Subsequent events

9 Months Ended

Sep. 30, 2021

Subsequent Events [Abstract]

Subsequent events

Subsequent events

On November 4, 2021, the Company completed the separation of its oncology portfolio and programs from its severe genetic disease portfolio and programs into a separate publicly traded company, 2seventy bio. The separation was effected by means of a distribution of all of the outstanding shares of common stock of 2seventy bio on the basis of one share of 2seventy bio common stock for every three shares of bluebird bio common stock issued and outstanding on October 19, 2021, the record date for the distribution. The distribution was effected at 12:01 a.m. on November 4, 2021. On November 3, 2021, in connection with the separation, bluebird bio and 2seventy bio executed a separation agreement, a tax matters agreement, an employee matters agreement, an intellectual property license agreement, and transition services agreements, under which both companies will temporarily provide and receive certain services from each other. These agreements effectuated the separation and govern 2seventy bio's relationship with bluebird bio after the distribution. As a result of the distribution and the separation, 2seventy bio is an independent, publicly traded company, effective as of November 4, 2021.

In November 2021, the Company entered into a lease agreement with Assembly Row 5B, LLC ("Landlord") for office space located at 455 Grand Union Boulevard in Somerville, Massachusetts to serve as the Company's future headquarters. Under the terms of the arrangement, the Company will lease approximately 61,180 square feet starting at an annual rate of $45 per square foot, subject to annual increases of 2.5%, plus operating expenses and taxes. In addition, the Company will be eligible for a tenant work allowance of $160 per rentable square foot of the premises. The lease will commence on the date on which the Landlord tenders possession of the premises to the Company with any tenant work required to be performed by the Landlord substantially completed, which is anticipated to occur in the first quarter of 2022.