Stockholders' Equity (Tables)
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12 Months Ended |
Dec. 31, 2022 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Summary of Stock Option Activities |
The following table summarizes stock option activities for the year ended December 31, 2022 and 2021:
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Weighted Average |
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Remaining |
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Weighted Average |
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Contractual Life (in |
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Stock Options |
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Exercise Price |
|
years) |
Outstanding at December 31, 2020 |
|
1,141,675 |
|
$ |
5.73 |
|
6.31 |
Outstanding at December 31, 2021 |
|
1,141,675 |
|
$ |
5.73 |
|
5.31 |
Outstanding at December 31, 2022 |
|
1,141,675 |
|
|
5.73 |
|
4.31 |
Options vested and exercisable at December 31, 2022 |
|
713,547 |
|
$ |
5.73 |
|
4.31 |
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| Schedule of Stock-Based Compensation Expense |
The following table summarizes stock-based compensation expense for the years ended December 31, 2022 and 2021 (in thousands).
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For the year ended December 31, |
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2022 |
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2021 |
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General and administrative |
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$ |
700 |
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$ |
1,030 |
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Research and development |
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|
1,583 |
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|
2,278 |
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Total stock-based compensation expense |
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$ |
2,283 |
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$ |
3,308 |
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| Summary of Warrant Activities |
A summary of warrant activities for years ended December 31, 2022 and 2021, is presented below:
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Weighted Average |
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Remaining |
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Weighted Average |
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Contractual Life (in |
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Warrants |
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Exercise Price |
|
years) |
Outstanding as of December 31, 2020 |
|
5,402,670 |
|
$ |
8.21 |
|
1.39 |
Expired |
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(2,093,878) |
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|
8.50 |
|
— |
Cashless exercised |
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(138) |
|
|
— |
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— |
Outstanding as of December 31, 2021 |
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3,308,654 |
|
$ |
8.02 |
|
0.73 |
Expired |
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(3,003,770) |
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|
8.50 |
|
— |
Granted |
|
748,036 |
|
|
0.80 |
|
9.18 |
Outstanding as of December 31, 2022 |
|
1,052,920 |
|
$ |
1.52 |
|
8.29 |
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| Restricted Stock Awards [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Schedules of Restricted Stock and Restricted Stock Unit Activity |
Certain employees and directors have been awarded restricted stock. The restricted stock vesting consists of milestone and time-based vesting. The following table summarizes restricted stock award activities for the year ended December 31, 2022 and 2021:
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Weighted Average |
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Grant Date Fair |
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Number of Shares |
|
Value |
Nonvested at December 31, 2020 |
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302,114 |
|
$ |
4.93 |
Granted |
|
68,870 |
|
|
3.63 |
Vested |
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(90,001) |
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|
6.69 |
Nonvested at December 31, 2021 |
|
280,983 |
|
$ |
4.05 |
Granted |
|
358,320 |
|
|
0.70 |
Vested |
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(129,058) |
|
|
4.89 |
Nonvested at December 31, 2022 |
|
510,245 |
|
$ |
1.48 |
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| Restricted Stock Units [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Schedules of Restricted Stock and Restricted Stock Unit Activity |
The following table summarizes restricted stock units’ activities for the year ended December 31, 2022 and 2020:
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Weighted Average |
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Grant Date Fair |
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Number of Units |
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Value |
Nonvested at December 31, 2020 |
|
1,468,559 |
|
$ |
3.87 |
Granted |
|
1,660,250 |
|
|
3.07 |
Forfeited |
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(372,873) |
|
|
3.60 |
Vested |
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(420,379) |
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|
4.27 |
Nonvested at December 31, 2021 |
|
2,335,557 |
|
$ |
3.27 |
Granted |
|
1,484,647 |
|
|
0.76 |
Forfeited |
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(514,999) |
|
|
2.53 |
Vested |
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(816,518) |
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|
2.98 |
Nonvested at December 31, 2022 |
|
2,488,687 |
|
$ |
1.84 |
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