Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 175	$ 154
Less: accumulated depreciation and amortization	(126)	(113)
Property and equipment, net	49	41
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	5	5
Office Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	13	13
Computer Hardware
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	32	11
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 125	$ 125