Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12.Income Taxes

There is no provision for income taxes because the Company has incurred operating losses since inception. The reported amounts of income tax expense for the years ended December 31, 2023 and 2022 differ from the amounts that would result from applying domestic federal statutory tax rates to pretax losses primarily because of the changes in the valuation allowance. Significant components of the Company’s deferred tax assets at December 31, 2023 and 2022 are as follows:

	December 31,
(in thousands)	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	148,009		$	171,070
Start-up and pre-clinical studies		13,754			17,204
Research and development credit carryforwards		39,838			40,116
Stock-based compensation		681			698
Capitalized acquisition costs		1,570			2,180
Lease liability		—			618
Depreciation		1			239
Capitalized research expenses		7,176			5,156
Other		2			27
		211,031			237,308
Less valuation allowance		(211,031	)		(236,827	)
Total deferred tax assets		—			481
Right-of-use asset		—			(481	)
Total deferred tax liabilities	$	—		$	(481	)
Net deferred taxes	$	—		$	—

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. At December 31, 2023, the Company has aggregate net operating loss carryforwards for federal tax purposes of approximately $704.9 million, of which approximately $341.7 million expire at various dates through December 31, 2037 and approximately $363.2 million can be carried forward indefinitely. The Company is reducing its approximately $497.9 million of state net operating loss carryforwards to $0 as these state net operating loss carryforwards all related to Massachusetts filings and, as of December 31, 2023 the Company no longer had any employees or property in Massachusetts and, as a result, the Company will no longer have income tax nexus in Massachusetts or an income tax filing obligation after the year ended December 31, 2023. Additionally, the Company has approximately $39.8 million of federal and state research and development credits at December 31, 2023, expiring in varying amounts through 2043, which may be available to reduce future taxes. The Company has reduced its Massachusetts credits carryforward to $0.

The Company has provided a valuation allowance for the full amount of its net deferred tax assets since it is more likely than not that these future benefits will not be realized. However, these deferred tax assets may be available to offset future income tax liabilities and expenses. The valuation allowance decreased by $25.8 million in 2023 due primarily to the reduction of Massachusetts net operating loss carryforwards and Massachusetts research and development credits.

Income taxes using the federal statutory income tax rate differ from the Company’s effective tax rate primarily due to non-deductible expenses related to the Company’s issuance of warrants along with the change in the valuation allowance on deferred tax assets.

A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows:

	Year Ended December 31,
(in thousands)	2023			2022
Federal income tax at statutory rates		21	%		21	%
State income tax, net of federal tax benefit		(92	)%		3	%
Research and development credits		2	%		2	%
Research and development true-up		(1	)%		(2	)%
Stock-based compensation	—%				(1	)%
Federal/state rate change		(3	)%		(5	)%
Change in valuation allowance		73	%		(18	)%
Effective tax rate		—	%		—	%

The Company adopted ASC 740, Accounting for Uncertain Tax Positions on January 1, 2007. ASC 740 clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements in accordance with FASB Statement No. 109, “Accounting for Income Taxes.” ASC 740 prescribes a recognition threshold and measurement of a tax position taken or expected to be taken in a tax return. The Company did not establish any additional reserves for uncertain tax liabilities upon adoption of ASC 740. There were no adjustments to its uncertain tax positions in the years ended December 31, 2023 and 2022.

The Company has not recognized any interest and penalties in the statements of operations because of the Company’s net operating losses and tax credits that are available to be carried forward. When necessary, the Company will account for interest and penalties related to uncertain tax positions as part of its provision for federal and state income taxes. The Company does not expect the amounts of unrecognized benefits will change significantly within the next twelve months.

The Company is currently open to audit under the statute of limitations by the Internal Revenue Service and state jurisdictions for the years ended December 31, 1999 through 2023 to the extent net operating losses continue to be carried forward to 2023.

Beginning in 2022, the Tax Cuts and Jobs Act of 2017, or the Tax Act, eliminated the option to deduct research and development expenditures immediately in the year incurred and requires taxpayers to capitalize and amortize them over five years pursuant to IRC Section 174. The mandatory capitalization requirement had no impact to the overall deferred tax assets due to the Company's loss position and full valuation allowance.