Stock Plans and Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

A summary of stock option activity under the 2010 Plan and inducement awards are summarized as follows:


	Number of Shares	Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding, December 31, 2021	10,363,769	$	3.80	7.41
Granted	4,313,500	3.21
Exercised	—	—
Canceled/Forfeited	(333,563)	8.39
Outstanding, March 31, 2022	14,343,706	$	3.51	7.95	$	7,333
Exercisable at March 31, 2022	6,884,853	$	3.31	6.76	$	5,247
Vested and unvested expected to vest at March 31, 2022	13,445,514	$	3.49	7.85	$	7,193

The weighted average grant date fair values of the stock options granted during the three months ended March 31, 2022 and 2021 were $2.62 and $9.13, respectively, and were calculated using the following estimated assumptions:


	Three Months Ended March 31,
	2022	2021
Expected term (years)	5.5	5.5


Risk free interest rate	1.4-1.7%	0.4-0.7%
Expected Volatility	110%-111%	107	%
Expected Dividends	None	None

Nonvested Restricted Stock Shares Activity

The following table presents a summary of unvested restricted stock awards (“RSAs”) under the 2010 Plan as of March 31, 2022:


	Number of Shares	Weighted Average Grant Date Fair Value
Unvested, December 31, 2021	10,312	$	3.45
Awarded	—	—
Vested	(10,312)	3.45
Forfeited	—	—
Unvested, March 31, 2022	—	$	—

Schedule Of Share Based Compensation Allocation Of Recognized Period Costs

For the three months ended March 31, 2022 and 2021, the Company recorded stock-based compensation expense to the following line items in its costs and expenses section of the Condensed Consolidated Statements of Operations and Comprehensive Loss, including expense related to its ESPP:


	Three Months Ended March 31,
(in thousands)	2022		2021
Research and development expenses	$	725	$	338
General and administrative expenses	993		761
Total stock-based compensation expense	$	1,718	$	1,099