Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 67,776	$ 81,146
Prepaid expenses and other current assets	686	562
Total current assets	68,462	81,708
Restricted cash	2,388	2,383
Property and equipment, net	680	798
Build-to-suit lease asset	8,770	8,888
Total assets	80,300	93,777
Current liabilities
Accounts payable	804	1,500
Accrued liabilities	3,234	4,093
Total current liabilities	4,038	5,593
Build-to-suit lease obligation	7,324	5,428
Total liabilities	11,362	11,021
Commitments and contingencies (Note 5)
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized at June 30, 2018 and December 31, 2017; 36,240,673 and 35,938,126 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	4	4
Additional paid-in capital	461,995	456,984
Accumulated deficit	(393,061)	(374,232)
Total stockholders' equity	68,938	82,756
Total liabilities and stockholders’ equity	$ 80,300	$ 93,777

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).