9 . Commitments and Contingencies Operating Lease Commitments We lease office space and laboratory facilities under noncancelable operating leases that have terms expiring through October 2026. In March 2017, BridgeBio entered into a three-year agreement to rent 3,900 square feet of office space in Palo Alto, California. In May 2019, the lease was extended by three years through April 2023. The aggregate rent expense under the lease is $2.2 million. In November 2017, Eidos entered into a five-year agreement to rent 4,659 square feet of office space in San Francisco, California. The aggregate rent expense under the lease was $1.7 million. In March 2019, Eidos entered into an amendment to the November 2017 lease and the amended lease commenced on August 2019. In connection with the amendment, Eidos leases 10,552 rentable square feet. The amended Eidos lease is for 87 months and has $6.4 million of future minimum lease payments. In February 2018, QED entered into a thirty-seven-month agreement to rent 1,944 square feet of office space in San Francisco, California. The aggregate rent expense under the lease is $0.6 million. In October 2018, QED entered into a thirty-four-month agreement to rent 10,000 square feet of office space in San Francisco, California. The aggregate rent expense under the lease is $2.6 million. In October 2019, Adrenas entered into a sixty-one-month agreement to rent 11,376 square feet of laboratory facility in Raleigh, North Carolina. The aggregate rent expense under the lease is $1.9 million. We recognize rent expense on a straight-line basis over the noncancelable lease period and record the difference between cash payments and the recognition of rent expense as a deferred rent liability. Where leases contain escalation clauses, rent abatements and/or concessions, such as rent holidays and landlord or tenant incentives or allowances, we apply them in the determination of straight-line rent expense over the lease period. As of December 31, 2019, future minimum lease payments for all noncancelable operating leases with remaining lease terms in excess of one year, are as follows: Amount (in thousands) Year Ending December 31: 2020 $ 2,811 2021 2,515 2022 1,812 2023 1,485 2024 1,272 Thereafter 1,816 Total future minimum lease payments $ 11,711 Total rent expense for the years ending December 31, 2019, 2018 and 2017 was $2.8 million, $1.5 million and $0.4 million, respectively. Milestone Compensation Arrangements with Employees We have performance-based milestone compensation arrangements with certain employees, whose vesting is contingent upon meeting various regulatory and development milestones, with fixed monetary amounts known at inception that can be settled in the form of cash or fully vested common stock of the Company at our sole election, upon achievement of each contingent milestones. As of December 31, 2019, the potential milestone compensation amount under these arrangements is up to $34.0 million. Under these arrangements, there was no compensation expense recognized or liability recorded for the year ended December 31, 2019 because the performance milestones are not considered probable of achievement. Other Research and Development Agreements We may also enter into contracts in the normal course of business with clinical research organizations for clinical trials, with contract manufacturing organizations for clinical supplies and with other vendors for preclinical studies, supplies and other services and products for operating purposes. These contracts generally provide for termination on notice, with the exception of potential termination charges related to one of our contract manufacturing agreements in the event that certain minimum purchase volumes are not met. As of December 31, 2019 and 2018, there were no amounts accrued related to termination charges for minimum purchase volumes not being met. Indemnification In the ordinary course of business, we may provide indemnifications of varying scope and terms to vendors, lessors, business partners, board members, officers and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by us, our negligence or willful misconduct, violations of law, or intellectual property infringement claims made by third parties. In addition, we have entered into indemnification agreements with directors and certain officers and employees that will require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the us to provide indemnification under such agreements, and thus, there are no claims that we are aware of that could have a material effect on our consolidated balance sheets, statements of operations and comprehensive loss, or statements of cash flows. We also maintain director and officer insurance, which may cover certain liabilities arising from our obligation to indemnify our directors. To date, we have not incurred any material costs and have not accrued any liabilities in the consolidated financial statements as a result of these provisions. Contingencies From time to time, we may become involved in legal proceedings arising in the ordinary course of business. We are not currently a party to any material legal proceedings.