Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 254,895	$ 39,814
Available for sale securities	26,147	423,746
Due from Novartis Pharma AG		960
Prepaid expenses and other current assets	5,541	8,812
Deferred tax assets	1,500	50
Total current assets	288,083	473,382
Available for sale securities	144,944
Property and equipment, net	2,590	1,555
Deferred tax assets, non-current	14,632	4,467
Security deposits	467	282
Other Assets	35	100
Total assets	450,751	479,786
Current liabilities
Accrued research and development expenses	20,080	7,918
Accounts payable and accrued expenses	7,850	8,707
Deferred revenue	6,714	3,206
Total current liabilities	34,644	19,831
Deferred revenue, long-term	207,996	206,418
Royalty purchase liability	125,000	125,000
Total liabilities	$ 367,640	$ 351,249
Stockholders' equity
Preferred stock - $0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding
Common stock - $0.001 par value, 200,000,000 shares authorized, 34,903,881 and 33,994,520 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	$ 35	$ 34
Additional paid-in capital	452,887	428,390
Accumulated deficit	(369,890)	(299,822)
Accumulated other comprehensive income (loss)	79	(65)
Total stockholders' equity	83,111	128,537
Total liabilities and stockholders' equity	$ 450,751	$ 479,786