Quarterly report pursuant to Section 13 or 15(d)

Research and Development Agreements - Additional Information (Detail)

v3.8.0.1
Research and Development Agreements - Additional Information (Detail) - USD ($)
 1 Months Ended 3 Months Ended 77 Months Ended
Aug. 31, 2017
Jun. 23, 2017
Sep. 30, 2016
Nov. 30, 2011
Mar. 31, 2018
Sep. 30, 2017
Mar. 31, 2017
Mar. 31, 2018
Dec. 31, 2017
Oct. 31, 2016
Research And Development Collaboration Agreements [Line Items]                    
Date when performance obligations are expected to be fulfilled and revenue fully recognized.         Jun. 30, 2019          
Revenue remaining performance obligations not yet satisfied         $ 5,100,000     $ 5,100,000    
Research and development revenue         231,000   $ 1,760,000      
Accounts receivable from Takeda         4,000,000     4,000,000 $ 0  
Grant revenue         251,000   125,000      
Other Collaboration Agreements                    
Research And Development Collaboration Agreements [Line Items]                    
Research and development revenue         68,000   500,000      
Other Collaboration Agreements | ETBs                    
Research And Development Collaboration Agreements [Line Items]                    
Research and development revenue     $ 500,000              
Contingent milestone payment upon delivery and acceptance of additional ETB materials         250,000     250,000    
Takeda Pharmaceuticals Inc                    
Research And Development Collaboration Agreements [Line Items]                    
Aggregate Purchase Price   $ 20,000,000                
Takeda Pharmaceuticals Inc | Takeda Collaboration Agreement                    
Research And Development Collaboration Agreements [Line Items]                    
Payment for technology access fees and cost reimbursement                   $ 2,000,000
Research and development revenue         11,000   1,300,000      
Takeda Pharmaceuticals Inc | Takeda Multi Target Agreement                    
Research And Development Collaboration Agreements [Line Items]                    
Research and development revenue         152,000   0      
Upfront technology access fee         1,000,000          
Additional contingent milestone payments upon designation of each of two targets         2,000,000     2,000,000    
Accounts receivable from Takeda         4,000,000     4,000,000 $ 4,000  
Aggregate milestone payments upon exercise of option to license ETBS         25,000,000     25,000,000    
Additional preclinical, clinical development and commercialization milestone payments entitled to potentially receive         547,000,000     547,000,000    
Contractual contingency fees         10,000,000          
Proceeds from signing of stock purchase agreement           $ 20,000,000        
Aggregate Purchase Price $ 20,000,000                  
Cancer Prevention and Research Institute of Texas | ETB MT-3724 | Grant Agreements                    
Research And Development Collaboration Agreements [Line Items]                    
Product development grant awarded       $ 10,600,000            
Aggregate proceeds received from award granted               $ 9,500,000    
Cancer Prevention and Research Institute of Texas | ETB MT-3724 | Product Development Grant | Grant Agreements                    
Research And Development Collaboration Agreements [Line Items]                    
Grant revenue         $ 251,000   $ 125,000