Accrued Expenses and Other Current Liabilities and Other Long-Term Liabilities - Accrued Expenses and Other Current Liabilities and Other Long-term Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Accrued expenses and other current liabilities:
Accrued research and development expenses	$ 6,936	$ 3,617
Accrued payroll and related expenses	3,894	3,274
Accrued clinical manufacturing	3,447	1,901
Accrued professional fees	759	507
Accrued other	884	593
Accrued expenses	15,920	9,892
Other long-term liabilities:
Uncertain tax positions	1,746	1,792
Accrued rent expense	900	593
Capital lease obligation	200	293
Asset retirement obligation	254	217
Other long-term liabilities	$ 3,100	$ 2,895