Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning balance (in shares) at Dec. 31, 2018	3,081,546
Beginning balance at Dec. 31, 2018	$ 3	$ 97	$ (4,806)	$ (4,706)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 0	459	0	459
Issuance of common stock and warrants in a private offering, net of $16.5 million warrant liability, shares	1,829,407
Issuance of common stock and warrants in a private offering, net of $16.5 million warrant liability	$ 2	0	0	2
Effect of reverse merger, shares	947,218
Effect of reverse merger	$ (1)	(300)	0	(299)
Issuance of common stock for license acquired, shares	992,782
Issuance of common stock for license acquired	$ 1	2,999	0	3,000
Warrants exercised for cash (in shares)	14,332,620
Warrants exercised for cash	$ 14	4,503	0	4,517
Reclass of warrant liabilites related to Series A warrants exercised for cash, shares	0
Reclass of warrant liabilites related to Series A warrants exercised for cash	$ 0	5,600	0	5,600
Reclass of Series B warrants from warrant liability to stockholders' equity, shares	0
Reclass of Series B warrants from warrant liability to stockholders' equity	$ 0	31,473	0	31,473
Issuance of common stock for conversion of debt and accrued interest, shares	172,284
Issuance of common stock for conversion of debt and accrued interest	$ 0	2,715	9	2,715
Issuance of common stock and warrants, pursuant to Securities Purchase Agreement, net of issuance costs, shares	4,475,000
Issuance of common stock and warrants, pursuant to Securities Purchase Agreement, net of issuance costs	$ 5	5,915	0	5,920
Issuance of common stock in at-the-market offering, net of issuance costs, shares	1,197,676
Issuance of common stock in at-the-market offering, net of issuance costs	$ 1	2,566	0	2,567
Net loss	$ 0	0	(51,255)	(51,255)
Ending balance (in shares) at Dec. 31, 2019	27,028,533
Ending balance at Dec. 31, 2019	$ 27	56,027	(56,061)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 0	2,044	0	2,044
Issuance of common stock for prepaid services, shares	400,000
Issuance of common stock for prepaid services	$ 0	330	0	330
Issuance of common stock for license acquired, shares	1,809,845
Issuance of common stock for license acquired	$ 2	2,441	0	0
Issuance of common stock, net of issuance costs, shares	15,166,666
Issuance of common stock, net of issuance costs	$ 15	8,835	0	8,850
Warrants exercised for cash (in shares)	153,628
Warrants exercised for cash	$ 0	169	0	169
Reclass of Series B warrants from warrant liability to stockholders' equity				0
Issuance of common stock and warrants, pursuant to Securities Purchase Agreement, net of issuance costs, shares	1,112,219
Issuance of common stock and warrants, pursuant to Securities Purchase Agreement, net of issuance costs	$ 1	1,378	0	1,379
Beneficial conversion feature of convertible debt, shares	0
Beneficial conversion feature of convertible debt	$ 0	100	0	100
Issuance of common stock and warrants, pursuant to September 2020 Securities Purchase Agreement, net of issuance costs, shares	8,865,000
Issuance of common stock and warrants, pursuant to September 2020 Securities Purchase Agreement, net of issuance costs	$ 9	6,356	0	6,365
Net loss	$ 0	0	(19,101)	(19,101)
Ending balance (in shares) at Dec. 31, 2020	54,535,891
Ending balance at Dec. 31, 2020	$ 54	$ 77,680	$ (75,162)	$ 2,572