The Company’s Board of Directors adopted and the Company’s stockholders approved, effective on the day prior to the effectiveness of the registration statement on Form S-1 related to the IPO, an amendment and restatement of the 2018 Omnibus Incentive Plan (the 2018 Plan) which provides for the grant of incentive stock options, within the meaning of Section 422 of the Code to employees, and for the grant of nonstatutory stock options, restricted stock, restricted stock units (RSUs), stock appreciation rights, performance units, and performance shares to employees, directors, and consultants of the Company.

Options granted under the 2018 Plan expire no later than 10 years from the date of grant. The exercise price of options granted under the 2018 Plan must at least be equal to the fair market value of the Company’s common stock on the date of grant. With respect to any participant who owns more than 10% of the voting power of all classes of the Company’s outstanding stock, the term of an incentive stock option granted to such participant must not exceed five years and the exercise price must equal at least 110% of the fair market value on the grant date. Employee stock options generally vest 25% upon one year of continued service to the Company, with the remainder in monthly increments over three additional years.

Subject to an annual evergreen increase and adjustment in the case of certain capitalization events, the Company initially reserved 4,384,000 shares of the Company’s common stock for issuance pursuant to awards under the 2018 Plan. The 2018 Plan is administered by the Compensation Committee of the Company’s Board of Directors. The number of shares of the Company’s common stock available for issuance under the 2018 Plan will also include an annual increase on the first day of each fiscal year beginning with the 2020 fiscal year, equal to the least of (i) 8,768,800 shares, (ii) 4% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Company’s Board of Directors. Effective January 1, 2020, the number of shares of common stock available under the 2018 Plan increased by 964,487 shares pursuant to the evergreen provision of the 2018 Plan. As of June 30, 2020, 2,855,052 shares of common stock remained available for issuance under the 2018 Plan.

The 2010 Stock Plan (the 2010 Plan) was originally adopted by the Company’s Board of Directors and approved by the Company’s stockholders in November 2010. The 2010 Plan was amended and restated in December 2017 and April 2019. The 2010 Plan allowed the Company to provide incentive stock options, within the meaning of Section 422 of the Code, nonstatutory stock options and stock purchase rights to eligible employees, consultants and directors and any parent or subsidiary of the Company. The 2010 Plan was terminated in 2019 and the Company will not grant any additional awards under the 2010 Plan. However, the 2010 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2010 Plan.

The Company’s Board of Directors adopted and the Company’s stockholders approved, effective on the day prior to the effectiveness of the registration statement on Form S-1 related to the IPO, the 2019 Employee Stock Purchase Plan (ESPP). The ESPP is intended to have two components: a component that is intended to qualify as an “employee stock purchase plan” under Section 423 of the Code (the 423 Component) and a component that is not intended to qualify (the Non-423 Component). The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock at the beginning of the offering period or at the end of each applicable purchase period.

Subject to adjustment in the case of certain capitalization events, a total of 280,000 common shares of the Company were available for purchase at adoption of the ESPP. Pursuant to the ESPP, the annual share increase pursuant to the evergreen provision is determined based on the least of (i) 560,000 shares, (ii) 1% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Company’s Board of Directors. Effective January 1, 2020, the number of shares of common stock available under the ESPP increased by 241,121 shares pursuant to the evergreen provision of the ESPP. During the six months ended June 30, 2020, the Company issued 23,295 shares of common stock under the ESPP. As of June 30, 2020, 497,826 shares of common stock remained available for issuance under the ESPP.

Total stock-based compensation expense recorded related to the 2010 Plan, 2018 Plan, and ESPP was recorded in the condensed statements of operations and allocated as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Research and development	$	1,047	$	109	$	1,713	$	214
General and administrative		908		32		1,565		66
Total stock-based compensation expense	$	1,955	$	141	$	3,278	$	280

Accrued stock-based compensation expense for awards where the service inception date precedes grant date was $0.1 million and $0, for the three months ended June 30, 2020 and 2019, respectively. Accrued stock-based compensation expense for awards where the service inception date precedes grant date was $0.1 million and $0, for the six months ended June 30, 2020 and 2019, respectively.


	Number of Shares			Weighted- Average Exercise		Weighted- Average Remaining Contractual Term (Years)
Balance—December 31, 2019		2,289,209		$	3.36		8.1
Granted		804,975		$	42.64
Exercised		(94,303	)	$	1.31
Cancelled		(25,334	)	$	15.96
Balance—June 30, 2020		2,974,547		$	13.95		8.2
Exercisable—June 30, 2020		1,180,003		$	2.90		6.7

There were no options granted during the three months ended June 30, 2019. The fair value of employee stock options was estimated using the following weighted-average assumptions:

	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2020			2019		2020			2019
Expected term in years		6.1			—		6.0			6.0
Expected volatility		86.5	%		—		83.9	%		79.3	%
Risk-free interest rate		0.5	%		—		1.1	%		2.5	%
Dividend yield		—			—		—			—
Weighted average fair value of share-based awards granted	$	41.1		$	—	$	30.1		$	1.0

The fair value of ESPP was estimated using the following weighted-average assumptions:

	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2020			2019		2020			2019
Expected term in years		0.5			—		0.5			—
Expected volatility		100.1	%		—		100.1	%		—
Risk-free interest rate		0.2	%		—		0.2	%		—
Dividend yield		—			—		—			—

During December 2018, the Company issued 116,518 shares of common stock to an executive officer under a restricted stock agreement at a grant date fair value of $1.39 per share that vests over two years. Any unvested shares are subject to forfeiture in the case that the grantee’s service terminates. As of June 30, 2020, 58,259 shares of restricted stock were vested. For the three and six months ended June 30, 2020, the related stock-based compensation was immaterial. As of June 30, 2020, there was an immaterial amount of unrecognized stock-based compensation related to restricted stock, which the Company expects to recognize over a remaining weighted-average period of 0.1 years.

During the three and six months ended June 30, 2020, the Company issued and released 1,828 shares of restricted stock units (RSU) with a weighted-average grant date fair value of $51.30 per share to certain members of the Company’s Board of Directors under the Company’s Outside Director Compensation Policy. These RSUs were fully vested upon issuance. During the three and six months ended June 30, 2020, there were no shares of restricted stock units cancelled. The stock-based compensation expense related to these awards was $0.1 million, which was recognized over the service period of the awards. As of June 30, 2020, there is no remaining amount of unrecognized stock-based compensation related to these awards.