Note 5. Balance Sheet Components

Cash Equivalents and Marketable Securities

Cash equivalents and marketable securities consisted of the following (in thousands):


	December 31, 2019
	Amortized		Gross Unrealized
	Cost		Gains		Losses		Fair Value
Money market funds	$	12,964	$	—	$	—	$	12,964
Commercial paper		44,284		2		(4)		44,282
Corporate debt securities		33,653		11		(2)		33,662
U.S. Treasury and agency securities		40,798		14		(2)		40,810
Total cash equivalents and marketable securities	$	131,699	$	27	$	(8)	$	131,718
Classified as:
Cash equivalents							$	31,707
Marketable securities								100,011
Total cash equivalents and marketable securities							$	131,718


	December 31, 2018
	Amortized		Gross Unrealized
	Cost		Gains		Losses		Fair Value
Money market funds	$	25,390	$	—	$	—	$	25,390
Commercial paper		59,730		—		—		59,730
Corporate debt securities		8,997		—		(8)		8,989
U.S. Treasury and agency securities		33,423		—		(29)		33,394
Total cash equivalents and marketable securities	$	127,540	$	—	$	(37)	$	127,503
Classified as:
Cash equivalents							$	80,883
Marketable securities								46,620
Total cash equivalents and marketable securities							$	127,503

All marketable securities held as of December 31, 2019 and 2018 had contractual maturities of less than one year. There were no material realized gains or realized losses from sales of marketable securities for the periods presented.

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	December 31,
	2019		2018
Prepaid clinical and research related expenses	$	2,567	$	686
Prepaid insurance		1,161		438
Other prepaid expenses		1,057		1,005
Other receivable		744		495
Prepaid expenses and other current assets	$	5,529	$	2,624

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2019		2018
Laboratory equipment	$	2,947	$	2,533
Furniture and computer equipment		512		338
Leasehold improvements		863		67
Total property and equipment		4,322		2,938
Less: accumulated depreciation and amortization		(2,641)		(2,077)
Property and equipment, net	$	1,681	$	861

Depreciation expense for the years ended December 31, 2019, 2018, and 2017 was $703,000, $527,000 and $406,000, respectively. As of December 31, 2019, 2018 and 2017, $37,000, $200 and $1,200, respectively, of property and equipment, net, was located in Australia. The remainder of the Company’s property and equipment is located in the United States.

Accrued Expenses and Other Payables

Accrued expenses and other payables consisted of the following (in thousands):


	December 31,
	2019		2018
Accrued clinical and research related expenses	$	7,232	$	7,781
Accrued employee related expenses		4,637		2,726
Accrued professional service fees		301		61
Accrued interest payable		68		—
Other		122		595
Total accrued expenses and other payables	$	12,360	$	11,163