The Company’s equity incentive plans, the 2018 Long Term Incentive Plan, as amended (the “2018 LTIP”), 2020 Employment Inducement Incentive Plan, as amended (the “2020 EIIP”), and previously, the Amended and Restated 2012 Long Term Incentive Plan (the “2012 LTIP”), reserve ordinary shares for the issuance of stock options, stock appreciation rights, restricted shares, RSUs, performance bonus awards, performance share units awards, dividend equivalents and other share or cash-based awards to eligible individuals. Options granted under each of the 2018 LTIP, 2020 EIIP, and 2012 LTIP expire no later than ten years from the date of grant.

In May 2025, the Company’s shareholders approved an amendment to the 2018 LTIP to increase the number of ordinary shares available for issuance under the 2018 LTIP by 2,000,000 ordinary shares. As of June 30, 2025, the number of ordinary shares authorized under the 2018 LTIP was 18,620,433. Upon adoption of the 2018 LTIP, no new awards are permitted under the 2012 LTIP.

As of June 30, 2025, the number of ordinary shares authorized under the 2020 EIIP was 1,485,000 and 341,584 ordinary shares remained available for future awards under the 2020 EIIP. The Company’s Board of Directors has adopted a series of amendments to increase the ordinary shares available for issuance under the 2020 EIIP and it reserves the right to both amend the 2020 EIIP to increase the number of ordinary shares available and make additional awards to key new hires.

The Company’s option awards generally vest over four years, while RSU awards generally vest over either two or three years. As of June 30, 2025, 4,015,538 ordinary shares remained available for grant under the Company’s equity incentive plans.

Share-based compensation expense recorded in these Condensed Consolidated Financial Statements was based on awards granted under the 2012 LTIP, the 2018 LTIP, and the 2020 EIIP. The estimated forfeiture rate as of June 30, 2025 was 11%. Changes in our estimates and assumptions relating to forfeitures may cause us to realize changes in stock-based compensation expense in the future.

The amount of unearned share-based compensation related to unvested stock options at June 30, 2025, is $72.2 million. The weighted-average period over which this unearned share-based compensation is expected to be recognized is 2.79 years.


	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Research and development	$	4,674	$	5,634	$	9,519	$	11,089
General and administrative	5,663		6,407		11,767		13,335
Restructuring costs (1)	2,081		—		2,081		—
Total share-based compensation expense	$	12,418	$	12,041	$	23,367	$	24,424

(1)Restructuring costs for the three and six months ended June 30, 2025 includes $2.1 million of share-based compensation expense related to the contractual acceleration of vesting of certain option awards granted to executive officers.

The Company recognized tax benefits from share-based awards of $2.4 million and $2.1 million for the three months ended June 30, 2025 and 2024, respectively, and $4.4 million and $4.3 million for the six months ended June 30, 2025 and 2024, respectively.

The fair value of the options granted to employees and non-employee directors during the six months ended June 30, 2025 and 2024 was estimated as of the grant date using the Black-Scholes option-pricing model using the key assumptions listed in the following table.


	Three Months Ended June 30,						Six Months Ended June 30,
	2025			2024			2025			2024
Expected term (in years)	4.81	‘-	5.76	4.60	‘-	5.56	4.78	-	5.76	4.60		-	5.56
Expected volatility	77.7%	‘-	79.0%	74.5%	‘-	77.8%	76.5%	-	79.0%	74.5	%	-	78.6%
Risk-free interest rate	3.8%	‘-	4.2%	4.4%	‘-	4.7%	3.8%	-	4.4%	3.8	%	-	4.7%
Expected dividend yield	—%			—%			—%			—%
Weighted average grant date fair value	$4.77			$14.58			$9.49			$19.21

The fair value of employee stock options is amortized on a straight-line basis over the requisite service period for each award. Each of the inputs discussed above is subjective and generally requires management judgment to determine.


	Options	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2024	11,107,373	$	28.70	6.16	$	3,401
Granted	2,086,686	14.26
Exercised	—	—
Forfeited	(87,987)	29.37
Expired	(211,427)	25.64
Outstanding at June 30, 2025	12,894,645	$	26.41	4.54	$	—
Vested and expected to vest at June 30, 2025	12,248,274	$	26.57	4.46	$	—
Vested at June 30, 2025	8,525,916	$	26.47	3.82	$	—

The total intrinsic value of options exercised was nil and $0.6 million during the three months ended June 30, 2025 and 2024, respectively, and nil and $1.0 million during the six months ended June 30, 2025 and 2024, respectively, determined as of the date of exercise.


	Number of Units	Weighted Average Grant-Date Fair Value		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Unvested at December 31, 2024	6,000	$	51.80	0.71	$	83
Units Granted	286,974	14.90
Units Vested	—	—
Units Forfeited	(9,667)	14.95
Unvested at June 30, 2025	283,307	$	15.68	1.71	$	1,720
Unvested and expected to vest at June 30, 2025	233,340	$	15.84	1.62	$	1,416

The fair value of RSUs was determined on the date of grant based on the market price of the Company’s ordinary shares as of that date. The fair value of the RSUs is recognized as an expense on a straight-line basis over the vesting period of each RSU. Upon the vesting of the RSUs, a portion of the shares vested are sold by the employee to satisfy employee withholding tax requirements (sell-to-cover). As of June 30, 2025, total compensation cost not yet recognized related to unvested RSUs was $3.7 million, which is expected to be recognized over a weighted-average period of 2.70 years. RSUs settle into ordinary shares upon vesting.