Note 7 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]

	Year Ended December 31,
		2018	2019	2020
		$	$	$
Cayman Islands		3,305	3,843	3,805
U.S.		23,347	17,251	33,266
PRC		6,742	5,586	5,912
BVI		22,979	13,568	20,873
Australia		1,101	85	(35	)
Loss before income taxes		57,474	40,333	63,821

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended December 31,
	2018		2019		2020
	$		$		$
Loss before income tax	57,474		40,333		63,821
Expected income tax benefit	12,069		8,470		13,403
Tax rate difference	(2,121	)	(3,425	)	(4,653	)
Non-deductible expenses	(880	)	(5,228	)	(688	)
Research tax credits	-		2,360		641
Non-taxable income	75		-		120
Others	(143	)	(99	)	68
Change in valuation allowance	(9,000	)	(2,078	)	(8,891	)
Total income tax benefit	-		-		-

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2019		2020
	$		$
Deferred tax assets:
Net operating loss carryforward	14,345		18,034
Intangible asset	69		-
Deferral of tax deduction of R&D expenses	4,149		5,674
Share based compensation	404		1,768
Research tax credits	2,360		3,002
Lease liability obligation	519		452
Accruals and reserves	-		5
Total deferred tax assets	21,846		28,935
Deferred tax liabilities:
Right-of-use lease assets	(529	)	(473	)
Total deferred tax liabilities	(529	)	(473	)
Total gross deferred tax assets	21,317		28,462
Less: valuation allowance	(21,317	)	(28,462	)
Net deferred tax assets	-		-

Summary of Income Tax Contingencies [Table Text Block]

	Year Ended December 31,
		2018	2019	2020
		$	$	$
Beginning balance, as of January 1		219	624	956
Additions based on tax positions related to prior tax years		405	332	-
Reductions based on tax positions related to prior tax years		-	-	(226	)
Ending balance, as of December 31		624	956	730