Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accounts payable	$ 208	$ 271
Accrued goods and services	216	372
Accrued clinical trial costs	155	320
Accrued drug purchase costs	371	371
Accrued restructuring expenses	15	66	$ 1,056	$ 921
Deferred tax incentives	1,314	1,314
Total accounts payable, accrued expenses and other	$ 2,279	$ 2,714