Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Prepaid manufacturing and clinical expenses	$ 243	$ 488
Prepaid insurance	504	395
Prepaid license	25	100
Prepaid taxes		74
Other	119	76
Total Prepaid Expenses and Other Current Assets	$ 891	$ 1,133

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

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Name:	us-gaap_PrepaidTaxes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant