Income Taxes - Significant Component of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Net operating loss carryforwards	$ 163,254	$ 154,634
Deferred tax assets:
Start-up and pre-clinical studies	8,683	11,011
Research and development credit carryforwards	40,345	40,486
Stock-based compensation	766	699
Capitalized acquisition costs	556	1,050
Lease liability	0	0
Depreciation	0	1
Capitalized research expenses	0	5,400
Other	(20)	0
Deferred Tax Assets Gross	213,584	213,281
Less valuation allowance	(213,584)	(213,281)
Total deferred tax assets	0	0
Deferred tax liabilities:
Right-of-use asset	0	0
Total deferred tax liabilities	0	0
Net deferred taxes	$ 0	$ 0