Annual report pursuant to Section 13 and 15(d)

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail)

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Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]    
Property and equipment, gross $ 1,606,154 $ 1,606,154
Accumulated depreciation and amortization (1,584,495) (1,518,692)
Property and equipment, net 21,659 87,462
Furniture and Fixtures [Member]    
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 20,742 20,742
Laboratory Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 812,215 812,215
Leasehold Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 487,871 487,871
Office and Computer Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Property and equipment, gross $ 285,326 $ 285,326