BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 16,335	$ 12,810
Restricted cash	268	268
Marketable securities	78,351	102,035
Interest and other receivables	436	475
Prepaid assets	580	524
Total current assets	95,970	116,112
Noncurrent marketable securities	14,241	13,954
Property and equipment, net	102	183
Total assets	110,313	130,249
Current liabilities:
Accounts payable	503	225
Accrued compensation and benefits	3,385	2,843
Accrued collaboration charges	1,702	3,367
Accrued liabilities	926	1,434
Total current liabilities	6,516	7,869
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 3,000,000 shares authorized; no shares issued and outstanding at December 31, 2017 and 2016
Common stock, $0.001 par value; 300,000,000 shares authorized; 159,877,239 and 159,158,636 shares issued and outstanding at December 31, 2017 and 2016, respectively	160	159
Additional paid-in capital	1,089,684	1,080,198
Accumulated deficit	(985,840)	(957,924)
Accumulated other comprehensive loss	(207)	(53)
Total stockholders' equity	103,797	122,380
Total liabilities and stockholders' equity	$ 110,313	$ 130,249

Carrying value as of the balance sheet date of obligations incurred and payable to collaboration partner for which invoices have not yet been received under the respective collaboration agreement (due within one year or within the normal operating cycle if longer).

No definition available.