BALANCE SHEETS - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 21,248,000	$ 42,796,000
Restricted cash	267,000	266,000
Marketable securities	92,524,000	108,645,000
Interest and other receivables	1,206,000	963,000
Prepaid assets	647,000	736,000
Total current assets	115,892,000	153,406,000
Noncurrent marketable securities	32,661,000	18,932,000
Property and equipment, net	207,000	173,000
Total assets	148,760,000	172,511,000
Current liabilities:
Accounts payable	160,000	1,033,000
Accrued compensation and benefits	2,974,000	4,213,000
Accrued collaboration charges	2,328,000
Accrued restructuring charges	52,000
Accrued liabilities	1,120,000	1,537,000
Deferred revenue		35,000,000
Fair value of derivatives		16,000
Total current liabilities	$ 6,634,000	$ 41,799,000
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 3,000,000 shares authorized; no shares issued and outstanding at December 31, 2015 and 2014
Common Stock, $0.001 par value; 300,000,000 shares authorized; 158,781,359 and 157,429,871 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 159,000	$ 157,000
Additional paid-in capital	1,070,567,000	1,059,072,000
Accumulated deficit	(928,387,000)	(928,433,000)
Accumulated other comprehensive loss	(213,000)	(84,000)
Total stockholders' equity	142,126,000	130,712,000
Total liabilities and stockholders' equity	$ 148,760,000	$ 172,511,000