Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accounts payable	$ 123	$ 271
Accrued goods and services	194	372
Accrued clinical trial costs	112	320
Accrued drug purchase costs		371
Accrued restructuring expenses		66	$ 921
Deferred tax incentives		1,314
Others	341
Total accounts payable, accrued expenses and other	$ 770	$ 2,714