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License, Clinical Trial and Sponsored Research Agreements (Other - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)

v3.24.4
License, Clinical Trial and Sponsored Research Agreements (Other - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 08, 2021
Jul. 03, 2017
Oct. 31, 2022
Jan. 31, 2022
Jun. 30, 2021
Nov. 30, 2020
Jun. 30, 2020
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Dec. 31, 2022
License, Clinical Trial and Sponsored Research Agreements                          
Research and development expense               $ 57 $ 9,527 $ 8,221 $ 34,363 $ 40,513 $ 62,475
Sponsored research and clinical trial agreements                          
License, Clinical Trial and Sponsored Research Agreements                          
Research and development expense                       4,162 6,989
Fred Hutchinson Cancer Center | Sponsored research and clinical trial agreements | CD20 (MB-106)                          
License, Clinical Trial and Sponsored Research Agreements                          
Milestones payable   $ 5,300                      
Additional milestone payments       $ 2,200   $ 1,800              
Research and development expense                       1,254 1,987
Fred Hutchinson Cancer Center | Clinical Trial Agreement | CD20 (MB-106)                          
License, Clinical Trial and Sponsored Research Agreements                          
Research and development expense                       1,300 2,000
St. Jude Children's Research Hospital | Sponsored research and clinical trial agreements | ST. Jude - XSCID                          
License, Clinical Trial and Sponsored Research Agreements                          
Research and development expense                       637 508
St. Jude Children's Research Hospital | Data Transfer Agreement | ST. Jude - XSCID                          
License, Clinical Trial and Sponsored Research Agreements                          
Upfront fees paid             $ 1,100            
Research and development expense                       600 500
Mayo Clinic | Sponsored research and clinical trial agreements                          
License, Clinical Trial and Sponsored Research Agreements                          
Milestones payable         $ 2,100                
Additional milestone payments     $ 100                    
Research and development expense                       551 968
Agreement term         2 years                
Leiden University Medical Center | Sponsored research and clinical trial agreements | RAG1 SCID (MB-110)                          
License, Clinical Trial and Sponsored Research Agreements                          
Milestones payable $ 500                        
Research and development expense                       $ 350 $ 505
Agreement term 5 years