As described in the subsection entitled, “New Accounting Pronouncements – Recently Adopted”, in Note 1 of Notes to Financial Statements of this Form 10-K, we adopted Topic 842 as of January 1, 2019. Prior period amounts have not been adjusted and continue to be reported in accordance with historical accounting under Topic 840.

We have an operating lease for our office space at 149 Commonwealth Drive, Menlo Park, California, or the Menlo Park Lease, that was due to expire in January 2020. On September 10, 2019, we amended this lease agreement to extend the lease term by two months to the end of March 2020. The amendment to the Menlo Park Lease is treated as a modification of the existing lease agreement, and the right-of-use asset and corresponding operating lease liability have been remeasured based on the present value of remaining lease payments over the remaining extended lease term, using the discount rate applicable as of the adoption date. Since the operating lease is a net lease, as the non-lease components (i.e., common area maintenance) are paid separately from rent based on actual costs incurred, such non-lease components were not included in the right-of-use asset and liability and are reflected as an expense in the period incurred.

In April 2019, we entered into an operating lease agreement for office space located at 3 Sylvan Way, Parsippany, New Jersey, or the New Jersey Lease. The initial term of the New Jersey Lease is 11 years with an option to extend for an additional five years and a one-time option to terminate the New Jersey Lease without cause as of the 103^rd month anniversary of the commencement date of the lease. The New Jersey Lease commenced on October 1, 2019, upon our control of the office space on that date. Based on the initial term of the New Jersey Lease of 11 years, the right-of-use asset and corresponding operating lease liability was approximately $2,356,000, which represented the present value of lease payments over the initial lease term, using an incremental borrowing rate of 8% based on information available as of October 1, 2019. Under the New Jersey Lease, we are also obligated to pay certain variable expenses separately from the base rent, including electricity and common area maintenance. Such costs will be expensed in the period they are incurred.

As of December 31, 2019, the remaining lease terms for the Menlo Park Lease and New Jersey Lease ranged from 3 months to approximately 10.8 years. The discount rates used to determine the lease liabilities for the Menlo Park Lease and the New Jersey Lease ranged from 5% to 8%.

The components of lease costs included in operating expenses for the Menlo Park Lease and the New Jersey Lease on our statements of operations were as follows:

	Year Ended December 31,
(In thousands)	2019		2018		2017
Operating lease costs	$	783	$	678	$	661
Variable lease costs⁽¹⁾	17		31		35
Total lease costs	$	800	$	709	$	696

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Variable lease costs represent non-lease components, such as common area maintenance charges.

In October 2019, we entered into an operating lease agreement for office space located at 919 East Hillsdale Boulevard, Foster City, California, or the Foster City Lease. The initial term of the Foster City Lease is 87 months with an option to extend for an additional five years. We have not yet occupied the space as it is being renovated for our use. The Foster City Lease term commences upon the earlier of the date of completion of the construction work or the date upon which we occupy and use the space for its intended purpose. The purpose of the Foster City Lease is to replace our current leased premises at 149 Commonwealth Drive, Menlo Park, California (see above).

Since we do not yet have control of the office space located in Foster City, as defined by Topic 842, during the construction period and do not expect to gain control of the space until on or near the construction completion date, we will not record a right-of-use asset and corresponding lease liability until we occupy the space, which we expect to occur by mid-March 2020, upon which the Foster City Lease will commence. Upon the commencement of the Foster City Lease, the aggregate minimum future lease payments for the initial lease term is approximately $4,400,000, net of a three-month rent abatement period, and subject to scheduled annual increases. Under the Foster City Lease, we are also obligated to pay certain variable expenses separately from the base rent, including taxes and common area maintenance. Such costs will be expensed in the period they are incurred. We have not recognized a right-of-use asset or aggregate lease liability as of December 31, 2019 for the Foster City Lease as the underlying assets were unavailable for use by the Company at any time in the period ended December 31, 2019.

The undiscounted future non-cancellable lease payments under the Menlo Park Lease, the New Jersey Lease and the Foster City Lease as of December 31, 2019 were as follows (in thousands):

2020	$	713
2021		913
2022		938
2023		962
2024		987
Thereafter		3,762
Total lease payments		8,275
Less: undiscounted lease payments related to Foster City Lease		(4,427	)
Less: imputed interest		(1,294	)
Total	$	2,554