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Commitments and Contingencies (Details Textual) € in Millions |  | 1 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Aug. 29, 2020 ft² | Jul. 31, 2021 EUR (€) | Jun. 30, 2021 ft² | Sep. 30, 2023 USD ($) | Sep. 30, 2022 USD ($) | Dec. 31, 2022 USD ($) Employee
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Workforce reduction, percentage |  |  |  |  |  | 67.00%
Workforce reduction, number of employees | Employee |  |  |  |  |  | 12
Severance expense |  |  |  | $ 159,000 |  |
Area of office facilities taken on lease | ft² | 5,200 |  |  |  |  |
Operating lease term | 42 months |  |  |  |  |
Additional operating lease term | 36 months |  |  |  |  |
Lease renewal option |  |  |  | option to renew for an additional 36 month term at the then prevailing rental rate. |  |
Lessee, Operating Lease, Existence of Option to Extend [true false] | true |  |  |  |  |
Area of additional office facilities taken on sublease | ft² |  |  | 3,000 |  |  |
Operating sublease term |  |  | 29 months |  |  |
Lessee, Operating Sublease, Existence of Option to Extend [true false] |  |  | false |  |  |
Lessee, operating lease, assumptions and judgments, allocation of lease and nonlease component |  |  |  | The leases include real estate taxes and insurance, which is not a lease component and is not included in the lease obligation. In addition, common area maintenance charges are based on actual costs incurred and are a non-lease component that is not included in the lease obligation. |  |
Operating lease, cash paid for measurement of lease liabilities |  |  |  | $ 101,000 | $ 98,000 |
Lease liability |  |  |  | $ 301,000 |  |
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] |  |  |  | Accrued expenses and other liabilities |  |
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] |  |  |  | Operating lease liability, net of current portion |  |
Weighted-average remaining lease term |  |  |  | 3 years 4 months 24 days |  |
Weighted-average discount rate |  |  |  | 7.00% |  |
One-time Termination Benefits |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Restructuring charges |  |  |  |  |  | $ 755,000
General and Administrative Expense |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Rent expense |  |  |  | $ 94,000 | $ 94,000 |
General and Administrative Expense | One-time Termination Benefits |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Restructuring charges |  |  |  |  |  | 285,000
Accrued Compensation And Employee Benefits |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Restructuring Reserve, Current |  |  |  | $ 12,000 |  |
Research and development | Patent Assignment Agreement | University Medical Center of Johannes Gutenberg University Mainz |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Potential upfront and milestone obligations and royalty obligations | € |  | € 1.6 |  |  |  |
Research and development | One-time Termination Benefits |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Restructuring charges |  |  |  |  |  | 470,000
Clinical development decisions |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |
Amount of retention bonuses |  |  |  |  |  | $ 265,000

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