Equity Incentive Plans and Stock Based Compensation (Tables)
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12 Months Ended |
Dec. 31, 2023 |
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| Disclosure Of Compensation Related Costs Equity Incentives and Sharebased Payments [Abstract] |
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| Summary of Stock Option Activity Under Equity Incentive Plan |
The following table summarizes information about stock option activity for years ended December 31, 2023 and 2022:
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Weighted Average |
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Outstanding Options |
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Weighted Average |
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Remaining |
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Aggregate Intrinsic |
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Number of Shares |
|
Exercise Price |
|
Contractual Term |
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Value (in millions): |
Balances, December 31, 2021 |
|
523,411 |
|
$ |
153.11 |
|
6.72 |
|
$ |
0.95 |
Granted |
|
194,679 |
|
$ |
33.09 |
|
|
|
|
|
Exercised |
|
(3,106) |
|
$ |
10.65 |
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|
|
|
|
Cancelled |
|
(152,106) |
|
$ |
141.63 |
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|
|
|
|
Balances, December 31, 2022 |
|
562,878 |
|
$ |
115.50 |
|
7.09 |
|
$ |
— |
Granted |
|
236,651 |
|
$ |
7.25 |
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|
|
|
|
Exercised |
|
(192) |
|
$ |
7.20 |
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|
|
|
|
Cancelled |
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(285,273) |
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$ |
88.62 |
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|
|
|
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Balances, December 31, 2023 |
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514,064 |
|
$ |
80.62 |
|
7.03 |
|
$ |
— |
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Vested and expected to vest, December 31, 2023 |
|
514,064 |
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$ |
80.62 |
|
7.03 |
|
$ |
— |
Exercisable at December 31, 2023 |
|
302,935 |
|
$ |
115.92 |
|
5.67 |
|
$ |
— |
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| Stock Options Outstanding and Exercisable by Exercise Price |
As of December 31, 2023, stock options outstanding and exercisable by exercise price were as follows:
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Options Outstanding |
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Options Exercisable |
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Weighted |
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Average |
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Weighted |
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Weighted |
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Range of |
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Remaining |
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Average |
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Average |
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Exercise |
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Number |
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Contractual |
|
Exercise |
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Number |
|
Exercise |
Prices |
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Outstanding |
|
Life (Years) |
|
Price |
|
Exercisable |
|
Price |
$ |
3.73-6.32 |
|
35,149 |
|
9.79 |
|
$ |
5.61 |
|
83 |
|
$ |
4.95 |
$ |
7.20-7.20 |
|
79,708 |
|
9.11 |
|
$ |
7.20 |
|
8,705 |
|
$ |
7.20 |
$ |
7.95-10.95 |
|
62,747 |
|
9.39 |
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$ |
9.04 |
|
12,402 |
|
$ |
9.82 |
$ |
12.60-35.25 |
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34,026 |
|
3.96 |
|
$ |
18.91 |
|
29,418 |
|
$ |
18.62 |
$ |
41.55-41.55 |
|
57,562 |
|
8.12 |
|
$ |
41.55 |
|
26,305 |
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$ |
41.55 |
$ |
58.80-80.85 |
|
32,766 |
|
5.11 |
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$ |
70.30 |
|
32,555 |
|
$ |
70.28 |
$ |
94.65-94.65 |
|
57,099 |
|
4.41 |
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$ |
94.65 |
|
57,099 |
|
$ |
94.65 |
$ |
98.55-174.15 |
|
52,390 |
|
4.85 |
|
$ |
140.17 |
|
50,061 |
|
$ |
140.19 |
$ |
189.30-210.75 |
|
55,727 |
|
7.00 |
|
$ |
209.03 |
|
41,151 |
|
$ |
208.64 |
$ |
217.50-638.55 |
|
46,890 |
|
6.11 |
|
$ |
221.20 |
|
45,156 |
|
$ |
221.33 |
$ |
3.73-638.55 |
|
514,064 |
|
7.03 |
|
$ |
80.62 |
|
302,935 |
|
$ |
115.92 |
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| Stock-Based Compensation Expense |
Stock-based compensation expense, which consists of the compensation cost for employee stock options and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the consolidated statements of operations as follows (in thousands):
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Year Ended
December 31, |
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2023 |
|
2022 |
Research and development |
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$ |
2,833 |
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$ |
6,096 |
General and administrative |
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|
3,869 |
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|
5,813 |
Total stock-based compensation |
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$ |
6,702 |
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$ |
11,909 |
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| Weighted-Average Fair Value Valuation Assumptions |
The fair value of employee stock options was estimated using the following weighted-average assumptions:
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Year Ended
December 31, |
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2023 |
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2022 |
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Employee Stock Options: |
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Risk-free interest rate |
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|
4.10 |
% |
|
2.35 |
% |
Expected term (in years) |
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|
6.08 |
|
|
6.08 |
|
Dividend yield |
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|
— |
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|
— |
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Volatility |
|
|
77.72 |
% |
|
88.59 |
% |
Weighted-average fair value of stock options granted |
|
$ |
5.09 |
|
$ |
24.75 |
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