Commitments and Contingencies

Operating Leases

In November 2016, the Company entered into an operating lease agreement to occupy 51,000 square feet of laboratory and office space in Cambridge, Massachusetts. This facility serves as the Company’s current corporate headquarters. The lease term began on November 1, 2016 and extends to March 31, 2025. The Company has the option to extend the lease term for one consecutive five-year period, at the market rate, by giving the landlord written notice of its election to exercise the extension at least twelve months prior to the original expiration of the lease term. The Company is recording rent expense on a straight-line basis through the end of the lease term and has recorded deferred rent on the consolidated balance sheets. The lease also provided the Company with a tenant improvement allowance of $0.5 million. The Company recorded the tenant improvement allowance as a deferred lease incentive and is amortizing the deferred lease incentive through a reduction of rent expense ratably over the lease term. Leasehold improvements related to this facility are being amortized over the shorter of their useful life or the lease term. The Company provided the landlord with a security deposit in the form of a letter of credit in the amount of $1.3 million, which is recorded as restricted cash in other non-current assets in the consolidated balance sheets.

As of December 31, 2018, the future minimum lease payments due under the operating lease for the Company’s corporate headquarters are as follows (in thousands):



Years Ended December 31,	Minimum Lease Payments
2019	$	4,260
2020	4,380
2021	4,505
2022	4,633
2023	4,764
2024 and thereafter	6,142
Total future minimum lease payments	$	28,684

The Company leased its former corporate headquarters under an operating lease that was originally set to expire on October 15, 2018. Under this lease, the Company was recording rent expense on a straight-line basis through the end of the lease term and was recording deferred rent on the consolidated balance sheets. The lease also provided the Company with a tenant improvement allowance of $2.8 million. The Company was recording the tenant improvement allowance as a deferred lease incentive and was amortizing the deferred lease incentive through a reduction of rent expense ratably over the lease term. In March 2015, the Company entered into a three-year sublease agreement to lease additional lab and office facilities at the same location as its former corporate headquarters.

On May 19, 2017, the Company entered into a Lease Termination Agreement and a Sublease Termination Agreement (collectively, the “Lease Termination Agreements”) with its landlord related to the leases for its former corporate headquarters. As a result of the Lease Termination Agreements, rental payments for the Company’s former corporate headquarters ceased on May 31, 2017, with the exception of certain space that was utilized through August 31, 2017. The Lease Termination Agreements required the Company to pay an aggregate early termination fee of $0.7 million, which was paid in the second quarter of 2017. This early termination fee was recorded as a component of rent expense. In addition, the remaining deferred rent and deferred lease incentive balances related to the Company’s former corporate headquarters were recognized in full as reductions of rent expense.

During the years ended December 31, 2018 and 2017, the Company recorded total rent expense of $4.0 million and $3.5 million, respectively.

License and Collaboration Agreements

The Company has entered into various license agreements for certain technology. The Company could be required to make aggregate technical, clinical development and regulatory milestone payments of up to $13.4 million and low single-digit royalty payments based on a percentage of net sales of licensed products. As of December 31, 2018, the Company had made $0.2 million in aggregate milestone payments under these license agreements. The Company may cancel these agreements at any time by providing 30 to 90 days’ notice to the licensors, and all payments not previously due would no longer be owed.

The Company has also entered into collaboration agreements with various third parties for research services and access to proprietary technology platforms. Under these collaboration agreements, the Company could be required to make aggregate technical, clinical development and regulatory milestones payments ranging from $12.5 million to $12.9 million per product candidate and low single-digit royalty payments based on a percentage of net sales on a product-by-product basis. As of December 31, 2018, the Company had made $0.5 million in aggregate milestone payments under these collaboration agreements.