Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 221,491	$ 234,854
Accounts receivable, net	2,923	0
Grants and other receivables	182	46
Inventory	7,009	2,013
Prepaid expenses and other current assets	1,850	1,254
Total current assets	233,455	238,167
Property and equipment, net	3,957	2,564
Other assets	210	405
Total assets	237,622	241,136
Current liabilities:
Accounts payable	6,549	5,893
Accrued expenses	15,645	8,698
Deferred other income	168	186
Total current liabilities	22,362	14,777
Long-term debt, net	72,318	71,863
Other liabilities	212	0
Total liabilities	94,892	86,640
Stockholders' equity:
Common stock, $0.001 par value; 200,000,000 shares authorized at September 30, 2018 and December 31, 2017; 41,227,530 and 37,802,556 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	41	38
Additional paid-in capital	434,312	365,838
Accumulated deficit	(291,546)	(211,269)
Accumulated other comprehensive loss	(77)	(111)
Total stockholders' equity	142,730	154,496
Total liabilities and stockholders' equity	$ 237,622	$ 241,136