Note 4 - Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	March 31, 2021
	Amortized		Gross Unrealized					Estimated		Cash and Cash		Short-Term		Long-Term
	Cost		Gains		Losses			Fair Value		Equivalents		Investments		Investments
Cash at banks	$	74,187	$	—	$	—		$	74,187	$	74,187	$	—	$	—
Money market funds		83,124		—		—			83,124		83,124		—		—
U.S. Treasury securities		4,998		—		(1	)		4,997		—		4,997		—
Commercial paper		8,388		—		—			8,388		—		8,388		—
Corporate debt securities		6,558		—		(4	)		6,554						6,554
Total	$	177,255	$	—	$	(5	)	$	177,250	$	157,311	$	13,385	$	6,554

Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]

	March 31, 2021		December 31, 2020
Royalties receivable	$	468	$	334
Customer service contracts - billed		232		—
Accounts receivable	$	700	$	334

Property, Plant and Equipment [Table Text Block]

	March 31, 2021			December 31, 2020
Laboratory equipment	$	2,072		$	1,759
Office and computer equipment		302			294
Construction in progress		519			—
Total property and equipment		2,893			2,053
Less: accumulated depreciation		(648	)		(573	)
Property and equipment, net	$	2,245		$	1,480

Lessee, Operating Lease, Right-of-Use Assets [Table Text Block]

	March 31, 2021		December 31, 2020
Facilities	$	6,348	$	6,836
Office equipment		2		2
Right-of-use assets, net	$	6,350	$	6,838

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	March 31, 2021			December 31, 2020
Purchased technology	$	20,300		$	20,300
Intellectual property		80			80
Total cost		20,380			20,380
Less: accumulated amortization		(5,452	)		(5,019	)
Intangible assets, net	$	14,928		$	15,361

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Year Ending December 31,	Amount
2021 (nine months remaining)	$	1,299
2022		1,731
2023		1,732
2024		1,732
2025		1,731
Thereafter		6,703
Total	$	14,928

Schedule of Accrued Liabilities [Table Text Block]

	March 31, 2021		December 31, 2020
Accrued compensation	$	1,044	$	1,618
Accrued clinical and manufacturing expenses		889		1,772
Accrued professional and consulting services		906		777
Other liabilities, current portion		337		632
Total	$	3,176	$	4,799