Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 14,252	$ 9,140
Marketable securities at fair value	3,488	13,862
Prepaid expenses and other current assets	991	358
Total current assets	18,731	23,360
Restricted cash	455	455
Property and equipment, net	20,568	11,916
Operating lease right-of-use assets	6,016
Other long-term assets	17	49
Total assets	45,787	35,780
Current liabilities:
Accounts payable	5,985	4,450
Accrued compensation	1,459	2,092
Build-to-suit obligation, current portion	3,147	2,326
Operating lease liabilities, current portion	1,026
Other accrued liabilities	3,678	2,419
Total current liabilities	15,295	11,287
Build-to-suit obligation, long-term portion, net of debt issuance costs and discount	5,091	4,478
Operating lease liabilities, long-term portion	6,369
Other liabilities	25	18
Deferred rent	0	1,287
Total liabilities	26,780	17,070
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding as of June 30, 2019 and December 31, 2018	0	0
Common stock, $0.0001 par value; 250,000,000 shares authorized; 17,723,039 and 11,973,039 shares issued and outstanding as of June 30, 2019 and December 31, 2018, respectively	2	1
Additional paid-in capital	299,023	279,946
Accumulated deficit	(280,018)	(261,232)
Accumulated other comprehensive loss	0	(5)
Total stockholders’ equity	19,007	18,710
Total liabilities and stockholders’ equity	$ 45,787	$ 35,780