Selected Balance Sheet Information - Schedule of prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Selected Balance Sheet Information
Prepaid clinical research organizations	$ 1,182	$ 470
Prepaid consulting, subscriptions and other expenses	157	90
Prepaid insurances	83	639
Stock sales receivable	0	469
Prepaid manufacturing expenses	0	39
Total	$ 1,422	$ 1,707

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

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Sum of the amount paid in advance for consulting, subscriptions and other expenses.

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Amount of Prepaid Manufacturing Expense.

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Amount, after allowance, of receivables classified as other, due within one year or the operating cycle, if longer.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for insurance that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

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