Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 131,201	$ 166,972
Prepaid expenses and other current assets	2,086	3,146
Income tax receivable	0	1,387
Total current assets	133,287	171,505
Property and equipment, net	335	518
Income tax receivable, non-current	3,529	0
Deferred tax assets	0	3,529
Other assets	14	24
Total assets	137,165	175,576
Current liabilities
Accrued research and development expenses	7,337	4,984
Accounts payable and accrued expenses	5,869	7,551
Total current liabilities	13,206	12,535
Royalty purchase liability	0	125,000
Total liabilities	13,206	137,535
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, 41,397,197 and 36,110,298 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	41	36
Additional paid-in capital	545,585	522,759
Accumulated deficit	(421,667)	(484,754)
Total stockholders' equity	123,959	38,041
Total liabilities and stockholders' equity	$ 137,165	$ 175,576