Note 4 - Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2021

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	Amortized		Gross Unrealized					Estimated		Cash and Cash		Short-Term		Long-Term
	Cost		Gains		Losses			Fair Value		Equivalents		Investments		Investments
June 30, 2021
Cash at banks	$	88,955	$	—	$	—		$	88,955	$	88,955	$	—	$	—
Money market funds		76,311		—		—			76,311		76,311		—		—
U.S. Treasury securities		19,038		—		(6	)		19,032		—		9,996		9,036
Commercial paper		7,192		—		—			7,192		—		7,192		—
Corporate debt securities		7,436		—		(3	)		7,433		—		2,130		5,303
Total	$	198,932	$	—	$	(9	)	$	198,923	$	165,266	$	19,318	$	14,339

	Amortized		Gross Unrealized				Estimated		Cash and Cash		Short-Term		Long-Term
	Cost		Gains		Losses		Fair Value		Equivalents		Investments		Investments
December 31, 2020
Cash at banks	$	66,865	$	—	$	—	$	66,865	$	66,865	$	—	$	—
Money market funds		60,005		—		—		60,005		60,005		—		—
Total	$	126,870	$	—	$	—	$	126,870	$	126,870	$	—	$	—

Property, Plant and Equipment [Table Text Block]

	June 30, 2021			December 31, 2020
Laboratory equipment	$	2,199		$	1,759
Office and computer equipment		325			294
Construction in progress		2,583			—
Total property and equipment		5,107			2,053
Less: accumulated depreciation		(768	)		(573	)
Property and equipment, net	$	4,339		$	1,480

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

	June 30, 2021		December 31, 2020
Facilities	$	5,807	$	6,836
Office equipment		1		2
Right-of-use assets, net	$	5,808	$	6,838

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

	June 30, 2021			December 31, 2020
Purchased technology	$	20,300		$	20,300
Intellectual property		80			80
Total cost		20,380			20,380
Less: accumulated amortization		(5,885	)		(5,019	)
Intangible assets, net	$	14,495		$	15,361

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

Year Ending December 31,	Amount
2021 (six months remaining)	$	866
2022		1,731
2023		1,732
2024		1,732
2025		1,731
Thereafter		6,703
Total	$	14,495

Schedule of Accrued Liabilities [Table Text Block]

	June 30, 2021		December 31, 2020
Accrued compensation	$	1,508	$	1,618
Accrued clinical and manufacturing expenses		1,175		1,772
Accrued professional and consulting services		1,060		777
Other liabilities, current portion		394		632
Total	$	4,137	$	4,799