XML 53 R34.htm IDEA: XBRL DOCUMENT
v3.22.1

Term Loan - Additional Information (Details) $ / shares in Units, $ in Thousands | 1 Months Ended | 12 Months Ended
--- | --- | ---
May 31, 2021 USD ($) $ / shares shares | Apr. 30, 2020 USD ($) $ / shares shares | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Debt Instrument [Line Items] |  |  |  |
Risk free interest rate |  | 0.75% |  |
Expected volatility |  | 92.30% |  |
Expected terms (years) |  | 10 years |  |
Percentage of fee on loan |  |  | 5.00% |
Deferred tax assets |  |  | $ 42,265 | $ 22,005
Maximum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Expected terms (years) |  |  | 6 years 1 month 6 days | 6 years 1 month 6 days
Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Expected terms (years) |  |  | 5 years 6 months | 4 years
Loan Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of Credit Facility, Description | In May 2021, the parties further amended the Loan Agreement (as amended, the “2021 Loan Agreement”). The 2021 Loan Agreement increased the Term A Loan Facility to up to $20.0 million thereby increasing the total term loan facility from $15.0 million to $25.0 million. The Term B Loan Facility of up to $5.0 million remains available to be drawn upon the achievement of certain additional milestones, and each loan facility is available to be drawn upon on or before September 30, 2022. | In April 2020, the Company entered into a Loan and Security Agreement, (the “Loan Agreement”) with the lenders referred to therein (the “Lenders”), and Silicon Valley Bank (“SVB”), as collateral agent. The Loan Agreement provided for (i) a secured term A loan facility (the “Term A Loan Facility”) of up to $10.0 million and (ii) a secured term B loan facility (the “Term B Loan Facility”) of up to $5.0 million that became available upon the satisfaction of certain milestones, each of which was available to be drawn through May 31, 2021 pursuant to an amendment executed in April 2021. The term loan is secured by certain assets of the Borrowers (as defined in the Loan Agreement), including substantially all of the assets of the Company, excluding the Company’s intellectual property. The term loan contains customary representations, warranties, affirmative covenants and also certain restrictive covenants. |  |
Warrants to purchase common stock | shares | 33,923 |  |  |
Warrant exercise price | $ / shares | $ 19.12 |  |  |
Warrant expiration date | May 28, 2031 | Jun. 30, 2025 |  |
Debt issuance costs, gross | $ 600 | $ 600 |  |
Line of credit facility increase in borrowing capacity | 15,000 |  |  |
Proceeds from sale of available-for-sale securities, equity |  |  | $ 75,000 |
Deferred tax assets | 400 |  |  |
Loan Agreement | Measurement Input, Expected Dividend Payment |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fair value of warrant assumptions, dividends | $ 0 |  |  |
Loan Agreement | Valuation Technique, Option Pricing Model | Measurement Input, Risk Free Interest Rate |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fair measurement input | 0.016 |  |  |
Loan Agreement | Valuation Technique, Option Pricing Model | Measurement Input, Price Volatility |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fair measurement input | 0.986 |  |  |
Loan Agreement | Valuation Technique, Option Pricing Model | Measurement Input, Expected Term |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fair measurement input | 10 years |  |  |
Loan Agreement | Prime Rate |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 1.00% |
Loan Agreement | Maximum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | $ 25,000 |  |  |
Loan Agreement | Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, interest rate |  |  | 4.25% |
Loan Agreement | Other Assets |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt issuance costs, gross |  | 200 |  |
Loan Agreement | Term A Loan Facility |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | 20,000 | $ 10,000 |  |
Warrants to purchase common stock | shares |  | 25,000 |  |
Warrant exercise price | $ / shares |  | $ 22.06 |  |
Term loan amount drawn |  |  | $ 1,500 |
Credit facility maturity date |  |  | Sep. 01, 2024 |
Loan Agreement | Term B Loan Facility |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | $ 5,000 | $ 5,000 |  |
Warrants to purchase common stock | shares | 11,305 |  |  |

X
- Definition Fair value of warrant assumptions, dividends. + References No definition available. + Details
Name: | etnb_FairValueOfWarrantsAssumptionsDividends
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line of credit facility increase in borrowing capacity. + References No definition available. + Details
Name: | etnb_LineOfCreditFacilityIncreaseInBorrowingCapacity
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net cash proceeds from sale of equity securities. + References No definition available. + Details
Name: | etnb_NetCashProceedsFromSaleOfEquitySecurities
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of fee on loan. + References No definition available. + Details
Name: | etnb_PercentageOfFeeOnLoan
Namespace Prefix: | etnb_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The average effective interest rate during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1F -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495355-112611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of input used to measure debt instrument, including, but not limited to, convertible and non-convertible debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
Name: | us-gaap_DebtInstrumentMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399 + Details
Name: | us-gaap_DeferredFinanceCostsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
Name: | us-gaap_LineOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the credit facility terminates, in YYYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + 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)(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The risk-free interest rate assumption that is used in valuing an option on its own 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 (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + 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)(i) -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.D.2) -URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expiration date of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in YYYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=etnb_LoanAndSecurityAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedDividendPaymentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueOptionPricingModelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputRiskFreeInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedTermMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_PrimeRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=etnb_TermALoanFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=etnb_TermBLoanFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |