XML 60 R24.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Stock-Based Compensation (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2021
Summary of Option Plans | Stock Options Stock option activity under the Options Plan is set forth below for the year ended December 31, 2021:
|  | Number of Shares Outstanding |  |  | Weighted Average Exercise Price Per Share |  |  | Weighted Average Remaining Contractual Term (Years) |  |  | Aggregate Intrinsic Value (in thousands) |
Balances at December 31, 2020 |  |  | 1,481,100 |  |  | $ | 16.13 |  |  |  | 8.36 |  |  | $ | 11,123 |
Stock options granted |  |  | 794,095 |  |  |  | 21.62 |  |  |  |  |  |  |  |  |
Stock options exercised |  |  | (120,178 | ) |  |  | 9.88 |  |  |  |  |  |  |  |  |
Stock options forfeited |  |  | (130,336 | ) |  |  | 21.30 |  |  |  |  |  |  |  |  |
Balances at December 31, 2021 |  |  | 2,024,681 |  |  | $ | 18.33 |  |  |  | 8.04 |  |  | $ | 38,417 |
Vested and expected to vest at December 31, 2021 |  |  | 2,024,681 |  |  | $ | 18.33 |  |  |  | 8.04 |  |  | $ | 38,417 |
Exercisable at December 31, 2021 |  |  | 1,028,650 |  |  | $ | 14.75 |  |  |  | 7.41 |  |  | $ | 23,142 |
Summary of RSU Activity | Restricted Stock Units (“RSU”) activity under the 2019 Plan is set forth below for the year ended December 31, 2021:
|  | Number of Shares Outstanding |  |  | Weighted Average Grant Price Fair Value Per Share |
RSUs outstanding at December 31, 2020 |  |  | 56,500 |  |  |  | 44.66 |
RSUs awarded |  |  | — |  |  |  | — |
RSUs released |  |  | (14,125 | ) |  |  | 44.66 |
RSUs forfeited |  |  | (1,875 | ) |  |  | 44.66 |
RSUs outstanding at December 31, 2021 |  |  | 40,500 |  |  |  | 44.66 |
Summary of Assumptions Used to Value Under Stock Option Plans | The fair value of the rights granted to employees under the 2019 ESPP was estimated using a Black-Scholes option-pricing model with the following valuation assumptions:
|  | Year Ended December 31, |
|  | 2021 |  | 2020 |
Expected term (in years) |  | 0.25 - 2.00 |  | 0.25 - 2.00 |
Volatility |  | 71.3% - 92.9% |  | 84.0% |
Risk-free interest rate |  | 0.05% - 1.55% |  | 0.11% - 1.57% |
Dividend yield |  | — |  | — |
Summary of Stock-based Compensation Expense | Total stock-based compensation expense recognized for stock options and RSUs granted to both employees and non-employees and for the employee stock purchase plan was as follows (in thousands):
|  | Year Ended December 31, |
|  | 2021 |  |  | 2020 |
Research and development |  | $ | 5,310 |  |  | $ | 4,637 |
General and administrative |  |  | 4,642 |  |  |  | 4,049 |
Total stock-based compensation expense |  | $ | 9,952 |  |  | $ | 8,686 |
Employee and Non-employees |
Summary of Assumptions Used to Value Under Stock Option Plans | The assumptions used to value employee and non-employee stock option awards granted under the Option Plans during the years ended December 31, 2021 and 2020, using the Black-Scholes option pricing model, were as follows:
|  | Year Ended December 31,
|  | 2021 |  | 2020
Expected term (in years) |  | 3.93 - 6.05 |  | 5.19 - 6.07
Volatility |  | 81.0% - 86.9% |  | 84.0% - 87.0%
Risk-free interest rate |  | 0.55% - 1.26% |  | 0.28% - 1.43%
Dividend yield |  | — |  | —

X
- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 + Details
Name: | us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_GranteeStatusAxis=us-gaap_ShareBasedPaymentArrangementEmployeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |