Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Taxes

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences and tax loss and credit carry forwards that give rise to significant portions of deferred tax assets and liabilities at December 31, 2022 and 2021 are comprised of the following (in thousands):

	As of December 31, 2022		As of December 31, 2021
Deferred tax asset
Net operating loss carryforward	$	202,525	$	193,605
Research and development credit carry forwards		17,989		17,982
Capitalized research and experimental expenditures		9,144		—
Stock based compensation and other		18,021		23,637
Total deferred tax assets		247,679		235,224
Valuation Allowance		(247,679)		(235,224)
Deferred tax asset, net of allowance	$	—	$	—

Schedule of Effective Income Tax Rate Reconciliation

	As of December 31, 2022		As of December 31, 2021
Statutory federal income tax rate	21.0	%	21.0	%
State taxes, net of federal tax benefit	4.6	%	(2.0)	%
Tax rate differential on foreign income	(0.2)	%	0.1	%
Derivative gain or loss	(5.2)	%	(28.0)	%
Expiration of net operating losses	(2.6)	%	3.9	%
Other permanent items and true ups	(6.0)	%	0.1	%
R&D Credit	0.0	%	0.3	%
Change in rate	0.1	%	0.0	%
Change in valuation allowance	(11.7)	%	4.6	%
Income tax provision (benefit)	0.0	%	0.0	%

Schedule of Components of Income Tax Expense (Benefit)