The Company has three stock-based incentive compensation plans collectively referred to as the Equity Plans. The Company also has an employee stock purchase plan, the 2021 ESPP.

The Company’s 2006 Stock Plan was originally adopted by the Company's Board and approved by the Company’s stockholders in 2006. The Company’s 2006 Plan was terminated in 2015 in connection with the adoption of the Company’s 2015 Plan and as a result no new awards may be issued under the 2006 Plan. However, the 2006 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2006 Plan.

The Company’s 2015 Plan was originally adopted by the Company’s Board and approved by the Company’s stockholders in 2015. The 2015 Plan was most recently amended in March 2021. In July 2021, upon completion of the IPO, the 2015 Plan terminated immediately prior to effectiveness of the 2021 Plan with respect to the grant of future awards. However, the 2015 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2015 Plan.

On July 28, 2021, the Company’s 2021 Plan was adopted and approved by the Company’s Board and stockholders and became effective. The 2021 Plan provides for the grant of incentive stock options to employees and any subsidiary corporations’ employees, and for the grant of nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, or (“RSUs”), and performance awards to employees, directors, and consultants and subsidiary corporations’ employees and consultants. The number of shares of the Company’s common stock available for issuance under the 2021 Plan is equal to 2,420,135 shares of common stock plus any shares subject to awards granted under the 2015 Plan and the 2006 Plan that, after the effectiveness of the 2021 Plan, expire or otherwise terminate without having been exercised in full, are tendered to or withheld by the Company for payment of an exercise price or for tax withholding obligations, or are forfeited to or repurchased by the Company due to failure to vest, with the maximum number of shares to be added to the 2021 Plan from the 2015 Plan and 2006 Plan being equal to 4,569,530 shares of common stock.

The number of common shares reserved for issuance under the 2021 Plan will be increased automatically on the first day of each fiscal year beginning with the 2022 fiscal year and ending on the ten year anniversary of the date the Board approved the 2021 Plan, by a number equal to the least of: (i) 7,260,406 shares of the Company's common stock; (ii) 4% of the outstanding shares of common stock on the last day of the Company's immediately preceding fiscal year; or (iii) such lesser number of shares of the Company's common stock as the administrator may determine. The 2021 Plan is administered by the Company’s Board.

On July 28, 2021, the Company’s Board and stockholders adopted and approved the Company’s 2021 ESPP. There are 711,643 shares of the Company’s common stock available for issuance under the 2021 ESPP.

The 2021 ESPP provides eligible employees of the Company and its subsidiaries with the opportunity to purchase shares of the Company’s common stock at a purchase price equal to 85% of the common stock’s fair market value on the first trading day or last trading day of each purchase period, whichever is lower. The 2021 ESPP provides for two six-month purchase periods every twelve months: May 1 through October 31 and November 1 through April 30. The initial purchase period began on November 1, 2021.

The number of common shares reserved for issuance under the 2021 ESPP are increased automatically on the first day of each fiscal year beginning with the Company's 2022 fiscal year, by a number equal to the least of: (i) 1,452,081 shares; (ii) 1% of the outstanding shares of common stock on the last day of the Company's immediately preceding fiscal year; or (iii) such other amount as the administrator may determine. The 2021 ESPP is administered by the Board.

On March 8, 2022, the Company filed on a Form S-8 registration statement under the Securities Act to register the offer and sale of 1,094,670 additional shares of common stock under the 2021 Plan and 273,667 shares of common stock under the 2021 ESPP.

A summary of stock option activities for the six months ended June 30, 2022 is as follows:


	Number of Options			Weighted Average Exercise Price		Weighted Avg Remaining Contractual Life (Years)
Options outstanding as of December 31, 2021		5,754,005		$	11.64		5.20
Issued
Granted		782,557			12.46
Exercised		(140,826	)		4.16
Forfeited		(83,717	)		14.69
Expired		(88,909	)		17.07
Options outstanding as of June 30, 2022		6,223,110			11.80		6.84
Exercisable as of June 30, 2022		3,515,831		$	10.00		5.18

A summary of non-vested restricted stock unit activities for the six months ended June 30, 2022 is as follows:


				Weighted
				Average
	Number of			Grant Date
	Shares			Fair Value

Unvested at December 31, 2021		640,479		$	15.46
Granted		80,427			13.37
Vested		(104,839	)		15.64
Forfeited		(30,619	)		15.38
Unvested at June 30, 2022		585,448		$	15.14

As of June 30, 2022 and December 31, 2021, the intrinsic value of options vested was $19.1 million and $14.7 million, respectively, and of all options outstanding was $21.3 million and $14.7 million, respectively. During the six months ended June 30, 2022 and 2021, the total cash received from the exercise of stock options was $0.6

million and $1.2 million, respectively. The total fair value less strike price of these options was $1.2 million and $3.1 million, respectively.

Stock-based compensation expense was classified in the accompanying condensed consolidated statements of operations and comprehensive income (loss) as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	792	$	540	$	1,566	$	1,137
Selling, general and administrative		1,866		686		3,520		1,149
Cost of goods sold		246		180		467		359
	$	2,904	$	1,406	$	5,553	$	2,645

As of June 30, 2022 and December 31, 2021, there were 2,707,279 and 2,437,649 unvested options, respectively. Total unrecognized expense related to unvested stock options was approximately $21.0 million and $20.1 million as of June 30, 2022 and December 31, 2021, respectively. Amounts are expected to be recognized over a weighted average period of approximately 2.9 and 3.0 years, respectively.

As of June 30, 2022, there was $8.0 million of total unrecognized compensation costs, adjusted for any forfeitures, related to non-vested restricted stock units granted under the 2021 Plan. The unrecognized compensation cost is expected to be recognized over a weighted average period of 2.9 years.

The following table presents the range and weighted-average assumptions, used in the Black-Scholes option pricing model to determine the fair value of stock options:


	Six Months Ended June 30,
	2022		2021
	Range	Weighted Average	Range	Weighted Average
Expected volatility	62.4% to 63.4%	62.7%	62.3% to 63.7%	63.6%
Risk-free interest rate	2.0% to 3.0%	2.2%	0.6% to 1.6%	1.1%
Expected life (in years)	6.0 to 10.0 years	6.1 years	5.52 to 10.00 years	6 years
Expected dividend yield	0.0%	0.0%	0.0%	0.0%
Grant date fair value	$10.74 to $12.85	$12.32	$15.60 to $19.94	$15.64

Each share of common stock is entitled to one vote. Common stock reserved for future issuance consisted of the following:


	June 30, 2022		December 31, 2021
Stock options issued and outstanding under the Equity Plans		6,223,110		5,754,005
Restricted stock units		585,448		640,479
Employee stock purchase plan		711,643		484,027
Total shares of common stock reserved		7,520,201		6,878,511

On January 3, 2022, the Board approved the issuance of 19,196 restricted stock units to a non-employee director. The award will vest over three years of service.

On June 2, 2022, the Company issued automatic annual awards of 61,231 restricted stock units to seven non-employee directors related to their continued service on the Board. The awards will vest over one year of service.