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%
|
|