Note 4 - Property and Equipment, Net - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property and equipment	$ 1,106	$ 1,090
Accumulated depreciation	(1,001)	(827)
Property and equipment, net	105	263
Computer Equipment and Software [Member]
Property and equipment	227	211
Furniture and Fixtures [Member]
Property and equipment	365	365
Laboratory Equipment [Member]
Property and equipment	$ 514	$ 514

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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