UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 17,198	$ 48,460
Short-term investments	68,579	62,326
Accounts receivable	21	16
Unbilled revenue receivable	3	19
Prepaid expenses and other assets	3,588	1,955
Total current assets	89,389	112,776
Property and equipment, net	4,464	2,099
Other noncurrent assets	2,266	388
Total assets	96,119	115,263
Current liabilities:
Current portion of long-term debt	0	4,965
Accounts payable	1,540	1,814
Accrued expenses and other current liabilities	1,947	2,435
Current portion of deferred revenue		21,873
Total current liabilities	14,367	31,087
Common stock warrant liability	0	414
Deferred revenue, noncurrent	0	2,956
Other noncurrent liabilities	0	59
Total liabilities	14,367	34,516
Stockholders’ equity:
Common stock, $0.0001 par value per share; 200,000,000 shares authorized, 87,206,346 issued and outstanding, June 30, 2020; 86,069,263 issued and outstanding, December 31, 2019	9	9
Additional paid-in capital	165,863	162,062
Accumulated other comprehensive income (loss)	338	(27)
Accumulated deficit	(84,458)	(81,297)
Total stockholders' equity	81,752	80,747
Total liabilities and stockholders’ equity	$ 96,119	$ 115,263