| Stock Option Plans and Warrants to Purchase Common Stock |
Note 8. Stock Option Plans and Warrants to Purchase Common Stock Stock Option Plans The Amended and Restated 2005 Equity Incentive Plan (“2005 Plan”) was replaced by the 2015 Plan, which was approved in June 2015. No securities are available for future issuance under the 2005 Plan. The 2015 Plan was replaced by the 2025 Plan, which was approved in June 2025. No securities are available for future issuance under the 2015 Plan. As of December 31, 2025, there are 5,309,912 shares currently available for grants under the 2025 Plan. The plan is divided into four separate equity programs: | 1) | the Discretionary Option Grant Program, under which eligible persons may, at the discretion of the Plan Administrator, be granted options to purchase shares of common stock, |
| 2) | the Salary Investment Option Grant Program, under which eligible employees may elect to have a portion of their base salary invested each year in options to purchase shares of common stock, |
| 3) | the Automatic Option Grant Program, under which eligible nonemployee Board members will automatically receive options at periodic intervals to purchase shares of common stock, and |
| 4) | the Director Fee Option Grant Program, under which non-employee Board members may elect to have all, or any portion, of their annual retainer fee otherwise payable in cash applied to a special option grant. |
Shares available for grant under the 2025 Plan were as follows: | | | Shares available for grant at plan approval | | 6,000,000 | Shares granted | | (20,000) | Options granted | | (670,088) | Shares available for grant at December 31, 2025 | | 5,309,912 |
The number of shares reserved for issuance under the 2025 Plan automatically increases pursuant to the terms thereof on January 1 of each year, from January 1, 2026 through January 1, 2035. Pursuant to the terms of the 2025 Plan, the number of shares reserved for issuance under the plan increased by 403,446 as of January 1, 2026, for a total number of shares reserved for issuance under the plan of 6,403,446. Option activity for the years ended December 31, 2025 and 2024: | | | | | | | | | | Weighted | | | | | Average | | | | | Exercise | | | Options | | Price | Balance outstanding at December 31, 2023 | | 56,609 | | $ | 90.58 | Granted | | 173,740 | | | 3.35 | Forfeited | | (430) | | | 1,549.28 | Balance outstanding at December 31, 2024 | | 229,919 | | $ | 21.94 | Granted | | 670,088 | | | 1.64 | Forfeited | | (6,652) | | | 96.46 | Balance outstanding at December 31, 2025 | | 893,355 | | $ | 6.15 |
The weighted-average exercise price, by price range, for outstanding options to purchase common stock at December 31, 2025 was: | | | | | | | | | Weighted | | | | | | | Average | | | | | | | Remaining | | | | | | | Contractual | | Outstanding | | Exercisable | Price Range | | Life in Years | | Options | | Options | $1.37 - $10.78 | | 9.62 | | 882,107 | | 321,844 | $129.60 - $640.80 | | 4.83 | | 11,168 | | 11,168 | $1,776.00 | | 0.46 | | 80 | | 80 | Total | | 9.56 | | 893,355 | | 333,092 |
The Company’s share-based compensation expense for the years ended December 31, 2025 and 2024 was recognized as follows: | | | | | | | Share-based compensation | | 2025 | | 2024 | Research and development | | $ | 204,848 | | $ | 131,917 | General and administrative | | | 382,735 | | | 197,898 | Total | | $ | 587,583 | | $ | 329,815 |
At December 31, 2025, the total compensation cost for stock options not yet recognized was approximately $973,000 and will be recognized over the next three years. Warrants to Purchase Common Stock Warrant activity for the years ended December 31, 2025 and 2024 was as follows: | | | | | | | | | | | | Weighted | | | | | | Average | | | | | | Exercise | | | Warrants | | Price | Balance at December 31, 2023 | | | 408,640 | | $ | 24.00 | Granted | | | 2,334,382 | | | 2.73 | Exercised | | | (1,275,441) | | | 3.71 | Balance at December 31, 2024 | | | 1,467,581 | | $ | 11.01 | Granted (1) | | | 7,047,040 | | | 1.06 | Exercised | | | (1,716,480) | | | 0.18 | Balance at December 31, 2025 | | | 6,798,141 | | $ | 2.36 |
| (1) | Excludes pre-funded warrants issued in connection with public offerings. |
The remaining life, by grant date, for outstanding warrants at December 31, 2025 was: | | | | | | | | | | | | | | | Remaining | | | | | | | Exercise | | Contractual | | Outstanding | | Exercisable | Grant Date | | Price | | Life in Years | | Warrants | | Warrants | May 09, 2023 | | $ | 24.00 | | 2.35 | | 303,139 | | 303,139 | April 22, 2024 | | | 6.40 | | 3.31 | | 2,377 | | 2,377 | September 25, 2025 | | | 1.35 | | 4.74 | | 1,162,065 | | 1,162,065 | September 29, 2025 | | | 1.35 | | 4.75 | | 5,330,560 | | 5,330,560 | Total | | | | | | | 6,798,141 | | 6,798,141 |
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