STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (23,846)	$ (10,247)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	105	96
Stock-based compensation	332	77
Non-cash interest expense	3,664	2,711
Change in fair value warrant liability	(11)	(1,019)
Change in fair value derivative liability	676	57
Changes in operating assets and liabilities:
Other receivable	(233)
Prepaid expenses and other assets	(1,017)	40
Accounts payable	1,337	(213)
Accrued expenses	1,923	242
Deferred rent	17	(3)
Net cash used in operating activities	(17,053)	(8,259)
Investing activities
Purchases of property and equipment	(119)	(216)
Net cash used in investing activities	(119)	(216)
Financing activities
Proceeds from issuance of common stock in initial public offering, net	42,974
Proceeds from issuance of redeemable convertible preferred stock, net	17,712
Proceeds from term loan, net	3,995	3,480
Proceeds from exercise of stock options	92	3
Proceeds from exercise of warrants	24
Proceeds from convertible promissory notes, net		14,683
Net cash provided by financing activities	64,797	18,166
Net increase in cash and cash equivalents	47,625	9,691
Cash, cash equivalents and restricted cash at the beginning of the year	13,426	3,735
Cash, cash equivalents and restricted cash at the end of the year	61,051	13,426
Supplemental disclosure for cash flow
Cash paid for interest	260	12
Supplemental disclosure of cash flow information
Conversion of redeemable convertible preferred stock into common stock	125,609
Conversion of convertible promissory notes into redeemable convertible preferred stock	19,778
Warrant liability converted to redeemable convertible preferred stock upon the exercise of warrants	4,297
Issuance of warrants in conjunction with debt	2,822	1,795
Conversion of redeemable convertible preferred stock warrants into common stock warrants	3,346
Accretion of redeemable convertible preferred stock	95	67
Purchases of property and equipment included in accounts payable	$ 39
Issuance of derivative in conjunction with debt		$ 2,971