Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Significant Component of Deferred Tax Assets

Significant components of the Company’s deferred tax assets at December 31, 2013 and 2012 are as follows:

	December 31,
(in thousands)	2013			2012
Net operating loss carryforwards	$	66,209		$	42,715
Start-up and organizational costs		41,529			44,262
Research and development credit carryforwards		25,058			18,388
Stock compensation		1,028			991
Capitalized acquisition costs		12,323			13,270
Deferred revenue		1,074			1,388
Depreciation		129			331
Other		1,254			998
		148,604			122,343
Less valuation allowance		(148,604	)		(122,343	)
Net deferred tax assets	$	—		$	—

Reconciliation of Income Tax Expense (Benefit)

A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows:

	Year Ended December 31,
(in thousands)	2013			2012			2011
Federal income tax at statutory rates		34	%		34	%		34	%
State income tax, net of federal tax benefit		4	%		5	%		6	%
Research and development credits		9	%		10	%		11	%
Stock compensation		-2	%		-1	%		-1	%
Uncertain tax position adjustment		0	%		0	%		0	%
Change in warrant value		1	%		2	%		4	%
Federal R&D tax grant		0	%		0	%		0	%
Other		0	%		0	%		0	%
Increase in valuation allowance		-46	%		-49	%		-54	%
Effective tax rate		0	%		0	%		0	%

Summary of Adjustments to Uncertain Tax Position

A summary of the company’s adjustments to its uncertain tax positions in the years ended December 31, 2013, 2012, and 2011 are as follows:

(in thousands)
Balance at December 31, 2010	$	275
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decreases for settlements with applicable taxing authorities		—
Decreases for lapses of statute of limitations		—
Balance at December 31, 2011	$	275
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decreases for settlements with applicable taxing authorities		—
Decreases for lapses of statute of limitations		—
Balance at December 31, 2012	$	275
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		(37	)
Decreases for settlements with applicable taxing authorities		—
Decreases for lapses of statute of limitations		—
Balance at December 31, 2013	$	238