Property and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Property and equipment
Less accumulated depreciation	$ (1,646)	$ (1,123)
Property and equipment, net	1,204	1,690
Depreciation and amortization	455	457
Computer software and equipment
Property and equipment
Property and equipment, gross	15	15
Office equipment and furniture
Property and equipment
Property and equipment, gross	176	176
Laboratory equipment
Property and equipment
Property and equipment, gross	1,597	1,571
Leasehold improvements
Property and equipment
Property and equipment, gross	1,051	$ 1,051
Construction in progress
Property and equipment
Property and equipment, gross	$ 11

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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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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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.

+ References

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