Commitments and Contingencies Lease Obligations In January 2018, the Company entered into an operating sublease arrangement to lease approximately 40,765 square feet for its office and research development space at 620 Memorial Drive, Cambridge, MA 02139 from February 2018 to September 2025. The Company maintains an additional separate operating lease for office and laboratory space that is scheduled to expire in 2020 . The leases require security deposits, which the Company has primarily met with letters of credit from a financial institution that are secured with cash on deposit. In June 2018, the Company entered into a sublease arrangement with a third party to lease space subject to an operating lease that is scheduled to expire in 2020 . The future minimum rental payments to be received under this agreement total $0.3 million and are equivalent to the minimum payments due from the Company to the landlord. The Company recorded rent expense of $0.7 million and $2.0 million for the three and nine months ended September 30, 2019 , respectively. Rent expense for the three and nine months ended September 30, 2019 is net of sublease rental income of $0.1 million and $0.4 million , respectively. Rent expense totaled $0.8 million and $1.5 million for the three and nine months ended September 30, 2018 , which is net of sublease rental income of $0.1 million in both periods. The minimum aggregate future lease commitments, exclusive of any offsetting sublease rental payments, at September 30, 2019 , are as follows (in thousands): Twelve month period ending September 30, Amount 2020 $ 3,187 2021 2,951 2022 3,040 2023 3,131 2024 3,225 Thereafter 3,321 $ 18,855 Collaboration Agreement with Sacco S.r.l. In July 2019, the Company entered into a Collaboration Agreement with Sacco S.r.l. ("Sacco"), an affiliate of one of the Companys existing contract manufacturing organizations, pursuant to which and subject to certain exceptions for pre-existing products for pre-existing customers, Sacco will manufacture and supply single strain, non-genetically modified microbes intended for oral delivery or oral use in pharmaceutical products exclusively for the Company for a period of five years . Sacco may terminate the agreement if the provision of manufacturing services has been, or is scheduled to be, inactive for a period of six consecutive months. The Company has agreed to pay Sacco an aggregate of 3.0 million , 0.6 million annually, during the exclusivity period. The Company recognized 0.6 million in expense associated with this agreement during the three months ended September 30, 2019 . Equipment Funding Arrangement In July 2019, the Company entered into an arrangement with one of its external manufacturing partners providing the Company with priority access to future manufacturing services which will be rendered using certain dedicated equipment. In return for such access, the Company committed to provide funding for the purchase of the dedicated equipment in an aggregate amount of 0.8 million , 0.4 million of which to be paid upfront and, subject to the manufacturer's installation and qualification of the equipment, an additional two installments of 0.2 million will be paid in January and April 2020. Biose Industrie On February 15, 2018, the Company entered into an Exclusivity and Commitment Agreement with Biose Industrie (Biose), a French corporation, in which Biose has agreed to exclusively manufacture certain microbial biotherapeutic products for the Company and reserve agreed upon manufacturing resources to conduct manufacturing runs for such products. Under the terms of this agreement, the Company agreed to annual fees in the mid-six digits in consideration of both exclusivity for the manufacture of monoclonal microbials and for a set minimum number of manufacturing runs per year. Exclusivity fees paid and any minimum commitments are expensed as incurred. The Company has agreed to pay an exclusivity fee of $0.3 million per year. Litigation and Other Proceedings The Company may periodically become subject to legal proceedings and claims arising in connection with on-going business activities, including claims or disputes related to patents that have been issued or that are pending in the field of research on which the Company is focused. The Company is not a party to any material litigation and does not have contingency reserves established for any litigation liabilities. In April 2019, the United States Patent and Trademark Office ("USPTO"), granted a third party petition to initiate a post-grant review of a patent issued to the University of Chicago, to which the Company has an exclusive license from the University of Chicago. Although the Company believes that the subject patent is valid, there is a possibility that the USPTO could invalidate the patent or require the University of Chicago to narrow the claims contained in the patent. Under the terms of the license agreement, the Company is responsible for reimbursing the University of Chicago for patent defense costs.