Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net loss	$ (22,105)	$ (24,656)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	283	62
Stock-based compensation expense	1,658	1,608
Equity in net loss of equity method investment	40
Change in fair value of preferred stock warrants	(1,632)	5,152
Changes in assets and liabilities:
Accounts receivable	(1,660)	67
Prepaid expenses and other current assets	(2,207)	(37)
Other assets	(648)	(304)
Deferred revenue	(97)	120
Accounts payable, accrued liabilities and other	2,097	431
Net cash used in operating activities	(24,271)	(17,557)
Cash flows from investing activities
Purchase of equity method investment	(1,000)
Purchase of property and equipment	(677)	(698)
Net cash used in investing activities	(1,677)	(698)
Cash flows from financing activities
Proceeds from issuance of preferred stock, net		21,060
Proceeds from issuance of common stock, net	25,079
Proceeds from stock option exercises	10
Net cash provided by financing activities	25,089	21,060
Net increase (decrease) in cash and cash equivalents	(859)	2,805
Cash and cash equivalents at
Cash and cash equivalents at beginning of period	25,096	22,291
Cash and cash equivalents at end of period	24,237	25,096
Supplemental cash flow information
Cash paid for taxes	2	1
Non-cash investing and financing activities
Preferred stock dividends issued	1,357	2,793
Reclassification of warrant liability to equity	10,236
Issuance of common stock warrants attributed to private offerings		$ 352
Property and equipment additions	$ 120