Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of Reconciliation of Income Tax Expense Computed at Statutory Federal Income Tax Rate to Income Taxes

A reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the consolidated financial statements is as follows:

	Year Ended December 31,
	2019			2018			2017
	(In thousands)
Income tax benefit at federal statutory rate	$	(17,368	)	$	(7,899	)	$	(11,484	)
State taxes		(5,314	)		(2,340	)		(1,011	)
Tax credits		(2,910	)		(817	)		(222	)
Stock-based compensation		753			764			140
Federal tax rate change		—			—			2,202
Change in fair value of tranche rights		—			3			5,065
Other		25			241			—
Change in valuation allowance		24,850			10,074			5,310
Income tax expense	$	36		$	26		$	—
Effective tax rate		0.0	%		0.0	%		0.0	%

Schedule of Deferred Tax Assets and Liabilities

Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of deferred income taxes were as follows:

	As of December 31,
	2019			2018
	(In thousands)
Deferred tax assets:
Net operating losses	$	34,938		$	13,054
Capitalized license		771			835
Research credits		4,151			1,007
Accruals		401			514
Stock-based compensation		53			51
Net unrealized loss		—			11
Total gross deferred tax assets		40,314			15,472
Less valuation allowance		(40,221	)		(15,395	)
Total deferred tax assets		93			77
Deferred tax liabilities:
Net unrealized gain		13			—
Depreciation and amortization		80			77
Total gross deferred tax liability		93			77
Net deferred tax assets	$	—		$	—