Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 40,117	$ 73,849
Accounts receivable	378	201
Prepaid expenses and other current assets	1,104	1,076
Inventories	1,057	115
Restricted cash		80
Total current assets	42,656	75,321
Property and equipment, net	9,448	2,760
Restricted cash, net of current portion	260	260
Deferred tax assets	313	313
Other assets	447	480
Total assets	53,124	79,134
Current liabilities:
Accounts payable	993	735
Accrued expenses and other current liabilities	4,291	3,662
Notes payable	1,417	295
Deferred revenue	1,199	80
Deferred tax liabilities	313	313
Lease incentives	241	87
Total current liabilities	8,454	5,172
Notes payable, net of current portion	19,344	20,660
Lease incentives, net of current portion	1,136	106
Other liabilities	$ 380	$ 195
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued
Common stock, $0.001 par value; 200,000,000 shares authorized; 20,339,261 and 20,041,645 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	$ 20	$ 20
Additional paid-in capital	160,643	156,576
Accumulated deficit	(136,853)	(103,595)
Total stockholders' equity	23,810	53,001
Total liabilities and stockholders' equity	$ 53,124	$ 79,134