Commitments and Contingencies - Summary of Commitments and Contingencies (Detail)	Sep. 30, 2019 USD ($)
Commitment And Contingencies [Line Items]
Total	$ 7,672,000
2019	4,540,000
2020	2,483,000
2021	483,000
2022	166,000
2023	0
Thereafter	0
Clinical research and trial obligations [Member]
Commitment And Contingencies [Line Items]
Total	4,319,000
2019	3,240,000
2020	1,079,000
2021	0
2022	0
2023	0
Thereafter	0
Biologics License Application (BLA) consulting services [Member]
Commitment And Contingencies [Line Items]
Total	1,142,000
2019	571,000
2020	571,000
2021	0
2022	0
2023	0
Thereafter	0
Statistical analysis and programming consulting services
Commitment And Contingencies [Line Items]
Total	435,000
2019	218,000
2020	217,000
2021	0
2022	0
2023	0
Thereafter	0
Employment Agreements [Member]
Commitment And Contingencies [Line Items]
Total	1,482,000
2019	249,000
2020	584,000
2021	483,000
2022	166,000
2023	0
Thereafter	0
Insurance premium financing agreement
Commitment And Contingencies [Line Items]
Total	294,000
2019	262,000
2020	32,000
2021	0
2022	0
2023	0
Thereafter	$ 0