Condensed Balance Sheets (USD $)	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 32,586,000	$ 79,311,000
Restricted cash, current portion	11,133,000	7,657,000
Marketable securities	31,956,000
Prepaid expenses and other current assets	521,000	621,000
Total current assets	76,196,000	87,589,000
Property and equipment, net	150,000	275,000
Restricted cash-net of current portion		8,321,000
Other assets	37,000	37,000
Total assets	76,383,000	96,222,000
Current liabilities:
Accounts payable	1,745,000	2,152,000
Accrued personnel costs	1,652,000	2,173,000
Accrued costs for services	4,288,000	4,862,000
Accrued interest	120,000	22,000
Note payable, current portion	4,836,000	1,160,000
Deferred development funds, current portion	9,063,000	5,853,000
Total current liabilities	21,704,000	16,222,000
Deferred rent	11,000	9,000
Deferred development funds-net of current portion		8,321,000
Note payable-net of current portion	8,804,000	2,764,000
Total liabilities	30,519,000	27,316,000
Commitments and contingencies
Stockholders' equity:
Common stock, $0.00001 par value, 300,000,000 shares authorized, 18,625,000 and 18,325,000 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively
Additional paid in capital	192,585,000	189,212,000
Accumulated other comprehensive loss	(31,000)
Accumulated deficit	(146,690,000)	(120,306,000)
Total stockholders' equity	45,864,000	68,906,000
Total liabilities and stockholders' equity	$ 76,383,000	$ 96,222,000