6. Commitments and Contingencies Lease Agreements The Company recognizes rent expense on a straight-line basis over the term of its operating leases commencing on the date the Company takes possession of the leased property. Tenant improvement allowances which are considered to be lease incentives from the lessor are recorded as deferred rent and amortized as a reduction of rent expense over the term of the lease from the possession date. In March 2015, the Company entered into a 5.5-year, non-cancelable operating lease for office space in Rockville, Maryland. The lease commenced in April 2015, and expires in September 2020. The Company has options to extend the lease for up to 6 years. Initial monthly payments required under the lease were $24 beginning in October 2015 and escalate annually in accordance with the lease. In September 2015, and again in November 2015, the Company amended its operating lease in Rockville, Maryland to include additional office and laboratory space and extend the term of the lease for its existing space to October 2020. The lease for the additional space commenced in April 2016, and has a 5-year term expiring in March 2021. The Company has options to extend the lease for the additional space to be coterminous with the Companys existing lease at that facility. Monthly payments under the lease escalate annually in accordance with the lease agreement. The Company received a $0.3 million tenant improvement allowance from the landlord which will be deferred and amortized on a straight-line basis as a reduction of rent expense over the term of lease. In January 2016, the Company entered into a 7.5-year, non-cancelable operating lease for additional office space in Rockville, Maryland. The lease commenced in February 2016, and expires in September 2023. Monthly payments under the lease began seven months from the commencement date and escalate annually in accordance with the lease agreement. The Company received a $0.7 million tenant improvement allowance from the landlord which will be de