Organization and summary of significant accounting policies - Additional Information (Details)		1 Months Ended	12 Months Ended
	Dec. 02, 2020	Jul. 31, 2020 shares	Dec. 31, 2021 USD ($) NumberOfSegment shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Jan. 01, 2021 USD ($)	Jul. 13, 2020 shares
Organization And Summary Of Significant Accounting Policies [Line Items]
Entity Incorporation, State or Country Code			DE
Company formation date			2007-03
Common Stock, Shares, Issued | shares		6,220,050	35,799,233	32,171,560
Preferred Stock, Shares Issued | shares			0	0
Stockholders' Equity, Reverse Stock Split	1-for-13
Accumulated deficit | $			$ (186,319,000)	$ (90,917,000)
Uncertain tax positions percentage			50.00%
Number of operating segment | NumberOfSegment			1
Impairment losses | $			$ 0	0	$ 0
Preferred return percentage			10.00%
Operating lease right-of-use-assets | $			$ 3,300,000	0		$ 4,100,000
Operating lease liabilities | $			1,389,000	0		1,100,000
Operating lease liabilities, less current portion | $			3,982,000	$ 0		$ 5,400,000
Accrued clinical trial cost | $			$ 6,200,000
Customer Concentration Risk | Customer | Revenue Benchmark
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Percentage			0.00%	100.00%	91.00%
Accumulated deficit
Organization And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit | $			$ 186,300,000
Class B Common Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Common unit, issued | shares			1,750,000
Common Stock, Shares, Issued | shares			1,492,059	1,492,059
Series D Convertible Preferred Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Common Stock, Shares, Issued | shares		59,164,808
Preferred Stock, Shares Issued | shares		59,164,808					140,626,711
Subsequent sale of convertible preferred stock to new investors, Shares | shares		140,626,711