Share-Based Payment Awards (Tables)

6 Months Ended

Jun. 30, 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 plan and for inducement awards for the six months ended June 30, 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		2,426,695			3.47
Exercised		(880	)		5.80
Forfeited		(305,386	)		6.09
Expired		(32,016	)		22.72
Outstanding at June 30, 2023		6,170,968		$	10.07		8.20	$	12,265
Exercisable at June 30, 2023		2,252,047		$	16.15		6.64	$	80

Schedule of Key Assumptions Used

In determining the grant date fair value of option awards during the six months ended June 30, 2023, the Company applied the Black-Scholes option pricing model based on the following key assumptions:

Option life (in years)	5.27 - 6.08
Stock volatility	78% - 88%
Risk-free interest rate	3.44'% - 3.95%
Expected dividends	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 six months ended June 30, 2023 (in thousands except per share amount):

	Six Months
	Ended
	June 30, 2023
Weighted average grant date fair value per share	$	2.45
Total cash received from exercise of stock options		5
Total intrinsic value of stock options exercised		1

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 six months ended June 30, 2023:

	Number of Restricted Stock Units			Weighted Average Grant Date Fair Value
Nonvested at January 1, 2023		509,170		$	10.81
Granted		980,520			3.42
Vested		(199,414	)		11.07
Forfeited		(30,057	)		10.56
Nonvested at June 30, 2023		1,260,219		$	5.03

Compensation Expense from Stock-Based Payment Awards

The Company’s condensed consolidated statements of comprehensive loss included total compensation expense from stock-based payment awards as follows (in thousands):

	Three Months Ended June 30,					Six Months Ended June 30,
	2023			2022		2023		2022
Compensation expense included in:
Research and development	$	902		$	2,011	$	2,142	$	3,485
Sales and marketing		(200	)		496		230		905
General and administrative		1,086			1,633		2,466		3,227
	$	1,788		$	4,140	$	4,838	$	7,617