XML 46 R27.htm IDEA: XBRL DOCUMENT
v3.19.1

Stock-Based Compensation (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |
Summary of Stock-Based Compensation Expense | Total stock-based compensation expense is recognized for stock options granted to employees and non-employees and has been reported in the Company’s condensed consolidated condensed statements of operations as follows:
|  | Three Months Ended March 31, |
|  | 2019 |  |  | 2018 |
Research and development |  | $ | 277 |  |  | $ | 625 |
General and administrative |  |  | 386 |  |  |  | 556 |
Total stock-based compensation expense |  | $ | 663 |  |  | $ | 1,181 |
Summary of Stock Option Activity | The following table summarizes stock option activity under the Plans:
|  | Shares Available for Grant |  |  | Number of Options Outstanding |  |  | Weighted- Average Exercise Price per Option |  |  | Weighted- Average Remaining Contract Term |  |  | Aggregate Intrinsic Value |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (In thousands) |
Outstanding, December 31, 2018 |  |  | 1,350,582 |  |  |  | 1,122,677 |  |  | $ | 11.63 |  |  |  | 9.22 |  |  |  |  |
Shares reserved for issuance |  |  | 1,122,213 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Options granted(1) |  |  | (604,440 | ) |  |  | 604,440 |  |  |  | 8.58 |  |  |  |  |  |  |  |  |
Options cancelled |  |  | 20,800 |  |  |  | (20,800 | ) |  |  | 9.91 |  |  |  |  |  |  |  |  |
Outstanding, March 31, 2019 |  |  | 1,889,155 |  |  |  | 1,706,317 |  |  |  | 10.57 |  |  |  | 9.30 |  |  | $ | 627 |
Exercisable, March 31, 2019 |  |  |  |  |  |  | 194,221 |  |  |  | 11.62 |  |  |  | 8.70 |  |  |  | 202 |
Vested and expected to vest, March 31, 2019 |  |  |  |  |  |  | 1,706,317 |  |  |  | 10.57 |  |  |  | 9.30 |  |  |  | 627 |
(1) | The Company granted 9,840 stock options to non-employees during the three months ended March 31, 2019.
Schedule of Assumptions to Estimate Fair Value of Stock Options for Employees and Non-Employees Using Black-Scholes Option Pricing Model | The fair value of stock options for employees and non-employees was estimated using a Black-Scholes option pricing model with the following assumptions:
|  | Three Months Ended March 31,
|  | 2019 |  |  | 2018
Employees: |  |  |  |  |  |
Fair value of common stock |  | $8.53 - $8.90 |  |  | $13.17 - $15.45
Expected term (in years) |  |  | 6.1 |  |  | 5.8 - 6.6
Expected volatility |  | 93.7% - 94.8% |  |  | 76.1% - 77.7%
Risk-free interest rate |  | 2.5% - 2.6% |  |  | 2.4% - 2.7%
Expected dividend yield |  | 0.0% |  |  | 0.0%
Non-employees: |  |  |  |  |  |
Fair value of common stock |  | $6.82 - $8.61 |  |  | $9.58 - $15.45
Expected term (in years) |  | 8.2 - 10.0 |  |  | 9.2 - 10.0
Expected volatility |  | 91.3% - 94.9% |  |  | 77.9% - 78.1%
Risk-free interest rate |  | 2.4% - 2.6% |  |  | 2.7% - 2.8%
Expected dividend yield |  | 0.0% |  |  | 0.0%
Summary of Restricted Stock Activity | The summary of restricted stock activity and related information follows:
|  | Number of Restricted Shares Outstanding |
Unvested shares — December 31, 2018 |  |  | 1,000 |
Vested |  |  | (500 | )
Unvested shares — March 31, 2019 |  |  | 500 |
Summary of Restricted Stock Units Activity | The summary of restricted stock unit activity and related information follows:
|  | Number of Restricted Stock Units Outstanding |
Unvested shares — December 31, 2018 |  |  | 24,960 |
Granted |  |  | — |
Vested |  |  | — |
Unvested shares — March 31, 2019 |  |  | 24,960 |

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 the changes in outstanding nonvested restricted stock shares. + 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) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_NonvestedRestrictedStockSharesActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the amount of total share-based compensation cost, including the amounts attributable to each share-based compensation plan and any related tax benefits. + 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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the changes in outstanding nonvested restricted stock units. + 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)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum: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=109197908&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=109197908&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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum: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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration