12. Commitments and Contingencies

Operating Leases

In May 2013, the Company entered into a lease for office space in Burlington, Massachusetts. The lease is for a 42-month term with minimum monthly lease payments beginning at $17,588 per month and escalating over the lease term. The Company provided a letter of credit to the lessor in the amount of $98,000 as a security deposit pursuant to the lease agreement to secure its obligations under the lease. During 2015, this letter of credit was reduced to $50,000 pursuant to the original lease agreement.

In July 2015, the Company entered into a first amendment to its existing lease for approximately 4,700 square feet of additional office space (the “Additional Space”) in Burlington, Massachusetts, as well as approximately 6,700 square feet of temporary space to be leased prior to the delivery of the Additional Space (which occurred on May 1, 2016). The amendment extended the term of the original lease through October 31, 2019, contemporaneous with the Additional Space, and also provided the Company with an option to lease an additional 5,400 square feet of office space (the “Option Space”). On September 30, 2015, the Company exercised its option for the Option Space. In addition, the Company has the option to extend the term of a portion or the entire lease space for one additional three-year period. The Company may terminate the amendment for convenience with nine months’ notice upon the occurrence of certain events connected to its clinical stage programs. In addition to the base rent, the Company is also responsible for its share of operating expenses and real estate taxes.

On September 21, 2016, the Company entered into a second amendment to its existing lease for approximately 6,748 additional square feet of rented space located in Burlington, Massachusetts. The lease began October 1, 2016 and expires on October 31, 2017. During October 2016, the Company’s lease payment for this additional space was $18,300 per month in incremental rent. Beginning in November 2016, through October 2017, the Company’s lease payments for the additional space increased to $19,000 per month.

On April 7, 2017, the Company entered into an amendment to its existing lease for approximately 1,471 additional square feet of rented space located in Burlington, Massachusetts and an extension of the current lease term through October 2023. The amendment also gives the Company the option to lease approximately 6,450 of additional square feet beginning in 2018.

Future minimum lease payments under the Company’s lease obligations are as follows:

Year	Aggregate Minimum Payments
2017	$	589,554
2018		1,225,490
2019		1,261,051
2020		1,296,776
2021		1,332,670
2022		1,197,370
2023		990,561
Total	$	7,893,472