Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 4,619	$ 2,925
Prepaid expenses and other current assets	117	113
Deferred offering costs	2,330
Total current assets	7,066	3,038
Furniture, fixtures and equipment, net	114	133
Other assets, net	62	48
Total assets	7,242	3,219
Current liabilities
Accounts payable and other current liabilities	3,175	1,437
Notes payable, net of discount-related parties	14,433	2,331
Interest payable-related parties	504	16
Total current liabilities	18,112	3,784
Warrants liability-related parties	11,485	2,456
Total liabilities	29,597	6,240
Commitments and contingencies (Note 9)
Convertible preferred stock
Convertible preferred stock	61,311	60,898
Stockholders' deficit
Common stock, $0.001 par value; 22,000,000 shares authorized as of September 30, 2013 and 20,000,000 shares authorized as of December 31, 2012; 1,021,209 and 964,880 shares issued and outstanding at September 30, 2013 (unaudited) and December 31, 2012, respectively	1	1
Additional paid-in capital	1,123	4
Deficit accumulated during the development stage	(84,790)	(63,924)
Total stockholders' deficit	(83,666)	(63,919)
Total liabilities, convertible preferred stock and stockholders' deficit	7,242	3,219
Convertible Preferred Stock Series A-1 [Member]
Convertible preferred stock
Convertible preferred stock	1,000	1,000
Convertible Preferred Stock Series A-2 [Member]
Convertible preferred stock
Convertible preferred stock	10,000	10,000
Convertible Preferred Stock Series A-3 [Member]
Convertible preferred stock
Convertible preferred stock	20,979	20,979
Convertible Preferred Stock Series A-4 [Member]
Convertible preferred stock
Convertible preferred stock	4,826	4,606
Convertible Preferred Stock Series B [Member]
Convertible preferred stock
Convertible preferred stock	$ 24,506	$ 24,313