UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 24,577	$ 48,460
Short-term investments	74,223	62,326
Accounts receivable	27	16
Unbilled revenue receivable	11	19
Prepaid expenses and other assets	2,906	1,955
Total current assets	101,744	112,776
Property and equipment, net	2,298	2,099
Other noncurrent assets	1,487	388
Total assets	105,529	115,263
Current liabilities:
Current portion of long-term debt	0	4,965
Accounts payable	3,392	1,814
Accrued expenses and other current liabilities	1,268	2,435
Current portion of deferred revenue		21,873
Total current liabilities	20,373	31,087
Common stock warrant liability	42	414
Deferred revenue non-current	0	2,956
Other noncurrent liabilities	0	59
Total liabilities	20,415	34,516
Stockholders’ equity:
Common stock, $0.0001 par value per share; 200,000,000 shares authorized, 87,150,447 issued and outstanding, March 31, 2020; 86,069,263 issued and outstanding, December 31, 2019	9	9
Additional paid-in capital	165,269	162,062
Accumulated other comprehensive loss	(17)	(27)
Accumulated deficit	(80,147)	(81,297)
Total stockholders' equity	85,114	80,747
Total liabilities and stockholders’ equity	$ 105,529	$ 115,263