The Company leases office space and equipment under agreements classified as operating leases that expire on various dates through 2023. The Company’s most significant active leases as of June 30, 2019 are for office and manufacturing space in Tucson, Arizona, which expire in 2021. The Company also leases a development laboratory space in San Carlos, California, which expires in 2023. The Company’s leases do not include any contingent rental payments, impose any financial restrictions, or contain any residual value guarantees. Certain of the Company’s leases include renewal options and escalation clauses; renewal options have not been included in the calculation of the lease liabilities and right-of-use assets as the Company is not reasonably certain to exercise the options. Annual rent increases are included in the calculation of the operating lease right-of-use assets. Variable expenses generally represent the Company’s share of the landlord’s operating expenses and are recorded when incurred. Incremental borrowing rates used to discount future lease payments in calculating lease liabilities were estimated by reference to the rate on the Company’s MidCap Term Loan. The Company does not have any operating lease arrangements where it acts as a lessor.

	Three Months Ended		Six Months Ended
	June 30, 2019		June 30, 2019
Operating leases
Operating lease cost	$	164,550	$	260,731
Variable lease cost		31,807		53,258
Operating lease expense		196,357		313,989
Short-term lease rent expense		—		1,497
Total rent expense	$	196,357	$	315,486

The table below summarizes other information related to the Company’s operating leases:


	Six Months Ended or As of June 30, 2019
Operating cash flows from operating leases	$	338,089
Establishment of operating lease liabilities arising from obtaining right-of-use assets	$	1,927,652
Weighted-average remaining lease term – operating leases		2.7
Weighted-average discount rate – operating leases		9.6	%

As of June 30, 2019, remaining maturities of our operating leases, excluding short-term leases, are as follows:

Six months ended December 31, 2019	$	402,451
2020		809,597
2021		327,421
2022		281,232
2023		70,847
Total		1,891,548
Less present value discount		(231,899	)
Operating lease liabilities, net	$	1,659,649

Prior to the Company’s adoption of ASC 842, rent expense was $143,158 and $291,255 for the three and six months ended June 30, 2018, respectively, recorded on a straight-line basis. Lease commitments as presented under ASC 840 as of December 31, 2018 were as follows:

2019	$	525,745
2020		528,225
2021		53,907
2022		10,768
2023		10,768
2024 and beyond		43,073
		1,172,486

Financing Leases

The Company has a number of computer equipment leases that are classified as financing leases. Incremental borrowing rates used to discount future lease payments in calculating lease liabilities were estimated by reference to information received by the Company from bankers regarding estimated current borrowing rates for collateralized loans with similar amount and duration as the leases. The Company does not have any material financing leases where it acts as a lessor. The components of lease cost for financing leases were as follows:

	Three Months Ended		Six Months Ended
	June 30, 2019		June 30, 2019
Financing leases
Amortization of right-of-use assets	$	12,084	$	26,780
Interest on lease liability		1,823		3,969
Total financing lease cost	$	13,907	$	30,749

The table below summarizes other information related to the Company’s financing leases:

	June 30,
	2019
Weighted-average remaining lease term – financing leases		2.2
Weighted-average discount rate – financing leases		9.77	%

As of June 30, 2019, remaining maturities of our financing leases are as follows:

2019	$	24,122
2020		33,992
2021		12,275
2022		4,636
2023		2,316
Total		77,341
Less present value discount		(10,123	)
Financing lease liabilities, net	$	67,218

At June 30, 2019, the Company had financing lease liabilities net of discount of $67,218, of which $36,616 was included in other current liabilities and $30,602 was included in other non-current liabilities, and financing right-of-use assets of $65,966, which were included in property and equipment, net, in the accompanying condensed consolidated balance sheet.