The Company adopted the 2016 Equity Incentive Plan, as amended (the “2016 Plan”) on March 31, 2016. The 2016 Plan provided for the granting of stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock awards to employees, directors and non-employees. All option awards were granted with an exercise price equal to or greater than the market price of the Company’s stock at the date of grant. Option awards generally vest over three to four years. Certain option awards provide for accelerated vesting if there is a change in control as defined in the 2016 Plan. The provisions of the 2016 Plan allow for early exercises for options that have not yet vested. Early exercises have historically been for a de minimis number of shares.

On September 23, 2020, the Company adopted the 2020 Equity Incentive Plan (the “2020 Plan”), which became effective upon the execution of the underwriting agreement related to the IPO and serves as the successor to the 2016 Plan. The 2020 Plan authorizes the award of stock options, restricted stock awards, stock appreciation rights, restricted stock units, cash awards, performance awards and stock bonus awards. The number of shares reserved for issuance under the 2020 Plan increases automatically on January 1 of each fiscal year, through and including January 1, 2030, by the number of shares equal to 5% of the aggregate number of outstanding shares of common stock as of the immediately preceding December 31, or a lesser number of shares as may be determined by the board of directors (or an authorized committee thereof). On January 1, 2022, the board of directors authorized an increase in the number of shares reserved for issuance under the 2020 Plan by 1,292,458 shares of common stock.

At June 30, 2022, there were 1,880,377 shares of common stock available for issuance under the 2020 Plan.

On September 23, 2020, the Company adopted the 2020 Employee Stock Purchase Plan (the "ESPP"), which became effective upon the execution of the underwriting agreement related to the IPO. The Company initially reserved 280,000 shares of common stock for sale under the ESPP. The aggregate number of shares reserved for sale under the ESPP increases automatically on January 1st of each fiscal year through and including January 1, 2030, by the number of shares equal to the lesser of (a) 1% of the total number of shares of common stock outstanding on the last day of the fiscal year prior to the date of such automatic increase and (b) 560,000 shares, provided that prior to the date of any such increase, the board of directors may determine a lesser number of shares for such increase. In December 2021, the board of directors determined that there would be no automatic increase in the number of shares of common stock reserved under the ESPP on January 1, 2022. The ESPP provides for six-month offering periods commencing on January 1 and ending on June 30 and commencing on July 1 and ending on December 31 of each calendar year. The Company began its first offering period on January 1, 2022, and issued 89,112 shares of common stock on June 30, 2022 at the end of the offering period.

Total stock-based compensation was classified as follows on the unaudited interim condensed consolidated statements of operations (in thousands):


	THREE MONTHS ENDED JUNE 30,				SIX MONTHS ENDED JUNE 30,
	2022		2021		2022		2021

General and administrative	$	1,476	$	1,029	$	2,738	$	1,768
Research and development		704		627		1,422		1,060
Total stock-based compensation	$	2,180	$	1,656	$	4,160	$	2,828

In December 2020, the Company granted an employee an option to purchase 113,000 shares of the Company’s common stock with an exercise price per share equal to the fair value of the Company’s common stock on the date of grant. This grant is included in the outstanding options in the summary table below. The option grant includes three separate tranches (each tranche representing one-third of the total grant) that will each vest four years from the date of grant. This option grant and its tranches are subject to accelerated vesting in the event that the Company achieves certain defined milestones related to the Company’s manufacturing efforts. As of June 30, 2022, the Company determined that the requisite service period for two of the three tranches of this award is four years and recognized $0.2 million of stock-based compensation expense for the six months ended June 30, 2022. Accelerated vesting was considered to be probable for one of the tranches as of June 30, 2022. Accordingly, the Company recognized stock-based compensation expense of $0.2 million for this tranche in the six months ended June 30, 2022, which included a cumulative adjustment reflecting the retroactive application of the accelerated vesting.

A summary of option activity for the six months ended June 30, 2022 is presented below:


	SHARES			WEIGHTED AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (YEARS)		AGGREGATE INTRINSIC VALUE (IN THOUSANDS)
Outstanding at December 31, 2021		3,681,793		$	10.84
Granted		1,723,500		$	1.75
Exercised		(34,863	)	$	1.77
Canceled, expired or forfeited		(181,652	)	$	8.34
Outstanding at June 30, 2022		5,188,778		$	7.97		8.29	$	33
Vested and expected to vest at June 30, 2022		5,188,778		$	7.97		8.29	$	33
Exercisable at June 30, 2022		1,670,042		$	7.73		6.98	$	25

The weighted average grant date fair value per share of options granted to employees, directors and non-employee consultants during the six months ended June 30, 2022 and 2021 was $1.28 and $11.69, respectively. The total intrinsic value of options exercised was $0.02 million and $1.7 million for the six months ended June 30, 2022 and 2021, respectively. Total unrecognized stock-based compensation expense related to options is $17.1 million at June 30, 2022, and is expected to be recognized over a weighted-average period of 2.7 years.