Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accounts payable	$ 839	$ 271
Accrued goods and services	382	372
Accrued clinical trial costs	288	320
Accrued drug purchase costs	371	371
Accrued restructuring expenses	46	66	$ 209	$ 921
Deferred tax incentives	1,314	1,314
Total accounts payable, accrued expenses and other	$ 3,240	$ 2,714