Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

The following table summarizes the reporting of total stock-based compensation expense resulting from stock options, restricted stock units and the employee stock purchase plan (in thousands):



	Years Ended December 31,
	2019		2018

Research and development	$	1,168	$	518
Selling, general and administrative	5,316		1,210
Total stock-based compensation expense	$	6,484	$	1,728

Summary of Valuation Allowance [Table Text Block]

A reconciliation of the beginning and ending amounts of valuation allowances for the years ended December 31, 2019 and 2018 is as follows (in thousands):



Valuation allowance at December 31, 2017	$	(14,124	)
Increase for 2018 activity	(18,538		)
Valuation allowance at December 31, 2018	(32,662		)
Increase for 2019 activity	(36,288		)
Valuation allowance at December 31, 2019	$	(68,950	)

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the expected income tax benefit computed using the federal statutory income tax rate of 21% to the Company’s effective income tax rate is as follows:



	Years Ended December 31,
(in thousands)	2019			2018
Federal tax benefit at statutory rate	$	(26,468	)	$	(12,617	)
State tax benefit, net of federal benefit	(5,570		)	(1,842		)
Research and development and orphan drug credits	(2,912		)	(2,279		)
Uncertain tax positions	342			603
Permanent adjustments to expenses	169			45
Stock-based compensation	683			76
Return to provision adjustment	(3,278		)	(2,470		)
Rate impact of deferred tax balance	—			(63		)
Statutory rate differential	(51		)	—
Other	339			9
Changes in valuation allowance	36,288			18,538
Total income tax benefit	$	(458	)	$	—

Schedule of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows:



	December 31,
(in thousands)	2019			2018
Deferred tax assets:
Net operating losses	$	55,110		$	25,372
Federal research and orphan drug credits	8,309			5,426
Stock-based compensation	1,092			267
Other temporary differences	4,648			1,679
Valuation allowance	(68,950		)	(32,662		)
Total assets	209			82
Deferred tax liabilities:
Fixed and intangible assets	(155		)	(82		)
Other deferred tax liabilities	(54		)	—
Total liabilities	(209		)	(82		)
Net deferred tax assets	$	—		$	—