Note 8 - Stockholders' Equity	3 Months Ended
Mar. 31, 2022
Notes to Financial Statements
Preferred Stock [Text Block]	8. Stockholders’ Equity Private Placement – On January 19, 2022, we closed a private placement of 707,484 shares of common stock, a pre-funded warrant to purchase 2,360,000 shares of common stock (the “Pre-Funded Warrant”), and a warrant to purchase up to 3,067,484 shares of common stock at an exercise price of $3.26 per share (the “Common Warrant”). Net proceeds after deducting placement agent commissions and other offering expenses were approximately $9.2 million. During March 2022, the Pre-Funded Warrant was exercised in full, for nominal net proceeds. The Common Warrant is currently exercisable and will expire on February 10, 2027. Stock Options – We have a stock-based incentive plan (the “2020 Plan”) pursuant to which our Board of Directors may grant stock options and other stock-based awards to our employees, directors and consultants. A total of 1,500,000 shares of our common stock are reserved for issuance pursuant to the 2020 Plan. During the three months ended March 31, 2022, there were no stock option transactions related to the 2020 Plan. As of March 31, 2022, there are 962,300 stock options outstanding, with a weighted-average exercise price of $3.18 per share and a weighted-average remaining term of 9.1 years. Stock Purchase Warrants – As of March 31, 2022, there are 5,884,115 stock purchase warrants outstanding with a weighted-average exercise price of $4.23 per share and a weighted-average remaining term of 4.2 years.

Note 8 - Stockholders' Equity

3 Months Ended

Mar. 31, 2022

8. Stockholders’ Equity

Private Placement – On January 19, 2022, we closed a private placement of 707,484 shares of common stock, a pre-funded warrant to purchase 2,360,000 shares of common stock (the “Pre-Funded Warrant”), and a warrant to purchase up to 3,067,484 shares of common stock at an exercise price of $3.26 per share (the “Common Warrant”). Net proceeds after deducting placement agent commissions and other offering expenses were approximately $9.2 million. During March 2022, the Pre-Funded Warrant was exercised in full, for nominal net proceeds. The Common Warrant is currently exercisable and will expire on February 10, 2027.

Stock Options – We have a stock-based incentive plan (the “2020 Plan”) pursuant to which our Board of Directors may grant stock options and other stock-based awards to our employees, directors and consultants. A total of 1,500,000 shares of our common stock are reserved for issuance pursuant to the 2020 Plan. During the three months ended March 31, 2022, there were no stock option transactions related to the 2020 Plan. As of March 31, 2022, there are 962,300 stock options outstanding, with a weighted-average exercise price of $3.18 per share and a weighted-average remaining term of 9.1 years.

Stock Purchase Warrants – As of March 31, 2022, there are 5,884,115 stock purchase warrants outstanding with a weighted-average exercise price of $4.23 per share and a weighted-average remaining term of 4.2 years.