Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 143,963	$ 200,990
Accounts receivable, net	9,311	2,310
Grants and other receivables	290	242
Inventory	4,260	7,132
Prepaid expenses and other current assets	3,030	2,183
Total current assets	160,854	212,857
Property and equipment, net	3,531	3,884
Other assets	2,187	248
Total assets	166,572	216,989
Current liabilities:
Accounts payable	2,811	7,116
Accrued expenses and other current liabilities	21,556	18,421
Deferred other income	0	160
Total current liabilities	24,367	25,697
Long-term debt, net	72,869	72,500
Other liabilities	864	181
Total liabilities	98,100	98,378
Stockholders' equity:
Common stock, $0.001 par value; 200,000,000 shares authorized at June 30, 2019 and December 31, 2018; 41,430,918 and 41,227,530 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	41	41
Additional paid-in capital	442,676	436,554
Accumulated deficit	(374,178)	(317,927)
Accumulated other comprehensive loss	(67)	(57)
Total stockholders' equity	68,472	118,611
Total liabilities and stockholders' equity	$ 166,572	$ 216,989