Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents (Note 5)	$ 130,550	$ 150,180
Prepaid expenses and other current assets (Note 5)	543	1,673
Total current assets	131,093	151,853
Property and equipment, net (Note 5)	401	566
Other assets	200	349
TOTAL ASSETS	131,694	152,768
CURRENT LIABILITIES:
Accrued liabilities (Note 5)	6,190	7,016
Accounts payable	734	358
Other current liabilities		23
Total current liabilities	6,924	7,397
TOTAL LIABILITIES	6,924	7,397
Commitments and Contingencies (Note 6)
STOCKHOLDERS' EQUITY (DEFICIT):
Preferred stock, $0.001 par value; 10,000,000 shares authorized as of June 30, 2016 and December 31, 2015; nil shares issued and outstanding as of June 30, 2016 and December 31, 2015
Common stock, $0.001 par value; 500,000,000 shares authorized as of June 30, 2016 and December 31, 2015; 30,220,083 and 30,058,105 shares issued and outstanding as of June 30, 2016 and December 31, 2015	30	30
Additional paid-in capital	682,337	679,528
Accumulated deficit	(557,597)	(534,187)
TOTAL STOCKHOLDERS' EQUITY	124,770	145,371
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 131,694	$ 152,768

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).