Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity for all of our plans during 2019:

	2017 Plan			2019 Inducement Plan		Total Number of Stock Options
Outstanding as of December 31, 2018		2,297,810			—		2,297,810
Granted		870,434			171,300		1,041,734
Exercised		(78,610	)		—		(78,610	)
Forfeited or cancelled		(291,506	)		—		(291,506	)
Outstanding as of December 31, 2019		2,798,128			171,300		2,969,428

The following table summarizes details regarding stock options granted under our equity incentive plans for the year ended December 31, 2019:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2018		2,297,810		$	8.03		8.77	$	354
Granted		1,041,734			8.25		—		—
Exercised		(78,610	)		6.46		—		—
Forfeited or cancelled		(291,506	)		8.21		—		—
Outstanding as of December 31, 2019		2,969,428		$	8.13	7.94		$	6,689
Outstanding as of December 31, 2019 - vested and expected to vest		2,969,428		$	8.13	7.94		$	6,689
Exercisable at December 31, 2019		1,339,002		$	7.56	7.08		$	3,566

Summary of Assumptions Used to Determine Fair Value of Stock Option Awards Granted to Employees and Directors

The assumptions that the Company used in the Black-Scholes option-pricing model to determine the fair value of stock option awards granted to employees and directors were as follows, presented on a weighted average basis:

	Year Ended December 31,
	2019			2018
Risk-free interest rate		2.4	%		2.7	%
Expected term (in years)		6.3			6.3
Expected volatility		75.2	%		74.1	%
Expected dividend yield		0.0	%		0.0	%

Summary of Share-Based Compensation Expense

The Company recorded share-based compensation expense, for both incentive units and stock options in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands):

	Year Ended December 31,
	2019		2018
Research and development expenses	$	1,580	$	1,072
General and administrative expenses		2,196		1,677
Total	$	3,776	$	2,749