Stock-Based Compensation

3 Months Ended

Mar. 31, 2021

9. Stock-Based Compensation

The Company recognized stock-based compensation expense on all employee and

non-employee

awards as follows:


	For the three months ended March 31,
(in thousands)	2021		2020
Research and development	$	733	$	530
General and administrative		1,464		1,410

Stock-based compensation expense	$	2,197	$	1,940

The Company granted an aggregate of 4,314,438 stock options during the three months ended March 31, 2021 with a weighted-average grant date fair value of $2.43 per share. The Company granted an aggregate of 896,000 stock options during the three months ended March 31, 2020 with a weighted average grant date fair value of $2.64 per share.

On March 4, 2021, the Company extended the contractual life of 216,700 fully vested stock options held by a

former

director of the

Company, in conformity with prior practice. These extensions resulted in additional stock

compensation expense of approximately $82 thousand

during

the three months ended March 31, 2021.

For the three months ended March 31, 2021 and 2020, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions:


	For the three months ended March 31,
	2021	2020
Risk-free interest rate	0.09 - 1.05%	0.36 - 0.39%
Expected life in years	5.50 - 6.25	5.75 - 6.25
Expected volatility	72.92 - 74.20%	73.59 - 74.18%
Expected dividend yield	0%	0%

At March 31, 2021, there were 463,333 stock options that

had been issued outside the 2012 Equity Incentive Plan, or the 2012 Plan and the 2020 Equity Incentive Plan, or the 2020 Plan. These options are excluded from the schedule below.

Stock option activity under the Company’s stock option plans for the three months ended March 31, 2021 is as follows:


(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding, December 31, 2020		6,840,719		$	3.81
Granted		4,314,438			3.79
Exercised		(352,442	)		2.89
Cancelled		(84,337	)		3.53

Outstanding, March 31, 2021		10,718,378		$	3.83		13.40	$	4,926

Options exercisable, March 31, 2021		3,562,744		$	4.23		6.68	$	2,176

Options exercisable, December 31, 2020		3,596,315		$	4.17		6.90	$	598

Options available for future grant		1,267,888

At March 31, 2021, total unrecognized compensation costs related to unvested stock options outstanding amounted to $16.0 million. The cost is expected to be recognized over a weighted-average period of 1.85 years.

A summary of the status of unvested restricted stock for the three months ended March 31, 2021 is as follows:


	Number of Shares		Weighted-Average Grant Date Fair Value
Unvested, December 31, 202 0		786,280	$	3.08
Granted		313,326		4.31
Vested		—		—
Cancelled		—		—

Unvested, March 31, 2021		1,099,606	$	3.43

At March 31, 2021, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $2.6 million. The cost is expected to be recognized over a weighted-average period of 1.57 years.

At the Company’s annual meeting held on June 29, 2020, the shareholders approved the 2020 Equity Incentive Plan, or the 2020 Plan, which is a successor to and continuation of the 2012 Plan. The 2020 Plan had

21 million shares authorized, plus the shares remaining for issuance under the 2012 Plan. Our ability to utilize the total shares authorized under the 2020 Plan will be limited by the total number of shares authorized in our certificate of incorporation.

As a result, as of March 31, 2021,

there are 1,287,888 shares available to grant from the 2020

lan. No additional awards can be granted from the 2012 Plan or the Company’s 2003 Stock Option Plan.