Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 209,771	$ 234,854
Accounts receivable, net	2,049	0
Grants and other receivables	271	46
Inventory	3,580	2,013
Prepaid expenses and other current assets	1,398	1,254
Total current assets	217,069	238,167
Property and equipment, net	3,102	2,564
Other assets	391	405
Total assets	220,562	241,136
Current liabilities:
Accounts payable	7,996	5,893
Accrued expenses	14,492	8,698
Deferred other income	0	186
Total current liabilities	22,488	14,777
Long-term debt, net	71,963	71,863
Total liabilities	94,451	86,640
Stockholders' equity:
Common stock, $0.001 par value; 200,000,000 shares authorized at March 31, 2018 and December 31, 2017; 37,909,058 and 37,802,556 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	38	38
Additional paid-in capital	368,018	365,838
Accumulated deficit	(241,841)	(211,269)
Accumulated other comprehensive loss	(104)	(111)
Total stockholders' equity	126,111	154,496
Total liabilities and stockholders' equity	$ 220,562	$ 241,136

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.