XML 50 R33.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Equity Incentive Plans (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2021
Share-based Payment Arrangement [Abstract] |
Schedule of Stock Option Activity | The following table summarizes activity under the 2008 Plan and the 2014 Plan, including grants issued to nonemployees, in the year ended December 31, 2021:
| Shares Available for Grant |  | Options Issued and Outstanding |  | Weighted Average Remaining Contractual Term |  | Aggregate Intrinsic Value
| Number of Shares |  | Weighted-Average Exercise Price per Share |  |
|  |  |  |  |  |  | (in Years) |  | (in thousands)
Balance at December 31, 2020 | 1,757,058 |  |  | 9,790,049 |  |  | $ | 6.76 |  |  |  |  |
Options authorized | 4,201,766 |  |  | — |  |  | $ | — |  |  |  |  |
Options granted | (3,409,719) |  |  | 3,409,719 |  |  | $ | 6.60 |  |  |  |  |
Options exercised | — |  |  | (331,310) |  |  | $ | 1.96 |  |  |  |  |
Options canceled | 2,451,306 |  |  | (2,451,306) |  |  | $ | 6.17 |  |  |  |  |
Issuance of common stock for services | (25,989) |  |  | — |  |  | — |  |  |  |  |
Balance at December 31, 2021 | 4,974,422 |  |  | 10,417,152 |  |  | $ | 7.00 |  |  | 6.57 |  | $ | — |
Vested and expected to vest at December 31, 2021 |  |  | 10,417,152 |  |  | $ | 7.00 |  |  | 6.57 |  | $ | — |
Exercisable at December 31, 2021 |  |  | 6,772,289 |  |  | $ | 7.39 |  |  | 5.58 |  | $ | — |
Schedule of Valuation Assumptions for Stock Options | The estimated grant date fair value of employee stock options was calculated using the Black-Scholes option-pricing model, based on the following weighted-average assumptions:
| Year Ended December 31,
| 2021 |  | 2020 |  | 2019
Expected term (years) | 4.97 |  | 6.00 |  | 6.00
Expected volatility | 77 | % |  | 83 | % |  | 81 | %
Risk-free interest rate | 4.69 | % |  | 1.07 | % |  | 2.42 | %
Dividend yield | — | % |  | — | % |  | — | %
Schedule of Restricted Stock Units Activity | The following table summarizes restricted stock unit activity under the 2014 Plan in the year ended December 31, 2021, and includes restricted stock units with time or service-based vesting and those restricted stock units with performance-based vesting:
| Number of RSUs |  | Weighted-Average Grant Date Fair Value Per Share |  |  |  |
Non-vested restricted stock units at December 31, 2020 | 158,626 |  |  | $ | 5.64 |  |  |  |  |
Granted | 4,144,051 |  |  | $ | 2.71 |  |  |  |  |
Vested | (193,147) |  |  | $ | 6.39 |  |  |  |  |
Forfeited | (580,848) |  |  | $ | 6.38 |  |  |  |  |
Non-vested restricted stock units at December 31, 2021 | 3,528,682 |  |  | $ | 2.04 |  |  |  |  |
Schedule of Employee Stock Purchase Plan Activity | The following table summarizes our ESPP activity during the year ended December 31, 2021:
| Shares Available for Grant |  | Number of Shares Purchased |  | Average Purchase Price per Share |  | Gross Proceeds
|  |  |  |  |  |  | (in thousands)
Balance at December 31, 2020 | 349,647 |  |  | 661,611 |  |  |  |  |
Shares purchased | (386,664) |  |  | 386,664 |  |  | $ | 2.12 |  |  | $ | 819 |
Balance at December 31, 2021 | 898,982 |  |  | 1,048,275 |  |  |  |  |
Schedule of Valuation Assumptions for Employee Stock Purchase Plan | The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of ESPP purchase rights granted to our employees:
| Year Ended December 31,
| 2021 |  | 2020 |  | 2019
Expected term (years) | 0.50 |  | 0.50 |  | 0.50
Expected volatility | 123 | % |  | 79 | % |  | 69 | %
Risk-free interest rate | 0.65 | % |  | 0.48 | % |  | 2.00 | %
Dividend yield | — | % |  | — | % |  | — | %
Schedule of Stock-Based Compensation Recognized | Total stock-based compensation recognized was as follows (in thousands):
| Year Ended December 31,
| 2021 |  | 2020 |  | 2019
Research and development | $ | 4,116 |  |  | $ | 4,061 |  |  | $ | 4,104 |
General and administrative | 7,923 |  |  | 6,522 |  |  | 5,832 |
Total | $ | 12,039 |  |  | $ | 10,583 |  |  | $ | 9,936 |
Schedule of Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures | At December 31, 2021, the Company had total unrecognized stock-based compensation expense, net of estimated forfeitures, of the following (dollars in thousands):
| December 31, 2021
| Unrecognized Compensation Expense |  | Average Remaining Vesting Period (Years)
Stock options grant | $ | 14,506 |  |  | 2.4
RSU grants | $ | 2,262 |  |  | 0.8
ESPP | $ | 44 |  |  | 0.1

X
- References No definition available. + Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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 employee stock purchase plan activity. + 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 (g) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock
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 employee stock purchase plans, including, but not limited to: (a) expected term, (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_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock
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
- Definition Tabular disclosure of cost not yet recognized and weighted-average period over which cost is expected to be recognized for nonvested award under share-based payment arrangement. + 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 (i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfUnrecognizedCompensationCostNonvestedAwardsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration