Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 680	$ 417
Less: Accumulated depreciation and amortization	(332)	(176)
Property and Equipment, Net	348	241
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	336	299
Office furniture
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	183	53
Computer equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	52	56
Software
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	33	9
Lab equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 76	$ 0

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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