Share-based compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-based compensation

Schedule of Stock-based compensation expense

Share-based compensation expense recorded as research and development and general and administrative expenses in the statements of operations is as follows (in thousands):

	Year Ended December 31,
In thousands)	2022		2021
General and administrative	$	3,471	$	2,071
Research and development		1,861		1,377
	$	5,332	$	3,448

Weighted average assumptions used in option-pricing

The weighted average assumptions used in the Black-Scholes option-pricing model for stock options granted were:

	Year ended December 31,
	2022			2021
Expected volatility		85.6	%		83.0	%
Risk-free interest rate		2.7	%		1.0	%
Expected term (in years)		6.0			6.0
Expected dividend yield		—			—
Fair value of common stock	$	3.63		$	23.04

Summary of option activity

				Weighted
		Weighted		average
		average		remaining
	Number of	exercise price		contractual
	shares	per share		term (years)
Outstanding at January 1, 2022	2,005,756	$	11.26	8.50
Granted	563,900		3.63	9.19
Forfeited	(24,990)		11.97	—
Expired	(6,791)		17.54	—
Exercised	(18,470)		1.76	6.62
Outstanding at December 31, 2022	2,519,405		9.60	7.90
Exercisable at December 31, 2022	1,239,114		8.86	7.30