v3.26.3
Notes to the unaudited interim condensed consolidated statement of financial position - Shareholders' equity - Changes in share capital (Details) - EUR (€)
 6 Months Ended
Jun. 05, 2026
Jun. 02, 2026
Apr. 23, 2026
Feb. 11, 2026
Jan. 23, 2026
Jan. 14, 2026
Jan. 01, 2026
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Disclosure of classes of share capital [line items]                      
Shareholders' equity               € 59,002,000 € (8,909,000) € (28,522,000) € (106,647,000)
Issue of equity               103,197,000 [1] 135,550,000 [2]    
Increase (decrease) through share-based payment transactions, equity               11,753,000 8,009,000    
Transaction costs               € 8,205,000 € 7,519,000    
Number of shares outstanding               236,280,202   193,236,978  
Nominal value               € 0.01      
Tranche I, 2024 Financing arrangement in three tranches | T1 bis BSA Warrants                      
Disclosure of classes of share capital [line items]                      
Number of shares           2,059,386          
Nominal value           € 0.01          
Shares issued during period upon exercise of warrants           2,059,386          
Proceeds from exercise of warrants           € 20,594          
Tranche I, 2024 Financing arrangement in three tranches | T1 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Number of shares     1,300,000 1,300,000              
Nominal value     € 0.01 € 0.01              
Shares issued during period upon exercise of warrants     1,300,000 1,300,000              
Proceeds from exercise of warrants       € 13,000              
Tranche II, 2024 Financing arrangement in three tranches | T2 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Number of shares         11,111,111            
Nominal value         € 0.01            
Shares issued during period upon exercise of warrants         11,111,111            
Proceeds from exercise of warrants         € 111,111            
Tranche II, 2024 Financing arrangement in three tranches | T2 New Share                      
Disclosure of classes of share capital [line items]                      
Number of shares issued during the period                 42,488,883    
Registered underwritten public offering                      
Disclosure of classes of share capital [line items]                      
Transaction costs             € 400,000        
Equity offering                      
Disclosure of classes of share capital [line items]                      
Transaction costs € 7,800,000           7,800,000        
Number of shares 27,272,727                    
Nominal value € 0.01                    
Number of shares issued during the period 27,272,727             27,272,727      
Equity offering | ADS                      
Disclosure of classes of share capital [line items]                      
Number of shares issued during the period   27,272,727                  
Share capital                      
Disclosure of classes of share capital [line items]                      
Shareholders' equity               € 2,362,802 € 1,392,000 € 1,932,370 € 957,000
Issue of equity               430,000 [1] € 435,000 [2]    
Exercise of warrants               € 157,000      
Number of shares outstanding               236,280,202 139,151,274 193,236,978 95,662,391
Nominal value               € 0.01   € 0.01  
Share capital | Tranche I, 2024 Financing arrangement in three tranches | T1 bis BSA Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants           € 20,594          
Nominal value           € 0.01          
Share capital | Tranche I, 2024 Financing arrangement in three tranches | T1 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants     € 13,000 € 13,000              
Nominal value     € 0.01 € 0.01              
Share capital | Tranche II, 2024 Financing arrangement in three tranches | T2 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants         € 111,111            
Nominal value         € 0.01            
Share capital | Registered underwritten public offering                      
Disclosure of classes of share capital [line items]                      
Transaction costs             428,028        
Share capital | Equity offering                      
Disclosure of classes of share capital [line items]                      
Issue of equity € 272,727             € 272,000      
Exercise of warrants € 272,727                    
Nominal value € 0.01                    
Premiums related to share capital                      
Disclosure of classes of share capital [line items]                      
Shareholders' equity               643,924,498 [3] € 376,755,000 € 528,230,262 [3] € 249,160,000
Issue of equity               123,899,000 [1],[3] 135,115,000 [2]    
Transaction costs               8,205,000 [3] € 7,519,000    
Exercise of warrants               21,100,000      
Premiums related to share capital | Tranche I, 2024 Financing arrangement in three tranches | T1 bis BSA Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants           € 2,759,577          
Premiums related to share capital | Tranche I, 2024 Financing arrangement in three tranches | T1 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants     € 1,742,000 € 1,742,000              
Premiums related to share capital | Tranche II, 2024 Financing arrangement in three tranches | T2 BSA Prefunded Warrants                      
Disclosure of classes of share capital [line items]                      
Exercise of warrants         € 14,888,889            
Premiums related to share capital | Registered underwritten public offering                      
Disclosure of classes of share capital [line items]                      
Transaction costs             € 400,000        
Premiums related to share capital | Equity offering                      
Disclosure of classes of share capital [line items]                      
Issue of equity € 94,989,798             € 102,800,000      
[1] Share capital variation include a €272 thousand increase from the Equity Offering completed on June 5, 2026, corresponding to the issuance of 27,272,727 ordinary shares, and a €157 thousand increase in share capital resulting from the exercise of T1 and T2 warrants issued under the Structured Financing (see Note 4.8 – Shareholders’ equity).
[2] Corresponding mainly to the share capital increase consisting of the issuance of 42,488,883 new ordinary shares (see Note 4.8 Shareholders’ equity to the annual consolidated financial statements for the year ended on December 31, 2025)
[3] Premiums related to share capital include €102.8 million of share premium resulting from the Equity Offering and €21.1 million resulting from the exercise of T1 and T2 warrants issued under the Structured Financing and (€7.8) million of transaction costs related to the Equity Offering and (€0.4) million relating to transaction costs recognized on January 1, 2026 in connection with the November 2025 public offering (see Note 4.8 – Shareholders’ equity).