4. Commitments and Contingencies Future Lease Commitments The Company has entered into certain leasing commitments, for which, right of use assets and right of use liabilities are not reflected on the consolidated balance sheet as the leases have not yet commenced. In November 2019, the Company, together with one of its partners, committed to making $3.7 million in annual rental payments to a clinical manufacturing organization under a lease arrangement for a five-year period following commencement of the lease arrangement. The lease arrangement is expected to commence in the second half of 2020 and all payments will be split equally between the Company and its partner. In May 2020, the Company entered into a lease agreement for a cell therapy manufacturing facility in Framingham, Massachusetts, or the Framingham Lease, for clinical and commercial production of the Companys investigational cell therapy product candidates. The Framingham Lease is expected to commence in the second half of 2020. In connection therewith, the Company has committed to making at least $40.2 million in rental payments over the fifteen-year lease term. In July 2020, the Company entered into a lease agreement for an office and laboratory facility in Boston, Massachusetts, or the 2020 Boston Lease. The 2020 Boston Lease is expected to commence in the first half of 2022. In connection therewith, the Company has committed to making at least $292.5 million in rental payments over a lease term of 152 months. Litigation In the ordinary course of business, the Company is from time to time involved in lawsuits, claims, investigations, proceedings, and threats of litigation relating to intellectual property, commercial arrangements, employment and other matters. While the outcome of those proceedings and claims cannot be predicted with certainty, the Company is not party to any legal or arbitration proceedings that may have significant effects on its financial position. It is not a party to any material proceedings in which any director, member of executive management or affiliate of the Company is either a party adverse to it or its subsidiaries or has a material interest adverse to it or its subsidiaries. Letters of Credit As of June 30, 2020, the Company had restricted cash of $6.3 million representing letters of credit securing the Companys obligations under certain leased facilities, as well as certain credit card arrangements. The letters of credit are secured by cash held in a restricted depository account. The cash deposit is recorded in restricted cash in the accompanying consolidated balance sheet as of June 30, 2020. In addition, in connection with the 2020 Boston Lease, a letter of credit for $10.5 million was issued. Research, License and Intellectual Property Agreements The Company has engaged several research institutions and companies to identify new delivery strategies and applications of the Companys gene-editing technology. The Company is also a party to a number of research license agreements which require significant upfront payments and may be required to make future royalty payments and potential milestone payments from time to time. In addition, the Company is also a party to intellectual property agreements, which require maintenance and milestone payments from time to time. Further, the Company is a party to a number of manufacturing agreements that require upfront payments for the future performance of services. In association with these agreements, on a product-by-product basis, the counterparties are eligible to receive up to low eight-digit potential payments upon specified research, development and regulatory milestones. In addition, on a product-by-product basis, the counterparties are eligible to receive potential commercial milestone payments based on specified annual sales thresholds. The potential payments are low-single digit percentages of the specified annual sales thresholds. The counterparties are also eligible to receive low single-digit royalties on future net sales. Under certain circumstances and if certain contingent future events occur, Vertex Pharmaceuticals Incorporated and certain of its subsidiaries, or Vertex, is eligible to receive up to $395.0 million in potential specified research, development, regulatory and commercial milestones and tiered single-digit percentage royalties on future net sales. Refer to Note 5 for further discussion on the Companys arrangements with Vertex.