6. Commitments and Contingencies Purchase Commitments The Company conducts product research and development programs through a combination of internal and collaborative programs that include, among others, arrangements with universities, contract research organizations and clinical research sites. The Company has contractual arrangements with these organizations; however, these contracts are generally cancelable on 30 days notice and the obligations under these contracts are largely based on services performed. Facilities In September 2018, the Company entered into a noncancelable operating lease (the Lease) for approximately 129,846 square feet of space in Brisbane, California (the New Facility). The date on which the Company will become responsible for paying rent under the Lease (the Rent Commencement Date) will be the date the premises are ready for occupancy, currently anticipated to be January 2020. The Lease expires 10 years after the Rent Commencement Date. The Lease grants the Company an option to extend the Lease for an additional 10-year period. Future minimum rental payments under the Lease during the 10-year term are $93.2 million in the aggregate. The Lease further provides that the Company is obligated to pay to the landlord certain costs, including taxes and operating expenses. As of September 30, 2018, the Lease term has not commenced as the Company did not have the right to use or control physical access to the New Facility. In September 2018 t he Company provided a standby letter of credit of $1.9 million as security for its obligations under the Lease. This standby letter of credit together with standby letters on Existing Facilities (as defined below) are classified as long-term assets within restricted cash and other on the balance sheet. The Company currently leases approximately 48,400 square feet of office and lab space in two separate facilities in South San Francisco, California (the Existing Facilities). All of the lease agreements associated with the Existing Facilities expire on or before January 2020. The Company does not plan to cancel the existing lease agreements for its Existing Facilities prior to their respective expiration dates. Future annual minimum lease payments due under the new and existing operating leases at December 31 of each year are as follows (in thousands): Year ending December 31: Amount 1 2018 (three months) $ 531 2019 2,071 2020 5,454 2021 8,461 2022 8,757 Thereafter 70,508 Total $ 95,782 (1) The table above is prepared under the assumption that the Rent Commencement Date at the New Facility starts on January 1, 2020. Rent expense for the three months ended September 30, 2018 and 2017 was $0.6 million and $0.3 million, respectively, and for the nine months ended September 30, 2018 and 2017 was $1.6 million and $1.0 million, respectively. The operating leases require the Company to share in prorated operating expenses and property taxes based upon actual amounts incurred; those amounts are not fixed for future periods and, therefore, are not included in the future commitments listed above. Contingencies From time to time, the Company may have contingent liabilities that arise in the ordinary course of business activities. The Company accrues for such a liability when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. There were no contingent liabilities requiring accrual or disclosure as of September 30, 2018 or December 31, 2017. Guarantees and Indemnifications The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to certain of these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third-party with respect to the Companys technology. The term of these indemnification arrangements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable because it involves claims that may be made against the Company in the future but have not yet been made. The Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Companys request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws, and agreements providing for indemnification entered into with its officers and directors. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity. The maximum amount of potential future indemnification of directors and officers is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with its exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.