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Accrued Expenses and Other - Schedule of Accrued Expenses and Other (Detail) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Payables And Accruals [Abstract]    
Accrued research and development expenses $ 310 $ 1,526
Accrued payroll and related expenses 798 2,291
Accrued professional fees 355 221
Accrued other 256 223
Total accrued expenses and other $ 1,719 $ 4,261