Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Total revenue	$ 1,015	$ 145
Costs and expenses:
Cost of goods sold	0	4
Research and development	8,558	9,809
Selling, general and administrative	5,087	5,861
Total costs and expenses	13,645	15,674
Operating loss	(12,630)	(15,529)
Other income (expense):
Interest income	9	21
Gain on extinguishment of Paycheck Protection Program note payable	0	509
Interest expense	0	(3)
Other expense	(2)	(2)
Total other income, net	7	525
Net loss	$ (12,623)	$ (15,004)
Net loss per share, basic and diluted (in dollars per share)	$ (0.75)	$ (1.48)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	16,917,664	10,118,682
Product [Member]
Revenue:
Total revenue	$ 1	$ 13
Collaboration Agreement [Member]
Revenue:
Total revenue	$ 1,014	$ 132