Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 106,889	$ 131,201
Prepaid expenses and other current assets	1,937	2,086
Income tax receivable	1,765	0
Total current assets	110,591	133,287
Property and equipment, net	252	335
Right-of-use asset, net	989
Income tax receivable, non-current	1,765	3,529
Other assets	11	14
Total assets	113,608	137,165
Current liabilities
Accrued research and development expenses	7,645	7,337
Accounts payable and accrued expenses	3,241	5,869
Lease liability	989
Total current liabilities	11,875	13,206
Total liabilities	11,875	13,206
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, 41,477,420 and 41,397,197 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	41	41
Additional paid-in capital	550,303	545,585
Accumulated deficit	(448,611)	(421,667)
Total stockholders' equity	101,733	123,959
Total liabilities and stockholders' equity	$ 113,608	$ 137,165