Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 38,130	$ 16,901
Short-term investments, available-for-sale	49,635	96,574
Accounts receivable	378	1,233
Prepaid expenses and other current assets	2,100	3,385
Total current assets	90,243	118,093
Property and equipment, net of accumulated depreciation	291	540
Operating lease right-of-use assets	2,943	709
Other long-term assets	27	34
Total assets	93,504	119,376
Current liabilities:
Accounts payable	880	2,398
Accrued liabilities	6,532	6,830
Total current liabilities	7,412	9,228
Lease-related obligations	2,923	196
Total liabilities	10,335	9,424
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized at September 30, 2020 and December 31, 2019; no shares issued and outstanding as of September 30, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value, 200,000,000 shares authorized at September 30, 2020 and December 31, 2019; 62,629,722 and 61,590,013 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	63	62
Additional paid-in capital	783,758	778,693
Accumulated other comprehensive gain, net	33	35
Accumulated deficit	(700,685)	(668,838)
Total stockholders’ equity	83,169	109,952
Total liabilities and stockholders’ equity	$ 93,504	$ 119,376