million after successfully leasing up the vacant former Pfizer labs to a new generation of life science tenants in just 18 months.

King Street will remain the building operator for the new owner, a fund managed by Morgan Stanley Real Estate Investing.

King Street bought 200 Cambridgepark Drive in July 2014 from Pfizer for $40 million after the pharmaceutical giant put five Alewife buildings on the market and relocated employees to Kendall Square. The developer spent approximately $44 million renovating the buildings, adding new entrances, building systems, tenant improvements and common area amenities.

The six-story, 221,676-square-foot 200 Cambridgepark Drive is now 99 percent leased to six tenants including Celgene, Amgen, Unum Therapeutics and Enumeral Biomedical.

The disposition of 200 Cambridgepark Drive will enable King Street to expand development activity including its 91,000-square-foot spec building at 115 Hartwell Ave. in Lexington, Principal Thomas Ragno said in a statement.

King Street Properties will retain ownership of 87 Cambridgepark Drive, which it also acquired from Pfizer in 2014 for $14.8 million.