CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 15,159	$ 17,504
Prepaid expenses and other current assets	2,991	2,283
Total current assets	18,150	19,787
Property and equipment, net	29	36
Right-of-use lease asset	1,285
Total assets	19,464	19,823
Current liabilities:
Accounts payable	1,106	2,719
Accrued and other current liabilities	1,394	1,732
Total current liabilities	2,500	4,451
Lease liability	1,233
Other liabilities		100
Total liabilities	3,733	4,551
Stockholders' equity:
Preferred stock, value
Common stock, $0.001 par value; 100,000,000 shares authorized at December 31, 2018 and June 30, 2019; 12,497,447 and 17,199,974 shares issued and outstanding at December 31, 2018 and June 30, 2019.	(17)	(12)
Additional paid-in capital	369,944	365,817
Accumulated other comprehensive loss	(808)	(760)
Accumulated deficit	(353,422)	(349,797)
Total stockholders' equity	15,731	15,272
Total liabilities and stockholders' equity	19,464	19,823
Convertible Exchangeable Preferred Stock
Stockholders' equity:
Preferred stock, value
Series A convertible preferred stock
Stockholders' equity:
Preferred stock, value

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).