Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Significant Components of Deferred Tax Assets

Significant components of our deferred tax assets are as follows:

	December 31,
	2013		2012
Deferred tax assets:		(in thousands)
Federal and state net operating losses	$	55,955	$	45,954
Capitalized research and patent costs		23,395		22,442
Research credits		21,252		19,236
Biopharma Financing Agreement		13,021		12,108
Stock-based compensation costs		5,398		4,320
Other		1,148		189
Total deferred tax assets		120,169		104,249
Valuation allowance		(120,169)		(104,249)
Net deferred tax assets	$	—	$	—

Reconciliation of Statutory Federal Income Tax Rate to Effective Rate

The following table presents a reconciliation from the statutory federal income tax rate to the effective rate.

	Year ended December 31,
	2013			2012			2011
	(in thousands)
U.S. federal taxes (benefit) at statutory rate	$	(15,644	)	$	(12,936	)	$	(11,000	)
Unutilized, net operating loss		14,666			11,663			8,588
Non-deductible offset of Orphan Drug Credit		383			827			2,119
Non-deductible stock based compensation		567			404			280
Other		28			42			13
Total	$	—		$	—		$	—