Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of the Federal Statutory Income Tax Rate and the Company's Effective Income Tax Rate

A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2018			2017			2016
Federal statutory income tax rate		(21.0	)%		(34.0	)%		(34.0	)%
State income taxes		(8.6	)		(6.9	)		(6.7	)
Research and development tax credits		(4.7	)		(3.4	)		(2.8	)
Stock-based compensation		(0.6	)		3.6			1.9
Change in U.S. tax rate		-			18.7			-
Change in valuation allowance		34.9			22.0			41.6
Effective income tax rate		-	%		-	%		-	%

Summary of Company's Net Deferred Tax Assets (Liabilities)

The Company’s net deferred tax assets (liabilities) consisted of the following:

	December 31,
	2018			2017
	(in thousands)
Deferred tax assets:
Intangibles, including acquired in-process    research and development	$	1,201		$	1,303
Capitalized start-up costs		463			502
Net operating loss carryforwards		34,234			9,406
Research and development credit carryforwards		11,766			5,817
Deferred revenue		12,199			15,913
Equity-based compensation		4,064			3,248
Accruals and allowances		1,359			1,112
Gross deferred tax assets		65,286			37,301
Deferred tax asset valuation allowance		(64,046	)		(35,372	)
Total deferred tax assets		1,240			1,929
Deferred tax liabilities:
Fixed assets		(1,240	)		(1,929	)
Total deferred tax liabilities		(1,240	)		(1,929	)
Net deferred tax asset (liability)	$	-		$	-