Commitments and Contingencies Leases We have non-cancelable operating leases for laboratory space in Burlingame, California with several amendments to expand the facility. Commencing on June 1, 2017, the non-cancelable operating lease for the entire existing laboratory space of a total 10,755 square feet was extended for another 5 years through May 2022. In February 2017, we further amended the operating lease for laboratory space with an additional 721 square feet through May 2022. In April 2017, we renewed our headquarters office lease for 6,900 square feet of office space in Burlingame, California through November 30, 2020 and in June 2017, we amended the lease with an additional 1,190 square feet of office space through November 30, 2020. In addition, we have a non-cancelable operating lease for 3,126 square feet of office space in San Diego, California through September 2019. In June 2019, the San Diego lease was renewed and will expire in February 2025. In October 2018, we signed a short-term lease in Burlingame ("October 2018 lease"), consisting of 5,613 square feet of space. The October 2018 lease has been terminated in June 2019. In April 2019, we signed a short-term lease in Burlingame ("April 2019 lease"), consisting of 1,979 square feet of space through April 2020. In May 2019, we signed another lease in Burlingame ("May 2019 lease"), consisting of 1,346 square feet of space through April 2022. In addition, we have five equipment leases expiring through 2023. Operating lease expense was $240,000 and $469,000 for the three and six months ended June 30, 2019 , which includes $32,000 and $58,000 of short-term lease expense, respectively. The following tables below do not include the October 2018 lease and April 2019 lease since they are no more than 12 months. The renewal of the San Diego lease was not included since the new lease term will not start until October 2019. We also have various equipment operating lease agreements. Supplemental cash flow information, as of June 30, 2019 , related to operating leases as follows (in thousands): Amortization of operating lease $ 411 Cash paid within operating cash flows $ 424 Right-of-use assets obtained in exchange for new lease liabilities $ 112 Supplemental balance sheet information, as of June 30, 2019 , related to operating leases was as follows (in thousands, except lease term and discount rate): Reported as: Operating lease right-of-use assets $ 1,692 Current portion of operating lease liabilities $ 734 Long-term operating lease liabilities 991 Total lease liabilities $ 1,725 Weighted average remaining lease term (years) 2.5 years Weighted average discount rate 5.50% As of June 30, 2019 , we are obligated to make minimum lease payments under non-cancelable operating leases, as follows (in thousands): Year ending December 31, Lease Payments 2019 (remaining of year) $ 464 2020 836 2021 649 2022 313 2023 and after 307 Total lease payments 2,569 Less: imputed interest (226 ) Total lease liabilities $ 2,343 As of December 31, 2018, we are obligated to make minimum lease payments under all of our operating leases as follows (in thousands): Year ending December 31, Lease Payments 2019 $ 835 2020 726 2021 459 2022 194 Thereafter  Total $ 2,214 Purchase Commitments In March 2018, we entered into a standard form of agreement with CRB Builders, LLC (CRB) in connection with the renovation of the Plant. Pursuant to the agreement, CRB will provide pre-construction and construction services in connection with constructing and renovating the Plant to provide approximately 16,500 square feet of new production space, and supporting Fill and Finish and Bio Production processes (the Project). The Project was completed in the second quarter of 2019. In June 2018, we entered into a Strategic Supply Agreement (the Agreement), with Pall Corporation (Pall) for purchase of equipment and consumables to be used in support of our manufacturing requirements, including, but not limited to the Plant. Pursuant to the agreement, we will purchase certain pharmaceutical manufacturing equipment and related services in the aggregate amount of $3.8 million with a seven year consumable purchase obligation in the aggregate amount of approximately $16.5 million . The agreement is subject to customary undertakings, covenants, obligations, rights and conditions. We have incurred $3,286,000 in equipment purchase costs and $997,000 in other purchase costs as of June 30, 2019 .