Condensed Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 29,335	$ 66,373
Available for sale securities	150,866	143,674
Prepaid expenses and other current assets	5,310	4,791
Income tax receivable	1,765	1,765
Total current assets	187,276	216,603
Property and equipment, net	17	26
Right-of-use asset, net	107	120
Other assets	2	5
Total assets	187,402	216,754
Current liabilities
Accrued research and development expenses	13,132	12,284
Accounts payable and accrued expenses	6,976	12,792
Lease liability	55	54
Total current liabilities	20,163	25,130
Lease liability, non-current	51	61
Total liabilities	20,214	25,191
Stockholders' equity
Preferred stock—$0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock—$0.001 par value, 200,000,000 shares authorized, 90,169,616 and 90,120,797 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	90	90
Additional paid-in capital	758,964	756,543
Accumulated deficit	(591,868)	(565,073)
Accumulated other comprehensive income	2	3
Total stockholders' equity	167,188	191,563
Total liabilities and stockholders' equity	$ 187,402	$ 216,754