Commitments and Contingencies - Additional Information (Detail) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2021 USD ($)	Oct. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) Lease Installment	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Number of operating leases for real estate | Lease			3
Expiry of lease	Dec. 31, 2026	Dec. 31, 2026
Base rent due under lease	$ 4	$ 11
Percentage of increase rent per annum over lease term		3.50%
Percentage of base rent abated of lease term		50.00%
Right-of-use asset	247	$ 232	$ 868	$ 874
Operating lease liabilities	$ 247	$ 232	1,129
Finance leases			0
Astellas Pharma [Member]
Commitments And Contingencies [Line Items]
Minimum license fee payable			$ 75
Number of installments per year | Installment			2
Notice of termination under license agreement			30 days
San Diego | Corporate Headquarters [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date			2026-12
San Diego | Supplemental Office Space [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date			2026-12
Frederick, Maryland [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date			2025-11