In February 2018, the Company entered into a noncancelable facility lease agreement (the “Lease”) for 9,836 square feet of research and development and office space in Cambridge, Massachusetts. In March 2020, the Company signed a termination agreement for this lease which was determined to be a lease modification that resulted in a reduction of the right-of-use asset and liability of $2.2 million. The lease termination was effective July 31, 2020 at which point the Company no longer had any obligations under the Lease.

In accordance with the Lease, the Company was required to maintain a security deposit and provided a letter of credit to the landlord for $0.2 million, which was subsequently collected in October 2020 following the Company’s release from the security deposit and letter of credit.

In April 2019, the Company entered into a facility sublease agreement (the “Sublease”) for 1,471 square feet of office space in Cambridge, Massachusetts. The term of the Sublease began on June 24, 2019 and terminated on June 30, 2020, and following termination, the Company had no further obligations under the Sublease. The Sublease required the Company to share in prorated operating expenses and property taxes based upon actual amounts incurred; those amounts were considered variable lease costs and, therefore, are not included in the measurement of the lease and are instead recognized to expense as incurred.

In October 2019, the Company entered into a noncancelable facility lease agreement (the “New Lease”) for 34,522 square feet of research and development and office space in Watertown, Massachusetts. The term of the New Lease is 120 months and expires on March 31, 2030. The New Lease has an option to be extended for an additional five years. The New Lease is not reasonably certain to be extended and as such the additional term is not included in the measurement of the lease. The New Lease includes a rent escalation clause, and rent expense is being recorded on a straight-line basis. The Company was eligible for and received a tenant incentive allowance of $5.5 million in 2020 as the tenant improvements were completed. The full allowance amount had been collected from the landlord as of December 31, 2020. In accordance with the New Lease, the Company is required to maintain a security deposit and provided a letter of credit to the landlord for $1.6 million, which is classified as restricted cash on the condensed consolidated balance sheets as of June 30, 2021.

The Company’s finance lease obligations consist of certain property and equipment financed through capital leases.

The components of the lease costs for the three and six months ended June 30, 2021 and 2020, were as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
Operating lease costs	$	524	$	673	$	1,047	$	1,562
Finance lease costs:
Amortization of right-to-use assets, finance leases		193		195		371		356
Interest expense for finance lease liabilities		21		31		37		65
Variable lease costs		153		94		385		201
Total lease costs	$	891	$	993	$	1,840	$	2,184

Supplemental cash flow information relating to the Company’s leases for the six months ended June 30, 2021 and 2020 was as follows (in thousands):

	Six Months Ended June 30,
	2021		2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in (provided by) operating leases	$	1,428	$	(3,905	)
Operating cash flows used in finance leases	$	350	$	309
Financing cash flows used in finance leases	$	37	$	65

Weighted average remaining lease terms and discount rates as of June 30, 2021 and 2020 were as follows:

	Six Months Ended June 30,
	2021			2020
Remaining lease term:
Operating lease	8.84 years			9.80 years
Finance lease	2.68 years			3.30 years
Discount Rate:
Operating lease		10.50	%		10.50	%
Finance lease		8.51	%		7.9	%

The undiscounted future lease payments for operating and finance leases as of June 30, 2021, were as follows (in thousands):

Fiscal Year	Operating Leases			Finance Leases
2021 (excluding the first and second quarter)	$	1,262		$	588
2022		2,581			924
2023		2,659			710
2024		2,732			194
2025		2,814			—
Thereafter		12,925			—
Total minimum lease payments		24,973			2,416
Less amounts representing interest or imputed interest		(8,852	)		(233	)
Present value of lease liabilities	$	16,121		$	2,183