Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 6,181	$ 19,371
Restricted cash	50
Available-for-sale investments		2,496
Prepaid expenses and other current assets	744	1,369
Total current assets	6,975	23,236
Property and equipment, net		263
Restricted cash		22
Total assets	6,975	23,521
Current liabilities:
Accounts payable	263	441
Accrued expenses	320	2,637
Total current liabilities	583	3,078
Total liabilities	583	3,078
Commitments and contingencies (Note 6)
Common stock, $0.001 par value, 100,000,000 shares authorized at December 31, 2019 and 2018; 557,631 and 481,091 shares issued and outstanding at December 31, 2019 and 2018, respectively
Additional paid-in capital	213,388	209,385
Accumulated deficit	(225,462)	(210,470)
Accumulated other comprehensive income	3	5
Total stockholders’ equity	6,392	20,443
Total liabilities and stockholders’ equity	6,975	23,521
Series A Convertible Preferred Stock [Member]
Current liabilities:
Preferred stock, $0.001 par value per share; 10,000,000 shares authorized at December 31, 2019 and 2018:Series A convertible preferred stock 22,000 shares authorized at December 31, 2019 and December 31, 2018; 18,954 and 22,000 issued and outstanding at December 31, 2019 and at December 31, 2018, respectively	$ 18,463	$ 21,523