The Company leases real estate, primarily laboratory, office and manufacturing space. The Company’s leases have remaining terms ranging from less than 1 year to 5 years. Certain leases include one or more options to renew, exercised at the Company’s sole discretion, with renewal terms that can extend the lease from one year to five years. The Company evaluated the renewal options in its leases to determine if it was reasonably certain that the renewal option would be exercised, and therefore should be included in the calculation of the operating lease assets and operating lease liabilities. Given the Company’s current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that any renewal options would be exercised. Therefore, the operating lease assets and lease liabilities only contemplate the initial lease terms. All of the Company’s leases qualify as operating leases.

In July 2019, the Company entered into a sublease agreement with a related party to sublease a portion of its office and laboratory space in Cambridge, Massachusetts (see Note 13). The term of the sublease agreement commenced in July 2019 and ends on the last day of the 24^th calendar month following commencement, with no option to extend. The annual rent for the subleased premises will be approximately $1,200 in the first year and $1,300 in the second year, which is greater than the annual rent owed by the Company to the landlord for the leased premises. The sublessee is obligated to pay all real estate taxes and costs related to the subleased premises, including cost of operations, maintenance, repair, replacement and property management.

As of September 30, 2019, future undiscounted cash inflows under the sublease are as follows:

Year Ending December 31,
2019 (remaining 3 months)	$	307
2020		1,248
2021		633
	$	2,188

The Company concluded that the sublease is an operating lease. Consistent with the Company’s policy election for lessor operating leases, each lease component and its associated non-lease components is accounted for as a single lease component.

The following table summarizes the presentation in the Company’s condensed consolidated balance sheets of its operating leases:

	As of September 30, 2019
Assets:
Operating lease assets	$	11,899

Liabilities:
Operating lease liabilities	$	4,335
Operating lease liabilities, net of current portion		16,844
Total operating lease liabilities	$	21,179

The following table summarizes the effect of lease costs in the Company’s condensed consolidated statement of operations and comprehensive loss:

	For the Three Months Ended			For the Nine Months Ended
	September 30, 2019			September 30, 2019
Operating lease costs	$	1,148		$	3,456
Short-term lease costs		330			1,547
Variable lease costs		716			2,302
Sublease income		(439	)		(439	)
Total lease costs	$	1,755		$	6,866

During the three and nine months ended September 30, 2019, the Company recognized $1,096 and $3,299 of rental expense related to office, laboratory, and manufacturing space. During the three and nine months ended September 30, 2019, the Company made cash payments of $1,647 and $4,935 for operating leases, respectively.

The minimum lease payments for the next five years and thereafter is expected to be as follows (in thousands):

	As of September 30, 2019
2019 (remaining 3 months)	$	1,578
2020		6,302
2021		6,461
2022		6,390
2023		5,158
2024 and thereafter		—
Total future minimum lease payments	$	25,889
Less: interest		(4,710	)
Present value of operating lease liabilities	$	21,179

As of September 30, 2019, the weighted average remaining lease term was 4.12 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 11%.

The future minimum lease payments under the Company’s operating leases as of December 31, 2018, were as follows (in thousands):

	As of December 31, 2018
2019	$	6,342
2020		6,120
2021		6,221
2022		6,372
2023		5,158
2024 and thereafter		—
Total future minimum lease payments	$	30,213

During the three and nine months ended September 30, 2018, the Company recognized $1,093 and $3,299 of rental expense, respectively, related to office, laboratory, and manufacturing space.