Selected Balance Sheet Information - Schedule of prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Selected Balance Sheet Information
Prepaid insurances	$ 639	$ 549
Prepaid clinical research organizations	470	48
Stock sales receivable	469	3
Prepaid consulting, subscriptions and other expenses	90	134
Prepaid manufacturing expenses	39	622
Prepaid conferences and travel	0	25
Total	$ 1,707	$ 1,381

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Sum of the amount paid in advance for clinical research organization.

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Amount of Prepaid Manufacturing Expense.

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