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Debt - Additional Information (Details) |  |  |  |  |  |  | 3 Months Ended | 9 Months Ended | 48 Months Ended |  |
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May 13, 2025 | Jan. 31, 2025 USD ($) | Oct. 28, 2024 | Sep. 08, 2020 USD ($) Debtinstrument | Jan. 21, 2020 USD ($) Debtinstrument | Nov. 18, 2015 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Jan. 31, 2025 USD ($) shares | Apr. 28, 2025 $ / shares | Apr. 27, 2018 USD ($) $ / shares shares
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase preferred shares, exercise price | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 0.01 |
Accretion of debt discounts and deferred financing costs |  |  |  |  |  |  |  |  | $ 194,000 | $ 1,713,000 |  |  |
Aggregate principal amount of exchangeable notes |  |  |  |  |  |  |  |  |  |  | $ 40,691,000 |  |
Accrued and unpaid interest |  |  |  |  |  |  |  |  |  |  | $ 3,071,000 |  |
Issuance of ordinary shares on conversion of exchangeable notes (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 3,760,155 |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  |  | $ 40,691,000 |  |
Pfizer License Agreement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory milestone payments upon approval of product |  |  |  |  |  | $ 20,000,000 |  |  |  |  |  |  |
Regulatory and sales milestone deferred payment annual rate |  |  |  |  |  | 8.00% |  |  |  |  |  |  |
Regulatory and sales milestone deferred payment period |  |  | 2 years |  |  |  |  |  |  |  |  |  |
A&R Note and Letter Agreement | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory and sales milestone deferred payment annual rate | 10.00% |  |  |  |  |  |  |  |  |  |  |  |
A&R Note and Letter Agreement | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory and sales milestone deferred payment annual rate | 8.00% |  |  |  |  |  |  |  |  |  |  |  |
Debt modification percent | 10.00% |  |  |  |  |  |  |  |  |  |  |  |
Exchangeable Notes |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount of exchangeable notes |  | $ 11,117,000 |  |  |  |  |  |  |  |  | 40,691,000 |  |
Accrued and unpaid interest |  |  |  |  |  |  |  |  |  |  | 3,071,000 |  |
Aggregate principal amount |  | 11,117,000 |  |  |  |  |  |  |  |  | 40,691,000 |  |
Accrued interest |  | $ 3,628,000 |  |  |  |  |  |  |  |  | 3,628,000 |  |
Exchangeable Notes | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount of exchangeable notes |  |  |  |  |  |  |  |  |  |  | 40,691,000 |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  |  | $ 40,691,000 |  |
Promissory Note |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  | $ 562,000 |  | $ 1,415,000 |  |  |  |
Loan and Security Agreement | Silicon Valley Bank (SVB) |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Loan and security agreement entered date |  |  |  |  |  |  |  |  | Apr. 27, 2018 |  |  |  |
Funded amount under agreement |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000,000
Maximum amount available under agreement |  |  |  |  |  |  |  |  |  |  |  |  | $ 30,000,000
Silicon Valley Bank and Life Sciences Fund II LLC | Ordinary Shares |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of warrants to purchase ordinary shares | shares |  |  |  |  |  |  |  |  |  |  |  |  | 1,326
Silicon Valley Bank and Life Sciences Fund II LLC | Series B Convertible Preferred Shares |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of warrants to purchase ordinary shares | shares |  |  |  |  |  |  |  |  |  |  |  |  | 19,890
Warrants to purchase preferred shares, exercise price | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  | $ 282.75
2025 Exchangeable Notes |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  | 0 | $ 181,000 | $ 88,000 | 542,000 |  |  |
Accretion of debt discounts and deferred financing costs |  |  |  |  |  |  | $ 0 | $ 575,000 | $ 194,000 | $ 1,713,000 |  |  |
2025 Exchangeable Notes | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  | $ 51,588,000 |  |  |  |  |  |  |  |
Debt instrument price per unit |  |  |  |  | $ 1,000 |  |  |  |  |  |  |  |
2025 Exchangeable Notes | Private Placement and Rights Offering |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | $ 51,808,000 |  |  |  |  |  |  |  |  |
Debt instrument interest rate |  |  |  |  | 6.50% |  |  |  |  |  |  |  |
2025 Exchangeable Notes | Rights Offering |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | 220,000 |  |  |  |  |  |  |  |  |
2020 Rights Offering | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument price per unit |  |  |  | 1,000 |  |  |  |  |  |  |  |  |
2020 Rights Offering | Rights Offering |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | $ 220,000 |  |  |  |  |  |  |  |  |
RLNs | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  | $ 103,000 |  |  |  |  |  |  |  |
Number of debt instruments within each notes | Debtinstrument |  |  |  | 50 | 50 |  |  |  |  |  |  |  |
RLNs | Private Placement and Rights Offering |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | $ 500 | $ 104,000 |  |  |  |  |  |  |  |
RLNs | Rights Offering |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | 440 |  |  |  |  |  |  |  |  |
Securities | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument price per unit |  |  |  | $ 1,000 | $ 1,000 |  |  |  |  |  |  |  |

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