CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (12,280)	$ (13,174)
Adjustments to reconcile net loss to cash flows used in operating activities:
Amortization of intangible assets	615	615
Depreciation of property and equipment	72	33
Amortization of debt discount	147	171
Non-cash interest expense	0	323
Stock-based compensation	988	1,160
Changes in operating assets and liabilities:
Accounts receivable and other current assets	(2,317)	(2,320)
Inventory	(248)	(1,221)
Accounts payable and accrued expenses	(1,798)	(1,944)
Right-of-use assets and operating lease liabilities	(38)	(3)
Deferred revenue	(240)	15
Net cash used in operating activities	(15,099)	(16,345)
Cash flows from investing activities:
Purchases of property and equipment	0	(16)
Net cash used in investing activities	0	(16)
Cash flows from financing activities:
Proceeds from issuance of stock, net of issuance costs	108,732	20,285
Net settlement of stock units to satisfy statutory tax withholding	(128)	(19)
Proceeds from exercise of stock options	183	187
Principal payments on finance lease obligations	(18)	(7)
Net cash provided by financing activities	108,769	20,446
Net increase (decrease) in cash, cash equivalents and restricted cash	93,670	4,085
Cash, cash equivalents and restricted cash at beginning of year	45,059	22,364
Cash, cash equivalents and restricted cash at end of year	138,729	26,449
Supplemental cash flow information:
Cash interest paid	1,195	1,290
Supplemental disclosure of non-cash investing and financing activities:
Stock issuance costs	329	295
Principal portion of finance lease liabilities	$ 12	$ 7