Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 36,720	$ 39,814
Due from Novartis Pharma, AG	247	960
Available for sale securities	412,320	423,746
Prepaid expenses and other current assets	10,885	8,812
Deferred tax assets	106	50
Total current assets	460,278	473,382
Property and equipment, net	1,809	1,555
Deferred tax assets, non-current	8,443	4,467
Security deposits	467	282
Other Assets	52	100
Total assets	471,049	479,786
Current liabilities
Accounts payable and accrued expenses	6,150	8,707
Accrued research and development expenses	9,775	7,918
Deferred revenue	6,755	3,206
Total current liabilities	22,680	19,831
Deferred revenue, long-term	209,593	206,418
Royalty purchase liability	125,000	125,000
Total liabilities	$ 357,273	$ 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, 34,675,404 and 33,994,520 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	$ 35	$ 34
Additional paid-in capital	444,034	428,390
Accumulated deficit	(330,317)	(299,822)
Accumulated other comprehensive income (loss)	24	(65)
Total stockholders' equity	113,776	128,537
Total liabilities and stockholders' equity	$ 471,049	$ 479,786