Share-Based Payment Awards (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock Option Activity Under Plan

The following table provides a reconciliation of stock option activity under the Company’s equity incentive plans and for inducement awards for the year ended December 31, 2023:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding at January 1, 2023		4,082,555		$	13.79
Granted		2,923,861			4.76
Exercised		(260,321	)		11.33
Forfeited		(385,075	)		7.38
Expired		(56,253	)		26.71
Outstanding at December 31, 2023		6,304,767		$	9.98		7.89	$	85,536
Exercisable at December 31, 2023		2,325,480		$	15.61		6.31	$	20,178

Schedule of Key Assumptions Used

In determining the grant date fair value of option awards during the years ended December 31, 2023 and 2022, the Company applied the Black-Scholes option pricing model based on the following key assumptions:

	Year Ended	Year Ended
	December 31,	December 31,
	2023	2022
Option life (in years)	5.27 - 6.08	5.50 - 6.09
Stock volatility	78% - 97%	76% - 78%
Risk-free interest rate	3.44% - 4.68%	1.46% - 4.15%
Expected dividends	0.0%	0.0%

Summary of Information about Stock Options

The following table summarizes information about employee, non-executive director and external consultant stock options for the years ended December 31, 2023 and 2022 (in thousands except per share amounts):

	Year Ended		Year Ended
	December 31,		December 31,
	2023		2022
Weighted average grant date fair value per share	$	3.46	$	6.79
Total cash received from exercise of stock options		2,955		41
Total intrinsic value of stock options exercised		1,970		14

Summary of Restricted Stock Unit Activity

The following table provides a reconciliation of RSU activity under the 2016 Plan and the 2023 Plan for the year ended December 31, 2023:

	Number of Restricted Stock Units			Weighted Average Grant Date Fair Value
Nonvested at January 1, 2023		509,170		$	10.81
Granted		1,071,354			3.92
Vested		(201,414	)		11.04
Exercised		—			—
Forfeited		(45,918	)		8.60
Nonvested at December 31, 2023		1,333,192		$	5.31

Compensation Expense from Stock-Based Payment Awards

The Company’s consolidated statements of comprehensive loss included total compensation expense from stock-based payment awards for the years ended December 31, 2023 and 2022, respectively, as follows (in thousands):

	Year Ended		Year Ended
	December 31,		December 31,
	2023		2022
Research and development	$	4,650	$	6,130
Sales and marketing		289		1,650
General and administrative		7,118		6,397
Total stock-based compensation expense	$	12,057	$	14,177