CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (13,015)	$ (5,566)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	25	37
Accretion of discount on marketable securities	(25)	0
Non-cash interest expense	666	0
Change in fair value of derivative liability	11	0
Change in fair value of warrant liability	(223)	(8)
Gain on extinguishment	(2,318)	0
Amortization of operating lease right-of-use assets	50	50
Amortization of convertible promissory notes discount	828	0
Amortization of debt discounts and financing costs	215	310
Stock-based compensation	1,007	516
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,480)	14
Accounts payable	(2,776)	473
Accrued liabilities	(2,207)	(343)
Lease liability	(50)
Research and development funding liability	5,600	0
Deferred revenue	(7,248)	12,188
Net cash provided by (used in) operating activities	(21,940)	7,621
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash and cash equivalents acquired in recapitalization	13,017	0
Maturities of marketable securities	5,500	0
Capital expenditures	(8)	(8)
Net cash provided by (used in) investing activities	18,509	(8)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments of principal of note payable	(4,808)	(509)
Proceeds from issuance of convertible promissory notes	7,397	0
Proceeds from the exercise of stock options	0	27
Net cash provided by (used in) financing activities	2,589	(482)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(842)	7,131
CASH AND CASH EQUIVALENTS—BEGINNING	8,067	5,399
CASH AND CASH EQUIVALENTS—ENDING	7,225	12,530
Supplement Disclosure of Cash Flow Information:
Interest paid	319	310
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Conversion of redeemable convertible preferred stock and preferred stock dividends to common stock	48,016	0
Accretion (reduction) of redeemable convertible preferred stock to redemption value	(10,377)	5,041
Shares issued in recapitalization	23,076	0
Accretion of redeemable convertible preferred stock issuance costs	103	30
Derivative liability issued with convertible promissory notes	1,442	0
Warrants to purchase common stock issued with funding agreement	876	0
Warrants to purchase common stock issued with convertible promissory notes	1,492	0
Change in unrealized loss on available-for-sale marketable securities	$ (11)	$ 0