v3.25.4
Related-Party Transactions - Stock options (Details)
€ in Thousands
12 Months Ended
Dec. 31, 2025
EUR (€)
shares
Option
tranche
Dec. 31, 2025
Option
shares
$ / shares
Dec. 31, 2024
EUR (€)
Option
Dec. 31, 2024
$ / shares
Dec. 31, 2023
EUR (€)
Option
Dec. 31, 2023
$ / shares
Dinko Valerio, Ph.D.            
Transactions between the Company and related parties            
Number of ordinary shares outstanding | shares 725,692 725,692        
Number of options outstanding | Option 238,581 238,581        
Number of options granted | Option 22,128   23,489   22,608  
Exercise price of options granted | $ / shares   $ 2.65   $ 1.98   $ 3.41
Alison F. Lawton            
Transactions between the Company and related parties            
Number of options outstanding | Option 238,581 238,581        
Number of options granted | Option 22,138   23,489   22,608  
Exercise price of options granted | $ / shares   $ 2.65   1.98   3.41
James Shannon, M.D.            
Transactions between the Company and related parties            
Number of ordinary shares outstanding | shares 61,538 61,538        
Number of options outstanding | Option 247,661 247,661        
Number of options granted | Option 22,128   23,489   22,608  
Exercise price of options granted | $ / shares   $ 2.65   1.98   3.41
Bart Filius            
Transactions between the Company and related parties            
Number of options outstanding | Option 152,765 152,765        
Number of options granted | Option 22,128   23,489   22,608  
Exercise price of options granted | $ / shares   $ 2.65   1.98   3.41
Begoa Carreo, Ph.D.            
Transactions between the Company and related parties            
Number of options outstanding | Option 72,085 72,085        
Number of options granted | Option 22,128   23,489   22,903  
Exercise price of options granted | $ / shares   $ 2.65   1.98   3.41
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Theresa Heggie            
Transactions between the Company and related parties            
Number of ordinary shares outstanding | shares 43,623 43,623        
Number of options outstanding | shares 380,373 380,373        
Number of options granted | Option 22,128   23,489   14,418  
Exercise price of options granted | $ / shares   $ 2.65   1.98   1.74
Martin Maier, Ph.D.            
Transactions between the Company and related parties            
Number of options outstanding | Option 37,814 37,814        
Number of options granted | Option 36,314   500      
Exercise price of options granted | $ / shares       1.98    
Daniel de Boer            
Transactions between the Company and related parties            
Number of options outstanding | Option 6,274,752 6,274,752        
Number of options granted | Option 1,863,587   479,171   442,182  
Exercise price of options granted | $ / shares       1.98   3.41
Number of share options granted that are subject to non-market performance conditions | shares 1,400,000          
Bonus based on goals realized | € € 315   € 394   € 643  
Ren Beukema            
Transactions between the Company and related parties            
Number of ordinary shares outstanding | shares 460,000 460,000        
Number of options outstanding | Option 1,636,299 1,636,299        
Number of options granted 138,519   143,175   132,123  
Exercise price of options granted | $ / shares   $ 2.65   1.98   $ 3.41
Bonus based on goals realized | €     € 231   € 481  
Gerard Platenburg, Ph.D.            
Transactions between the Company and related parties            
Number of ordinary shares outstanding | shares 824,388 824,388        
Number of options outstanding | Option 1,143,502 1,143,502        
Number of options granted | Option 159,358   164,715      
Exercise price of options granted | $ / shares   $ 2.65   $ 1.98    
Bonus based on goals realized | € € 148   € 185      
Minimum | Martin Maier, Ph.D.            
Transactions between the Company and related parties            
Exercise price of options granted | $ / shares   1.9        
Minimum | Daniel de Boer            
Transactions between the Company and related parties            
Exercise price of options granted | $ / shares   2.16        
Maximum | Martin Maier, Ph.D.            
Transactions between the Company and related parties            
Exercise price of options granted | $ / shares   2.65        
Maximum | Daniel de Boer            
Transactions between the Company and related parties            
Exercise price of options granted | $ / shares   $ 2.65        
Scenario One | Dinko Valerio, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Alison F. Lawton            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | James Shannon, M.D.            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Bart Filius            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Theresa Heggie            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Martin Maier, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Daniel de Boer            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Ren Beukema            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario One | Gerard Platenburg, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 4          
Vesting percentage per tranche 25.00%          
Scenario Two | Dinko Valerio, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Alison F. Lawton            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | James Shannon, M.D.            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Bart Filius            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Theresa Heggie            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Martin Maier, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Daniel de Boer            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Ren Beukema            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%          
Scenario Two | Gerard Platenburg, Ph.D.            
Transactions between the Company and related parties            
Number of tranches 13          
Number of remaining tranches after first tranche 12          
Vesting percentage per tranche 6.25%