CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 129,558	$ 153,225
Accounts receivable	3,349	2,129
Inventory	1,495	1,316
Prepaid expenses and other current assets	2,064	1,905
Total current assets	136,466	158,575
Property and equipment, net	1,007	1,038
Intangible assets, net	1,973	2,103
Restricted cash	97	97
Other long-term assets	305	204
Total assets	139,848	162,017
Current liabilities:
Accounts payable	6,793	9,106
Accrued expenses	6,488	8,879
Deferred revenue	8,695	4,944
Current portion of term loan payable	2,556	2,667
Total current liabilities	24,532	25,596
Lease incentive obligation	25	34
Term loan payable, long-term	924	1,479
Total liabilities	25,481	27,109
Commitments and contingencies (see Note 10)
Shareholders’ equity (deficit):
Preferred stock, $0.001 par value; authorized shares - 5,000,000 at March 31, 2017 and December 31, 2016; issued and outstanding shares - none at March 31, 2017 and December 31, 2016
Common stock, $0.001 par value; authorized shares - 100,000,000 at March 31, 2017 and December 31, 2016; issued and outstanding shares - 29,458,557 at March 31, 2017 and 29,364,100 at December 31, 2016	29	29
Additional paid-in capital	360,600	358,063
Accumulated deficit	(246,262)	(223,184)
Total shareholders’ equity	114,367	134,908
Total liabilities and shareholders’ equity	$ 139,848	$ 162,017