Commitments and Contingencies Leases On April 6, 2005, the Company entered into a non-cancellable operating lease (the Lease) for its office, warehouse and laboratory facilities in Exton, Pennsylvania. The lease agreement had an original term of 8 years . On February 17, 2012, the Company entered into an amended and restated lease (the Amended Lease) for an additional term of 10 years through the year 2023. The Lease and the Amended Lease provide for rent payments escalating on a periodic basis. In accordance with ASC 840-20, Operating Leases , the Company accounts for total minimum payments under the lease on a straight-line basis over the life of the lease. The difference between actual rent payments and payments accounted for using the straight-line basis are reflected as deferred rent on the Companys Consolidated Balance Sheets. The Company has the option to renew the lease for an additional 5 years at fair market value. Rental expense totaled approximately $1.6 million for both the years ended December 31, 2017 and 2016. Collaboration with Related Party (Intrexon) The Company is a party to two separate exclusive channel collaboration agreements with Intrexon, a related party. Pursuant to the agreements, the Company is Intrexons exclusive channel collaborator in the research, development and commercialization of products in certain defined fields. The Company is required to pay future royalties, as well as development and commercialization milestones, under these agreements. See Note 14 for additional details. Contractual Obligations The following table summarizes the Companys minimum contractual obligations as of December 31, 2017: Payments due by period ($ in thousands) Total 2018 2019 2020 2021 2022 2023 and thereafter Operating lease obligations (1) 7,451 1,254 1,416 1,471 1,471 1,471 368 Debt obligations (2) 21,968    21,968   Total (3) $ 29,419 $ 1,254 $ 1,416 $ 1,471 $ 23,439 $ 1,471 $ 368 (1) Operating lease obligations are stated based on the Amended Lease agreement for the office, warehouse