Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Losses Before Provision for Income Taxes

Losses before provision for income taxes were as follows in each period presented:

	Year Ended December 31,
	2024			2023
	(in thousands)
United States	$	(85,311	)	$	(276,360	)
Foreign		(104	)		249
Total loss before provision for income taxes	$	(85,415	)	$	(276,111	)

Components of Provision for Income Taxes

The components of provision for income taxes were as follows in each period presented:

	Year Ended December 31,
	2024			2023
	(in thousands)
Current provision for income taxes:
State	$	—		$	1
Foreign		(12	)		14
Total current provision for income taxes	$	(12	)	$	15

Reconciliation of Statutory Tax Rates to Effective Tax Rates

A reconciliation of statutory tax rates to effective tax rates were as follows in each of the periods presented:

	Year Ended December 31,
	2024			2023
Federal income taxes at statutory rate		21.0	%		21.0	%
Research tax credits		(26.8	%)		4.3	%
Stock-based compensation		(16.2	%)		(4.5	%)
Other		(1.3	%)		(0.4	%)
Change in valuation allowance		23.3	%		(20.4	%)
Effective tax rate		0.0	%		0.0	%

Components of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities were as follows for each of the dates presented:

	As of December 31,
	2024			2023
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	259,376		$	323,581
Capitalized research expenses		61,113			72,229
Tax credit carryforwards		8,216			30,580
Stock-based compensation		5,789			14,033
Deferred revenue		14,709			17,018
Operating lease liabilities		9,403			12,035
License fees		4,794			5,926
Other		13,748			11,187
Total deferred tax assets		377,148			486,589
Valuation allowance		(368,401	)		(474,982	)
Total deferred tax assets		8,747			11,607
Deferred tax liabilities:
Operating lease assets		(8,747	)		(11,607	)
Total deferred tax liabilities		(8,747	)		(11,607	)
Net deferred tax assets (liabilities)	$	—		$	—

Under IRC Section 382, as amended, substantial restrictions exist on the utilization of net operating loss and tax credit carryforwards in the event a corporation experienced an “ownership change.” Generally, a Section 382 “ownership change” occurs if one or more stockholders or groups of stockholders who owns at least 5% of a corporation’s stock increases its ownership by more than 50 percentage points over its lowest ownership percentage within a specified testing period. Similar rules may apply under state tax laws. Accordingly, our ability to utilize net operating loss and tax credit carryforwards may be limited as a result of such ownership changes, and such a limitation could result in the expiration of carryforwards before they are utilized.

We have completed a Section 382 study of transactions in our stock through December 31, 2024. The study concluded that we have experienced ownership changes since inception with the most recent being on September 5, 2024. As a result of the ownership changes and imposed annual limitations on the amount of our tax attributes that may be utilized in a given period, should we generate taxable income, we have determined that we will have net operating losses and tax credits that will expire unutilized. We have reduced our net operating loss carryforwards and tax credit carryforwards in the above table as a result.

Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits

The changes in the balance of gross unrecognized tax benefits, which excludes interest and penalties, for the years ended December 31, 2023 and 2024 are as follows:

	(In thousands)
Balance as of January 1, 2023		150,965
Gross increases for tax positions related to current year		5,538
Gross increases for tax positions related to prior year		3,843
Gross decreases for tax positions related to prior year		—
Balance as of December 31, 2023		160,346
Gross increases for tax positions related to current year		1,011
Gross increases for tax positions related to prior year		647
Gross decreases for tax positions related to prior year		(124,071	)
Balance as of December 31, 2024	$	37,933