Segment reporting - Schedule of segment reporting (Details) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Jun. 30, 2026
USD ($)
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Jun. 30, 2025
USD ($)
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Jun. 30, 2026
USD ($)
segment
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Jun. 30, 2025
USD ($)
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| Segment reporting | ||||
| Number of operating segments | segment | 1 | |||
| Number of reportable segments | segment | 1 | |||
| Loss from operations | $ (52,203) | $ (43,865) | $ (97,923) | $ (83,196) |
| Depreciation and amortization expense | (7,863) | (8,157) | ||
| Fair value (loss) / gain - contingent consideration | 82 | (3,470) | ||
| Fair value loss - Liability related to pre-funded warrants | 12,201 | |||
| Foreign currency (losses) / gains, net | (1,730) | 18,638 | (4,024) | 25,810 |
| Interest income | 5,051 | 3,524 | 10,280 | 7,651 |
| Interest expense - Royalty Financing Agreement | (17,384) | (20,626) | ||
| Other reconciling items | (15,970) | (12,201) | ||
| Loss before income tax expense | (79,218) | (37,294) | (132,265) | (80,435) |
| Operating Segment | Single Reportable Segment | ||||
| Segment reporting | ||||
| Revenue | 5,841 | 5,262 | 9,403 | 6,829 |
| Employee related expenses | (16,960) | (14,525) | (33,746) | (28,741) |
| Laboratory and development expenses | (17,387) | (15,593) | (32,148) | (31,560) |
| Professional fees | (1,756) | (3,124) | (6,263) | (5,181) |
| Information technology system costs | (1,427) | (838) | (3,086) | (1,839) |
| Facility expenses | (1,437) | (1,704) | (2,984) | (3,371) |
| Other segment items(1) | (2,511) | (1,804) | (6,024) | (2,773) |
| Loss from operations | $ (35,637) | $ (32,326) | $ (74,848) | $ (66,636) |
| Other segment items description | (1) Other segment items included in segment operating loss include costs related to intellectual property and insurance offset by income related to payments received from European authorities to subsidize the Company's research and development in the Netherlands. (2) The comparative amounts for the three and six months ended June 30, 2025 have been adjusted to reflect the level of detail at which the CODM reviews segment operating expenses in 2026, with information technology system costs presented as a separate line item and consumables included within other segment items for all periods presented. | (1) Other segment items included in segment operating loss include costs related to intellectual property and insurance offset by income related to payments received from European authorities to subsidize the Company's research and development in the Netherlands. (2) The comparative amounts for the three and six months ended June 30, 2025 have been adjusted to reflect the level of detail at which the CODM reviews segment operating expenses in 2026, with information technology system costs presented as a separate line item and consumables included within other segment items for all periods presented. | (1) Other segment items included in segment operating loss include costs related to intellectual property and insurance offset by income related to payments received from European authorities to subsidize the Company's research and development in the Netherlands. (2) The comparative amounts for the three and six months ended June 30, 2025 have been adjusted to reflect the level of detail at which the CODM reviews segment operating expenses in 2026, with information technology system costs presented as a separate line item and consumables included within other segment items for all periods presented. | (1) Other segment items included in segment operating loss include costs related to intellectual property and insurance offset by income related to payments received from European authorities to subsidize the Company's research and development in the Netherlands. (2) The comparative amounts for the three and six months ended June 30, 2025 have been adjusted to reflect the level of detail at which the CODM reviews segment operating expenses in 2026, with information technology system costs presented as a separate line item and consumables included within other segment items for all periods presented. |
| Material Reconciling | Single Reportable Segment | ||||
| Segment reporting | ||||
| Depreciation and amortization expense | $ (4,907) | $ (3,630) | $ (7,863) | $ (8,157) |
| Share-based compensation expense | (5,016) | (5,084) | (10,106) | (9,494) |
| Fair value (loss) / gain - contingent consideration | (1,256) | (2,254) | 82 | (3,470) |
| Fair value loss - Liability related to pre-funded warrants | (15,970) | (12,201) | ||
| Foreign currency (losses) / gains, net | (1,730) | 18,638 | (4,024) | 25,810 |
| Interest income | 5,051 | 3,524 | 10,280 | 7,651 |
| Interest expense - Royalty Financing Agreement | (12,963) | (13,770) | (25,584) | (27,079) |
| Interest expense - Hercules debt facility | (1,403) | (1,821) | (2,813) | (3,621) |
| Other reconciling items | $ (5,387) | $ (571) | $ (5,188) | $ 4,561 |
| X | ||||||||||
- Definition Amount of facility expenses. No definition available.
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- Definition Represents the expense for laboratory and development expense. No definition available.
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- Definition The amount of interest expense net of interest paid on royalty financing agreement. No definition available.
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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of increase (decrease) in value of liability in contingent consideration arrangement in business combination, including, but not limited to, difference arising upon settlement. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The amount of expense in the period for communications and data processing expense. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of expense (income) related to adjustment to fair value of warrant liability. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount, before tax, of realized and unrealized gain (loss) from foreign currency transaction. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition The net result for the period of deducting operating expenses from operating revenues. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of income (expense) related to nonoperating activities, classified as other. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of other expense (income) and loss (gain) calculated as difference between segment revenue and separately disclosed expense category to arrive at segment profit (loss). Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Description of composition of other segment item not separately disclosed. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- 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. No definition available.
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