Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Additional Information (Details)

v3.20.1
Commitments and Contingencies - Additional Information (Details)
 3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Faculty
Mar. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2019
USD ($)
Commitments and Contingencies [Line Items]        
Research and development expense $ 4,620,000 $ 2,761,000    
Manufacturing agreements, maximum amount committed $ 2,000,000      
Operating Lease Agreement        
Commitments and Contingencies [Line Items]        
Operating lease, description The lease term commenced in May 2019 and will expire in July 2022.      
Lease commencement period 2019-05      
Lease expiration period 2022-07      
Initial annual base rent $ 261,000      
Percentage of annual increase of base rent 2.00%      
Rent expense $ 67,000      
Research Service Agreement | Children's Hospital of Philadelphia        
Commitments and Contingencies [Line Items]        
Research and development expense 0 179,000    
Amounts due to agreement 0      
Penn Agreement        
Commitments and Contingencies [Line Items]        
Amounts due to agreement 0      
Obligation to be paid $ 2,000,000      
Payment term 3 years      
Payment commencement date 2018-08      
License maintenance fee $ 10,000      
Out-of-pocket expenses reimbursed     $ 89,000  
Other amounts paid to agreement     $ 0  
Total milestone payments 20,000,000      
Penn Agreement | Common Stock        
Commitments and Contingencies [Line Items]        
Number of shares issued, shares | shares     481,318,000  
Number of shares issued, value     $ 1,155,000  
Sponsored Research Agreements | Penn        
Commitments and Contingencies [Line Items]        
Research and development expense 603,000 710,000    
Obligation to be paid $ 8,524,000      
Number of faculty member | Faculty 2      
Funding term 3 years      
Funding term end date 2021-04      
Sponsored Research Agreements | Penn | Prepaid Expenses and Other Current Assets        
Commitments and Contingencies [Line Items]        
Advance payments $ 985,000     $ 1,588,000
Master Translational Research Services Agreement        
Commitments and Contingencies [Line Items]        
Research and development expense 711,000 1,067,000    
Maximum research and development expense incurred 450,000      
Subscription and Technology Transfer Agreement        
Commitments and Contingencies [Line Items]        
Expense related to agreement $ 0 $ 0