Share Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Fair Value of Share Options Granted to Employees And Directors

The fair value of each share option granted to employees and directors was estimated on the date of grant using the following assumptions:

	Year Ended December 31,
	2021		2020		2019
Risk free interest rate	0.51% - 1.17%		0.28% - 1.38%		1.43% - 2.61%
Expected dividend yield		—		—		—
Expected term (in years)	5.5 - 6.7		4.6 - 7.0		5.4 - 6.4
Expected volatility	76% - 79%		74% - 82%		55% - 58%

Summary of Share Option Plan Activity

The following table summarizes share option plan activity for the year ended December 31, 2021:

	Number of Ordinary Shares			Weighted- Average Exercise Price		Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2020		44,959,938		$	0.69			$	11,650
Granted		22,175,244		$	0.15
Exercised		—
Cancelled or forfeited		(3,556,620	)	$	0.64
Outstanding at December 31, 2021		63,578,562		$	0.50		7.4	$	—
Exercisable at December 31, 2021		32,701,811		$	0.71		6.3	$	—
Vested and expected to vest at December 31, 2021		60,345,324		$	0.51		7.4	$	—

Schedule of Nonvested Restricted Stock Units Activity

The following table summarizes restricted share unit activity for the 2020 ADS Plan for the year ended December 31, 2021 (in ordinary shares):

	Number of Shares			Weighted- Average Grant Date Fair Value
Non-vested at December 31, 2020		15,013,296		$	0.11
Granted		6,604,356		$	0.14
Vested and released		(7,876,356	)	$	0.11
Cancelled or forfeited		(653,448	)	$	0.13
Non-vested as of December 31, 2021		13,087,848		$	0.12

Schedule of Share Based Compensation Expense

Total share-based compensation expense is as follows (in thousands):

	Year Ended December 31,
	2021		2020		2019
Research and development	$	1,146	$	1,171	$	1,195
General and administrative		3,033		3,053		2,049
Total	$	4,179	$	4,224	$	3,244