Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 125,425	$ 100,348
Prepaid expenses and other current assets	2,423	1,377
Total current assets	127,848	101,725
Property and equipment, net	121	154
Other assets	578	319
TOTAL ASSETS	128,547	102,198
CURRENT LIABILITIES:
Accrued liabilities	6,774	6,133
Accounts payable	1,122	1,339
Total current liabilities	7,896	7,472
TOTAL LIABILITIES	7,896	7,472
Commitments and Contingencies (Note 6)
STOCKHOLDERS' EQUITY:
Preferred stock, $0.001 par value; 10,000,000 shares authorized as of June 30, 2018 and December 31, 2017; nil shares issued and outstanding as of June 30, 2018 and December 31, 2017
Common stock, $0.001 par value; 500,000,000 shares authorized as of June 30, 2018 and December 31, 2017; 74,334,181 and 52,395,223 shares issued and outstanding as of June 30, 2018 and December 31, 2017	74	52
Additional paid-in capital	768,139	718,751
Accumulated deficit	(647,562)	(624,077)
TOTAL STOCKHOLDERS' EQUITY	120,651	94,726
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 128,547	$ 102,198

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).

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- 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).