v3.26.1
Segment Reporting - Summary of Segment Loss Including Significant Segment Expenses (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Research and development expenses:    
Segment loss and net loss $ 161,307 $ 127,477
Operating Segment    
Research and development expenses:    
Other research and development expenses 54,421 46,642
General and administrative expenses 36,107 30,131
Interest income (9,094) (15,359)
Interest expense and other expense, net 574 232
Segment loss and net loss 161,307 127,477
Operating Segment | KYV-101    
Research and development expenses:    
External research and development expenses allocated by program 76,054 61,884
Operating Segment | Other Programs    
Research and development expenses:    
External research and development expenses allocated by program $ 3,245 $ 3,947