v3.26.1
Note 10 - Stock-based Compensation (Tables)
12 Months Ended
Dec. 31, 2025
Notes Tables  
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]
    Year Ended December 31,  
   

2025

   

2024

 

Research and development

  $ 246     $ 375  

Selling, general and administrative

    453       614  

Total

  $ 699     $ 989  
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]
           

Weighted

 
   

Number of

   

Average

 
   

Restricted

   

Grant Date

 
   

Stock Units

   

Fair Value

 

Restricted stock units outstanding, January 1, 2024

    86,232     $ 7.57  

Granted

    176,768       1.03  

Vested

    (42,525 )     11.31  

Forfeited

    (7,552 )     2.03  

Restricted stock units outstanding, December 31, 2024

    212,923     $ 1.59  

Granted

    158,966       0.69  

Vested

    (93,606 )     2.18  

Forfeited

    (5,088 )     0.80  

Restricted stock units outstanding, December 31, 2025

    273,195     $ 0.88  
Share-Based Payment Arrangement, Option, Activity [Table Text Block]
   

Number
of Stock Options
Outstanding

   

Weighted-
Average
Exercise
Price

   

Weighted-
Average
Remaining
Contractual
Life (Years)

   

Aggregate
Intrinsic
Value

 
                           

(in thousands)

 

January 1, 2024

    893,321     $ 33.41                  

Granted

    1,053,612       1.03                  

Forfeited

    (41,156 )     1.75                  

Expired

    (118,877 )     71.96                  

January 1, 2025

    1,786,900     $ 12.48                  

Granted

    919,781       0.70                  

Exercised

    (14,000 )     1.03                  

Forfeited

    (32,561 )     0.93                  

Expired

    (49,643 )     49.11                  

December 31, 2025

    2,610,477     $ 7.84       7.6     $ 519  
                                 

Vested and exercisable options—December 31, 2025

    1,122,077     $ 17.06       6.0     $ 72  

Vested and expected to vest—December 31, 2025

    2,610,477     $ 7.84       7.6     $ 519  
Schedule of Share-based Compensation, Stock Options Outstanding and Exercisable Activity [Table Text Block]
   

Options Outstanding

   

Options Vested and Exercisable

 

Exercise Prices

 

Number of
Stock Options
Outstanding

   

Weighted-Average
Remaining
Contractual Life
(Years)

   

Weighted-Average
Exercise Price per
Share

   

Shares Subject
to Stock
Options

   

Weighted-Average
Exercise Price per
Share

 

$0.58 - $0.89

    812,073       9.1     $ 0.62       102,673     $ 0.84  

$0.91 - $1.37

    1,104,289       8.5     $ 1.06       399,937     $ 1.04  

$1.76 - $2.64

    244,272       7.1     $ 1.76       173,021     $ 1.76  

$4.62 - $6.93

    10,850       6.5     $ 4.62       10,850     $ 4.62  

$8.03 - $12.05

    82,079       6.1     $ 8.07       78,682     $ 8.07  

$14.40 - $21.60

    9,083       4.3     $ 16.40       9,083     $ 16.40  

$22.40 - $33.60

    11,700       5.1     $ 28.62       11,700     $ 28.62  

$34,40 - $51.60

    192,319       3.1     $ 41.80       192,319     $ 41.80  

$57.40 - $86.10

    143,812       0.9     $ 63.48       143,812     $ 63.48  
      2,610,477       7.6     $ 7.84       1,122,077     $ 17.06  
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
 

Year Ended December 31, 

 

2025

 

2024

Expected term (in years)         

6.7

 

6.5

Risk-free interest rate         

3.8% - 4.0%

 

4.1% - 4.5%

Expected volatility         

95%

 

98%

Expected dividend rate         

0%

 

0%