Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation

Stock-Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

2016 Equity Incentive Plan

In April 2016, our board of directors adopted the 2016 Equity Incentive Plan, which was approved by our stockholders in May 2016 and which was subsequently amended and restated in May 2018 and August 2019 with the approval of our board of directors and our stockholders (the “2016 Third Amended Plan”). In June 2024, our board of directors approved a fourth amended and restated equity incentive plan, which was subsequently approved by the Company’s stockholders in August 2024 (the “2016 Fourth Amended Plan”). During the term of the 2016 Fourth Amended Plan, the share reserve will automatically increase on the first trading day in January of each calendar year ending on (and including) January 1, 2034, by an amount equal to 5% of the total number of outstanding shares of common stock and Series C Preferred Stock (determined on an as-converted stock basis) plus all outstanding prefunded warrants to acquire shares of common stock (if any) as of December 31st of the preceding calendar year. On January 1, 2024, pursuant to the terms of the 2016 Third Amended Plan, an additional 32,070 shares were made available for issuance. Upon approval of the 2016 Fourth Amended Plan on August 13, 2024, the number of shares available for issuance increased by 3,508,804 shares. As of September 30, 2024, there were 1,300,743 shares available for future issuance under the 2016 Fourth Amended Plan.

Option grants expire after ten years. Employee options typically vest over four years. Employees typically receive a new hire option grant, as well as an annual grant in the first or second quarter of each year. Options granted to directors typically vest either immediately or over a period of one or three years. Directors may elect to receive stock options in lieu of board compensation, which vest immediately. For stock options granted to employees and non-employee directors, the estimated grant date fair market value of the Company’s stock-based awards is amortized ratably over the individuals’ service periods, which is the period in which the awards vest. Stock-based compensation expense includes expense related to stock options, restricted stock units and employee stock purchase plan shares. The amount of stock-based compensation expense recognized for the three and nine months ended September 30, 2024 and 2023 was as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	762	$	371	$	1,250	$	1,028
General and administrative	1,086		582		1,698		1,673
Total stock-based compensation	$	1,848	$	953	$	2,948	$	2,701

Stock options with service-based vesting conditions

The Company has granted options that contain service-based vesting conditions. The compensation cost for these options is recognized on a straight-line basis over the vesting periods. A summary of option activity for the nine months ended September 30, 2024 is as follows:


	Options Outstanding
	Number of shares	Weighted average exercise price per share		Weighted average grant date fair value per share		Weighted average remaining contractual term (in years)
Balance at December 31, 2023	7,211	$	3,191.97	$	1,930.00	8.3
Granted	1,993,100	$	10.47	$	9.04


Forfeited	(27)	$	323.13	$	232.02
Expired	(228)	$	13,926.66	$	6,649.90
Balance at September 30, 2024	2,000,056	$	20.35	$	15.22	9.8

Exercisable at September 30, 2024	5,588	$	3,240.47	$	2,000.64	7.5

On August 13, 2024, as part of its annual stock option award, the Company granted options with service-based vesting conditions to purchase 1.4 million shares of common stock to its employees that vest over four years and options with service-based vesting conditions to purchase 0.1 million shares of common stock to its non-employee directors that vest over three years. Additionally, in June and July 2024, the Company granted 0.2 million options to each of its newly appointed Chief Legal Officer and newly appointed Chief Medical Officer. The options were granted as inducement option grants pursuant to Nasdaq Listing Rule 5635(c)(4) and are subject to service-based vesting conditions.

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. As of September 30, 2024, the aggregate intrinsic value of options outstanding was zero. There were 2,300 options that vested during the nine months ended September 30, 2024 with a weighted average exercise price of $1,164.22 per share. The total grant date fair value of shares which vested during the nine months ended September 30, 2024 was $1.9 million.

The Company recognized stock-based compensation expense of $1.4 million and $2.5 million related to stock options with service-based vesting conditions for the three and nine months ended September 30, 2024. At September 30, 2024, there was $18.4 million of total unrecognized compensation cost related to unvested service-based vesting condition awards. The unrecognized compensation cost is expected to be recognized over a weighted-average period of 3.3 years.

Stock-based compensation assumptions

The following table presents the assumptions used to compute stock-based compensation for stock options with service-based vesting conditions granted under the Black-Scholes valuation model for the nine months ended September 30, 2024.


Service-based options
Expected term of option (in years)						5.81 - 6.25
Expected stock price volatility						113.1% - 116.9%
Risk-free interest rate						3.70% - 4.26%
Expected annual dividend yield						0%

As of September 30, 2024, there were no outstanding stock options that contained market-based vesting conditions.

Restricted Stock Units

The Company has granted restricted stock units (“RSU”) that contain service-based vesting conditions. The Company measures the fair value of the RSUs using the stock price on the date of grant. The compensation cost for RSUs is recognized on a straight-line basis over the vesting period. A summary of RSU activity for the nine months ended September 30, 2024 is as follows:


	RSUs Outstanding
	Number of shares	Weighted average grant date fair value
Balance at Unvested RSUs at December 31, 2023	—	$	—
Granted	632,100	9.88

Unvested RSUs at September 30, 2024	632,100	$	9.88

The RSUs, which were granted on August 13, 2024, vest annually over a three-year period beginning on March 28, 2025. The Company recognized stock-based compensation expense of $0.4 million related to RSUs for the three and nine months ended September 30, 2024. At September 30, 2024, there was $5.8 million of total unrecognized compensation cost related to RSUs. The unrecognized compensation cost is expected to be recognized over a weighted-average period of 2.5 years.

Employee Stock Purchase Plan

On April 5, 2016, the Company’s board of directors approved the 2016 Employee Stock Purchase Plan, which was approved by the Company’s stockholders and became effective on May 18, 2016 (the “Initial ESPP”). In June 2024, our board of directors approved an amended and restated employee stock purchase plan, which was subsequently approved by the Company’s stockholders in August 2024 (the “ESPP”).

Under the ESPP, eligible employees can purchase common stock through accumulated payroll deductions at such times as are established by the administrator. The ESPP is administered by the compensation committee of the Company’s board of directors. Under the ESPP, eligible employees may purchase stock at 85% of the lower of the fair market value of a share of the Company’s common stock (i) on the first day of an offering period or (ii) on the purchase date. Eligible employees may contribute up to 15% of their earnings during the offering period. The Company’s board of directors may establish a maximum number of shares of the Company’s common stock that may be purchased by any participant, or all participants in the aggregate, during each offering period. Under the ESPP, a participant may not accrue rights to purchase more than $25,000 of the fair market value of the Company’s common stock for each calendar year in which such right is outstanding.

The Company initially reserved and authorized up to 174 shares of common stock for issuance under the Initial ESPP. Pursuant to the ESPP, on January 1 of each calendar year, the aggregate number of shares that may be issued under the ESPP automatically increases by a number equal to 1% of the Company’s outstanding shares of common stock and Series C Preferred Stock (determined on an as-converted basis) plus all outstanding prefunded warrants to acquire shares of common stock (if any), as of December 31st of the preceding calendar year. On January 1, 2024, pursuant to the Initial ESPP the number of shares available for issuance increased by 174. Upon approval of the ESPP on August 13, 2024, the number of shares available for issuance increased by 233,920 shares. As of September 30, 2024, 234,878 shares remained available for issuance.

In accordance with the guidance in ASC 718-50, Employee Share Purchase Plans, the ability to purchase shares of the Company’s common stock at the lower of the offering date price or the purchase date price represents an option and, therefore, the ESPP is a compensatory plan under this guidance. Accordingly, stock-based compensation expense is determined based on the option’s grant-date fair value and is recognized over the requisite service period of the option. The Company used the Black-Scholes valuation model and recognized minimal stock-based compensation expense for the three and nine months ended September 30, 2024.