Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 77,132	$ 64,418
Marketable securities	121,179	159,455
Accounts receivable, net of allowance for credit losses of $43 and $43, respectively	453	441
Other receivables	3,186	9,558
Prepaid expenses and other current assets	10,876	10,148
Total current assets	212,826	244,020
Property and equipment, net	18,456	11,607
Facility and equipment under lease	2,662	3,806
Other assets	3,994	4,000
Total assets	237,938	263,433
Current liabilities:
Accounts payable and other accrued liabilities	52,985	54,284
Accrued payroll and benefits	8,113	7,686
Total current liabilities	61,098	61,970
Other long-term liabilities	8,480	11,070
Total liabilities	69,578	73,040
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 300,000,000 shares authorized; 145,931,172 and 113,299,612 issued and outstanding at September 30, 2020 and December 31, 2019, respectively	146	113
Additional paid-in capital	1,016,474	918,205
Accumulated other comprehensive loss	(2,724)	(3,498)
Accumulated deficit	(845,536)	(724,427)
Total stockholders’ equity	168,360	190,393
Total liabilities and stockholders’ equity	$ 237,938	$ 263,433