Stock Plans and Stock-Based Compensation
As of December 31, 2025, the Company had two stockholder-approved, stock-based compensation plans: (i) the Fifth Amended and Restated 2010 Stock Incentive Plan, as amended (“2010 Plan”) and (ii) the Amended and Restated 2010 Employee Stock Purchase Plan, (“ESPP”). New employees are generally issued options as an inducement equity award under Nasdaq Listing Rule 5635(c)(4) outside of the 2010 Plan (“Inducement Awards”). In March 2026, stockholders approved the 2026 Incentive Plan.
The Fifth Amended and Restated 2010 Stock Incentive Plan, as amended
The 2010 Plan permits the granting of incentive and non-qualified stock options and stock awards to employees, officers, directors, and consultants of the Company and its subsidiary at prices determined by the Company’s board of directors. In May 2025, the Company's stockholders approved an amendment to the 2010 Plan to reserve an additional 1,255,000 shares of common stock for issuance under the 2010 Plan. The Company can issue up to 3,356,600 shares of its common stock pursuant to awards granted under the 2010 Plan. Options vest and become exercisable based on a schedule determined by the board of directors and expire up to ten years from the date of grant. The 2010 Plan uses a “fungible share” concept under which each share of stock subject to awards granted as options and stock appreciation rights (“SARs”) will cause one share per share under the award to be removed from the available share pool, while each share of stock subject to awards granted as restricted stock, restricted stock units, other stock-based awards or performance awards where the price charged for the award is less than 100% of the fair market value of the Company’s common stock will cause 1.3 shares per share under the award to be removed from the available share pool.
During the year ended December 31, 2025, the Company’s board of directors granted options to purchase 1,108,400 shares of the Company’s common stock to officers and employees of the Company under the 2010 Plan. These options vest and become exercisable as to 25% of the shares underlying the award after the first year and as to an additional 6.25% of the shares underlying the award in each subsequent quarter, based upon continued employment over a four-year period, and are exercisable at a price equal to the closing price of the Company’s common stock on the grant date.
During the year ended December 31, 2025, the Company’s board of directors granted 350,600 RSUs to employees of the Company under the 2010 Plan. These RSUs vest and become exercisable as to 25% of the shares underlying the award annually on the date of grant, based upon continued employment over a four-year period.
During the year ended December 31, 2025, the Company’s board of directors granted options to its non-employee directors to purchase 80,000 shares of common stock under the 2010 Plan, which will vest and become exercisable in one year from the date of grant. These options were granted at an exercise price equal to the closing market price of the Company’s common stock on the grant date.
As of December 31, 2025, 849,565 shares remained available for grant under the 2010 Plan.
Inducement Awards
The Company grants Inducement Awards to certain new employees. These options generally vest as to 25% of the shares underlying the option on the first anniversary of the grant date, and as to an additional 6.25% of the shares underlying the option on each successive quarter thereafter. During the year ended December 31, 2025, the Company’s board of directors granted Inducement Awards to purchase 284,750 shares of common stock. These options were granted at an exercise price that equaled the closing market price of the Company’s common stock on grant date.
Stock Options
A summary of stock option activity under the 2010 Plan and Inducement Awards are summarized as follows:
Number of
Options
Weighted
Average
Exercise
Price per
Share
Weighted
Average
Remaining Contractual Life
Aggregate Intrinsic Value
(000's)
Outstanding, December 31, 2024
1,160,251 $33.44 7.2$— 
Granted1,473,150 2.96 
Exercised— — 
Canceled(204,337)13.21 
Outstanding, December 31, 2025
2,429,064 $16.59 7.8$— 
Exercisable at December 31, 2025
823,010 $42.52 5.5$— 
Vested and unvested expected to vest at December 31, 2025
2,429,064 $16.59 7.8$— 
The weighted average grant date fair values of stock options granted during the years ended December 31, 2025 and 2024 were $2.08 and $9.50, respectively, and were calculated using the following estimated assumptions under the Black-Scholes option pricing model:
For the Year Ended
December 31,
20252024
Expected term (years)6.06.0
Risk-free interest rate
3.8-4.4%
3.9-4.5%
Expected volatility
113-114%
114-116%
Expected dividend yieldNoneNone
As of December 31, 2025, there was approximately $4.3 million of unrecognized compensation cost related to unvested employee stock option awards outstanding, which is expected to be recognized as expense over a weighted average period of 2.4 years. There were no employee stock options exercised during the year ended December 31, 2025.
Restricted Stock Awards
The following table presents a summary of outstanding RSAs under the 2010 Plan as of December 31, 2025:
Number of
Shares
Weighted
Average
Grant Date Fair Value
Unvested, December 31, 2024
40,137 $18.20 
Awarded— — 
Vested(39,637)18.20 
Forfeited(500)18.20 
Unvested, December 31, 2025
— $— 
The fair value of RSAs that vested during the year ended December 31, 2025 was $0.1 million.
Restricted Stock Units
The following table presents a summary of RSUs under the 2010 Plan as of December 31, 2025:
Number of SharesWeighted Average Grant Date Fair Value
Unvested, December 31, 2024— $— 
Awarded350,600 3.13 
Vested— 
Forfeited(93,200)3.13 
Unvested, December 31, 2025
257,400 3.13 
As of December 31, 2025, there was $0.6 million of unrecognized compensation costs related to RSUs, which are expected to be recognized as expense over a remaining weighted average period of 3.1 years.
2026 Incentive Plan
On March 17, 2026, the Company’s stockholders approved the Company’s 2026 Incentive Plan (the “2026 Plan”) under which awards may be made for up to a number of shares of common stock, $0.01 par value per share, of the Company (the “Common Stock”) equal to the sum of: (i) 6,407,374 shares of Common Stock; (ii) such additional number of shares of Common Stock (up to 3,474,867 shares) as is equal to the number of shares of Common Stock reserved for issuance under the 2010 Plan that remain available for grant under the 2010 Plan and the number of shares of Common Stock subject to awards granted under the 2010 Plan and the number of shares subject to awards granted under the inducement grant exception under Nasdaq Stock Market Rule 5635(c)(4) (“Inducement Awards”), in each case, that are outstanding as of the date of March 17, 2026 and which awards expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, and subject to the terms of the 2026 Plan; and (iii) an annual increase to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2027 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2036, equal to the lesser of (i) 5% of the sum of (a) the number of outstanding shares of Common Stock on such date, (b) the number of shares of Common Stock issuable upon conversion of any outstanding shares of convertible preferred stock of the Company (without giving effect to any restrictions or limitations on conversion) on such date, (c) the number of shares of Common Stock issuable upon the exercise of pre-funded warrants (without giving effect to any restrictions or limitations on conversion) issued by the Company as of such date, and (d) the number of shares subject to outstanding awards granted under the 2010 Plan, the Plan or as Inducement Awards as of such date and (ii) an amount determined by the Board. Awards in the form of “incentive stock options” may be granted with respect to a maximum of 25,000,000 shares of Common Stock under the 2026 Plan. No awards have been granted under the 2026 Incentive plan.
Amended and Restated 2010 Employee Stock Purchase Plan
The Company has reserved 500,000 shares of common stock for issuance under the ESPP. Eligible employees may purchase shares of the Company’s common stock at 85% of the lower closing market price of the common stock at the beginning of the enrollment period or ending date of the any purchase period within a two-year enrollment period, as defined.
The Company has four six-month purchase periods per each two-year enrollment period. If, within any one of the four purchase periods in an enrollment period, the purchase period ending stock price is lower than the stock price at the beginning of the enrollment period, the two-year enrollment resets at the new lower stock price. During the year ended December 31, 2025, 36,649 shares were issued under the ESPP. As of December 31, 2025, there were 357,814 shares available for future purchase under the ESPP.
For the years ended December 31, 2025 and 2024, the Company recorded immaterial compensation expense related to its ESPP and calculated the fair value of shares expected to be purchased under the ESPP using the Black-Scholes model.
Stock-Based Compensation Expense
For the years ended December 31, 2025 and 2024, the Company recorded stock-based compensation expense to the following line items in its costs and expenses section of the Consolidated Statements of Operations and Comprehensive Loss: 
For the Year Ended December 31,
20252024
Research and development expenses$1,771 $2,760 
General and administrative expenses2,247 3,167 
Total stock-based compensation expense$4,018 $5,927 
No income tax benefits have been recorded for the years ended December 31, 2025 and 2024, as the Company has recorded a full valuation allowance and management has concluded that it is more likely than not that the net deferred tax assets will not be realized (see Note 12, "Income Taxes").

Historical Timeline

Fiscal YearFiled
2025Mar 24, 2026Showing above
2024Mar 31, 2025
2023Feb 8, 2024
2022Mar 13, 2023
2021Feb 24, 2022
2020Mar 16, 2021

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.