License and collaboration agreements - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Jun. 25, 2020
Dec. 19, 2018
Jun. 30, 2020
Apr. 30, 2020
Dec. 31, 2021
Dec. 31, 2020
Jun. 30, 2018
Expense related to milestone payments         $ 0 $ 0  
KU Leuven [Member]              
Collaboration expire period 2 years 6 months            
Emory license agreement [Member] | Emory university [Member]              
Non-refundable payment     $ 150,000        
Long term purchase commitment additional obligation to be paid     35,000        
Research plan funding amount     $ 270,000        
Research plan expiry period     1 year        
Long term purchase commitment period description         The research plan terminates one year from the effective date, with the Company having an option to extend for a second year    
Expense related to milestone payments         $ 195,000 4,500,000  
Payments for royalties         0 0  
Emory license agreement [Member] | Emory university [Member] | Maximum [Member]              
Aggregate payments             $ 125,000,000.0
Luxna license agreement [Member] | Luxna biotech Co Ltd [Member]              
Expense related to milestone payments         500,000 0  
Payments for royalties         $ 0 0  
Luxna license agreement [Member] | Luxna biotech Co Ltd [Member] | Maximum [Member]              
Aggregate payments   $ 55,500,000          
Luxna license agreement [Member] | Research and Development [Member] | Luxna biotech Co Ltd [Member]              
Upfront license fees paid   $ 600,000          
Non-refundable payment       $ 200,000      
Katholieke Universiteit Leuven License Agreement [Member] | Katholieke Universiteit Leuven [Member]              
Non-refundable payment $ 30,000,000.0            
Long term purchase commitment period description         Unless terminated earlier by either party, the agreement shall continue until the expiration of the last to expire royalty term, which is the later of the expiration or termination of the last valid patent claim covering the manufacture, use, sale or importation of the licensed product in a particular country or 10 years after the first commercial sale of a licensed product.    
First commercial sale of a licensed product period 10 years            
Katholieke Universiteit Leuven License Agreement [Member] | Katholieke Universiteit Leuven [Member] | Maximum [Member]              
Non-refundable payment $ 32,000,000.0            
Merck License and Research Collaboration | Merck              
Revenue recognized from collaborative arrangements         $ 4,400,000 0  
Merck License and Research Collaboration | Merck | Maximum [Member]              
Milestone payments and royalties receivable           $ 458,000,000.0