The Company enters into lease arrangements for its facilities as well as certain equipment. A summary of the arrangements are as follows:

On September 26, 2016, and as amended on December 31, 2016, the Company entered into a 10 year and 9 month lease, which includes two successive five year renewal options, for its facility in Lexington, Massachusetts, which the Company uses primarily for its cGMP manufacturing, as well as for additional laboratory and office space. Throughout the term of the lease, the Company is responsible for paying certain costs and expenses, in addition to the rent, as specified in the lease, including a proportionate share of applicable taxes, operating expenses and utilities. As required under the terms of the lease agreement, the Company has placed restricted cash of $2.6 million in a separate bank account at December 31, 2018 and 2017.

As of December 31, 2018, the Company has received the $11.4 million of tenant improvement allowances to which it was entitled per the lease for the Lexington, Massachusetts facility; of which $8.5 million, $2.8 million and $0.1 million were received during the years ended December 31, 2018, 2017 and 2016. The lease obligation related to the tenant improvement allowance is amortized over the period from the commencement of tenant improvement construction through to the end of the original lease term.

In April 2015, the Company entered into a lease agreement for an office and laboratory facility in Cambridge, Massachusetts, which commenced in October 2015 with a term of 7.5 years with a five-year renewal option to extend the lease. As required under the terms of the lease agreement, the Company has placed restricted cash of $1.0 million in a separate bank account at December 31, 2018 and 2017.

Future minimum lease payments under the Company’s non-cancelable operating leases as of December 31, 2018, are as follows:

For the Year Ended December 31,	Amount
	(in thousands)
2019	$	5,675
2020		5,846
2021		6,021
2022		6,201
2023		5,236
Thereafter		20,927
	$	49,906

The Company recorded rent expense of $4.9 million, $5.6 million and $1.5 million for the years ended December 31, 2018, 2017 and 2016, respectively.

In the ordinary course of business, the Company may be subject to legal proceedings, claims and litigation as the Company operates in an industry susceptible to patent and other legal claims. The Company accounts for estimated losses with respect to legal proceedings and claims when such losses are probable and estimable. Legal costs associated with these matters are expensed when incurred. The Company is not currently a party to any material legal proceedings.