Share-based compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-based compensation

Schedule of share based compensation expense

The Company recorded share‑based compensation expense in the following expense categories of its condensed consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Research and development expenses	$	522	$	291	$	1,195	$	399
General and administrative expenses		797		614		2,245		782
	$	1,319	$	905	$	3,440	$	1,181

Schedule of share option activity

				Weighted
		Weighted		Average	Aggregate
	Number of	Average		Contractual	Intrinsic
	Shares	Exercise Price		Term	Value
				(in years)	(in thousands)
Outstanding as of December 31, 2019	2,634,346	$	9.57	9.04	$	2,868
Granted	1,174,434		10.88	—		—
Exercised	(5,071)		2.29	—		—
Forfeited	(149,697)		10.72	—		—
Outstanding as of June 30, 2020	3,654,012	$	9.91	8.94	$	21,378
Vested and expected to vest as of June 30, 2020	3,654,012	$	9.91	8.94	$	21,378
Options exercisable as of June 30, 2020	1,168,098	$	8.06	8.18	$	9,655

Schedule of assumptions used to determine the fair value of share options granted

	Three				Six
	Months				Months
	Ended				Ended
	June 30,				June 30,
	2020		2019		2020		2019
Risk-free interest rate	0.4	%	2.2	%	1.5	%	2.2
Expected volatility	76.8	%	78.0	%	74.1	%	78.1
Expected dividend yield	—		—		—		—
Expected term (in years)	6.1		5.8		6.0		5.9