0000950170-23-063023 | 10-Q | XBRL Viewer | Cyclerion Therapeutics INC

Subsequent Events	9 Months Ended
Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events The Company has evaluated all events and transactions that occurred after the balance sheet date through the date the consolidated financial statements were issued and determined that there were no such events requiring recognition or disclosure in the consolidated financial statements.

Subsequent Events

9 Months Ended

Sep. 30, 2023

16. Subsequent Events

The Company has evaluated all events and transactions that occurred after the balance sheet date through the date the consolidated financial statements were issued and determined that there were no such events requiring recognition or disclosure in the consolidated financial statements.

Workforce Reduction (Details) $ in Thousands		9 Months Ended
Workforce Reduction (Details) $ in Thousands	Oct. 06, 2022 USD ($) Employees	Sep. 30, 2023 USD ($)
Restructuring Cost and Reserve [Line Items]
Beginning of period		$ (809)
Charges		(565)
Amount paid		1,074
Adjustments		0
End of period		(300)
Workforce reduction
Restructuring Cost and Reserve [Line Items]
Beginning of period		(809)
Charges		(565)
Amount paid		1,074
Adjustments		0
End of period		$ (300)
Current workforce reductions \| October 2022 Current Workforce Reductions
Restructuring Cost and Reserve [Line Items]
Reduction in workforce, number of employees \| Employees	13
Restructuring costs	$ 1,300

Commitments and Contingencies	9 Months Ended
Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Guarantees On September 6, 2018, Cyclerion was incorporated in Massachusetts and its officers and directors are indemnified for certain events or occurrences while they are serving in such capacity. The Company enters into certain agreements with other parties in the ordinary course of business that contain indemnification provisions. These typically include agreements with directors and officers, business partners, contractors, clinical sites and customers. Under these provisions, the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company’s activities. These indemnification provisions generally survive termination of the underlying agreements. The maximum potential amount of future payments the Company could be required to make under these indemnification provisions is unlimited. However, to date the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. As a result, the estimated fair value of these obligations is minimal. Accordingly, the Company did not have any liabilities recorded for these obligations as of September 30, 2023 and December 31, 2022.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and Contingencies

Guarantees

On September 6, 2018, Cyclerion was incorporated in Massachusetts and its officers and directors are indemnified for certain events or occurrences while they are serving in such capacity.

The Company enters into certain agreements with other parties in the ordinary course of business that contain indemnification provisions. These typically include agreements with directors and officers, business partners, contractors, clinical sites and customers. Under these provisions, the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company’s activities. These indemnification provisions generally survive termination of the underlying agreements. The maximum potential amount of future payments the Company could be required to make under these indemnification provisions is unlimited. However, to date the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. As a result, the estimated fair value of these obligations is minimal. Accordingly, the Company did not have any liabilities recorded for these obligations as of September 30, 2023 and December 31, 2022.

Discontinued Operations - Schedule of transaction consideration received from the sale of the Program Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Disposal Group, Including Discontinued Operation, Classified Balance Sheet Disclosures [Abstract]
Closing payment	$ 8,000
Expense reimbursement	2,402
Investment in Tisento Parent	5,350
Gross transaction consideration from the sale	15,752	$ 0
Net assets sold	0
Net gain (loss) from discontinued operations	$ 15,752

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2023

Accrued Liabilities and Other Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities

7. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	September 30,		December 31,
	2023		2022
Accrued incentive compensation	$	—	$	238
Salaries		14		246
Accrued vacation		17		186
Professional fees		676		835
Accrued severance and benefit costs		300		809
Other		158		68
Accrued expenses and other current liabilities	$	1,165	$	2,382

Nature of Business

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

1. Nature of Business

Nature of Operations

Cyclerion Therapeutics, Inc. (“Cyclerion”, the “Company” or “we”) is a biopharmaceutical company on a mission to develop treatments for serious diseases. Our portfolio includes novel soluble guanylate cyclase ("sGC") stimulators that modulate a key node in a fundamental signaling network in both the central nervous system ("CNS") and the periphery. The nitric oxide ("NO") soluble guanylate cyclase ("sGC") cyclic guanosine monophosphate ("cGMP") signaling pathway is a fundamental mechanism that precisely controls key aspects of physiology throughout the body. The NO-sGC-cGMP pathway regulates diverse and critical biological functions and has been successfully targeted with several drugs.

Praliciguat is a systemic sGC stimulator that is licensed to Akebia Therapeutics Inc. ("Akebia") and being advanced in rare kidney disease. Olinciguat is a clinical-stage vascular sGC stimulator that the Company intends to out-license for cardiovascular diseases. Zagociguat is a clinical-stage CNS-penetrant sGC stimulator that has shown rapid improvement in cerebral blood flow, functional brain connectivity, brain response to visual stimulus, cognitive performance, and biomarkers associated mitochondrial function and inflammation in clinical studies. CY3018 is a CNS-targeted sGC stimulator that preferentially localizes to the brain and has a pharmacology profile that suggests its potential for the treatment of neuropsychiatric diseases and disorders. On July 28, 2023, the Company sold Zagociguat and CY3018 to Tisento Therapeutics, Inc. ("Tisento"), a newly formed private company focused on their development, in which Cyclerion currently holds a 10% equity stake received in partial consideration of such sale. See "Asset Purchase Agreement" and "Note 4" below. Cyclerion is actively evaluating other activities aimed at enhancing shareholder value, which may potentially include collaborations, licenses, mergers, acquisitions and/or other targeted investments.

Cyclerion GmbH, a wholly owned subsidiary, was incorporated in Zug, Switzerland on May 3, 2019. The functional currency is the Swiss franc. Subsequent to September 30, 2023, the liquidation process for Cyclerion GmbH has been concluded and the subsidiary is pending deregistration from the commercial registry.

Cyclerion Securities Corporation, a wholly owned subsidiary, was incorporated in Massachusetts on November 15, 2019 and was granted securities corporation status in Massachusetts for the 2019 tax year. Cyclerion Securities Corporation has no employees.

Company Overview

The Company’s mission is to develop treatments for serious diseases.

Praliciguat is an orally administered, once-daily systemic sGC stimulator. On June 3, 2021, Cyclerion entered into a license agreement (as defined below) with Akebia relating to the exclusive worldwide license to Akebia of our rights to the development, manufacture, medical affairs and commercialization of pharmaceutical products containing praliciguat and other related products and forms thereof enumerated in such agreement. Cyclerion is eligible to receive up to $585 million in total potential future development, regulatory, and commercialization milestone payments. Cyclerion is also eligible to receive tiered, sales-based royalties ranging from single-digit to high-teen percentages.

Olinciguat is an orally administered, once-daily, vascular sGC stimulator that was evaluated in a Phase 2 study of participants with sickle cell disease. The Company released topline results from this study in October 2020. Cyclerion intends to out-license olinciguat to an entity with strong cardiovascular and/or cardiopulmonary capabilities.

Zagociguat and CY3018 are orally administered CNS-penetrant sGC stimulators. On July 28, 2023, the Company sold zagociguat and CY3018 to Tisento in exchange for $8.0 million in cash consideration, $2.4 million as reimbursement for certain operating expenses related to zagociguat and CY3018 for the period between signing and

closing of the transaction, and 10% of all of Tisento's parent's outstanding equity securities. See "Asset Purchase Agreement" and "Note 4" below.

Cyclerion continues to evaluate other activities aimed at enhancing shareholder value, which may potentially include collaborations, licenses, mergers, acquisitions and/or other targeted investments. No such activities are currently pending as of the date of the filing.

Stock Purchase Agreement

In March 2023, we entered into a stock purchase agreement with the Company's Chief Executive Officer (the "CEO") pursuant to which he invested $5 million in cash for 225,000 shares of common stock and 351,037 shares of Series A Convertible Preferred Stock of the Company at a price of $8.68 per share (after giving effect to the 1-for-20 reverse stock split the Company implemented on May 15, 2023). Such Series A Convertible Preferred Stock is convertible into shares of our common stock on a one-to-one basis. The closing of the equity investment took place on May 19, 2023, and (to comply with Nasdaq listing requirements) our shareholders approved such convertibility on July 19, 2023.

Asset Purchase Agreement

On May 11, 2023, the Company entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with an investor group that included the CEO, JW Celtics Investment Corp and JW Cycle Inc. which subsequently changed their names to Tisento Therapeutics Holdings Inc.("Tisento Parent") and Tisento Therapeutics Inc. ("Tisento"). Upon the closing on July 28, 2023, of the transactions contemplated by the Asset Purchase Agreement, the Company sold to Tisento specified assets relating to the Company’s zagociguat and CY3018 programs (the "Program Assets") and Tisento assumed certain liabilities relating thereto, including, but not limited to (i) liabilities, costs and expenses arising after the date of the Asset Purchase Agreement relating to the employment of certain Cyclerion employees and the conduct of certain preclinical and clinical trial activities prior to the closing of the transactions contemplated by the Asset Purchase Agreement, and (ii) liabilities relating to such assets to the extent relating to the period after the closing of the transaction. In consideration for such sale and assumption, at such closing the Company received proceeds of $8.0 million as cash consideration, $2.4 million as reimbursement for certain operating expenses related to such assets for the period between signing and closing of the Asset Purchase Agreement, and shares of common stock of Tisento Parent comprising 10% of the then issued and outstanding equity securities of Tisento Parent immediately following such closing, subject to certain protections against dilution.

Reverse Stock Split

On May 15, 2023, the Company filed Articles of Amendment to the Company's Restated Articles of Organization with the Secretary of Commonwealth of Massachusetts to effect a 1-for-20 reverse stock split of the Company's issued and outstanding shares of common stock. The reverse stock split was reflected on the Nasdaq Capital Market beginning with the opening of trading on May 16, 2023. No fractional shares were issued in connection with the reverse stock split. All share amounts and per share amounts disclosed in this Quarterly Report on Form 10-Q have been adjusted retroactively to reflect the reverse stock split for all periods presented.

At-the-Market Shelf Registration Statement

On July 24, 2020, the Company filed a Registration Statement on Form S-3 (the “Shelf”) with the Securities and Exchange Commission (the “SEC”) in relation to the registration of common stock, preferred stock, debt securities, warrants and units of any combination thereof for an aggregate initial offering price not to exceed $150.0 million. The Shelf was declared effective as of July 31, 2020. The Shelf expired in July 31, 2023. On September 3, 2020, the Company entered into a Sales Agreement (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) with respect to an at-the-market offering (the “ATM Offering”) under the Shelf. Under the ATM Offering, the Company could offer and sell, from time to time at its sole discretion, shares of its common stock, having an aggregate offering price of up to $50.0 million through Jefferies as its sales agent. The Company agreed to pay Jefferies cash commissions of 3.0 percent of the gross proceeds of sales of common stock which could be sold under the Sales Agreement. Prior to January 1, 2022, the Company sold 3,353,059 shares of its common stock for

net proceeds of $12.5 million under the ATM Offering, since entering into the Sales Agreement. No shares of common stock have been issued or sold under the ATM Offering in 2022 or 2023.

Basis of Presentation

The condensed consolidated financial statements and the related disclosures are unaudited and have been prepared in accordance with accounting principles generally accepted in the U.S. Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022, which was filed with the Securities and Exchange Commission on March 22, 2023.

In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all normal recurring adjustments considered necessary for a fair presentation of the Company’s financial position and the results of its operations for the interim periods presented. The results of operations for the three and nine months ended September 30, 2023 and 2022 are not necessarily indicative of the results that may be expected for the full year or any other subsequent interim period.

The condensed consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries, Cyclerion GmbH, and Cyclerion Securities Corporation. All significant intercompany accounts and transactions have been eliminated in the preparation of the accompanying condensed consolidated financial statements.

Going Concern

At each reporting period, in accordance with Accounting Standards Codification ("ASC") 205-40, Going Concern, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs and comparing those needs to the current cash and cash equivalent balances. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern.

This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. In performing its analysis, management excluded certain elements of its operating plan that cannot be considered probable. Under ASC 205-40, the future receipt of potential funding from future partnerships, equity or debt issuances, certain cost reduction measures and the potential milestones from the Akebia agreement cannot be considered probable at this time because these plans are not entirely within the Company’s control and/or have not been approved by the Board of Directors as of the date of these consolidated financial statements.

The Company expects that its cash, cash equivalents and marketable securities as of September 30, 2023, will be sufficient to fund operations into 2025, however the Company will need to obtain additional funding to sustain operations as it expects to continue to generate operating losses for the foreseeable future. The Company's expectation to generate negative operating cash flows in the future and the need for additional funding to support its planned operations, raise substantial doubt regarding the Company’s ability to continue as a going concern. Management's plans to alleviate the conditions that raise substantial doubt include reduced spending, and the pursuit of additional capital. Management has concluded the likelihood that its plan to successfully obtain sufficient funding, or adequately reduce expenditures, while reasonably possible, is less than probable. Accordingly, the Company has concluded that substantial doubt exists about the Company’s ability to continue as a going concern.

The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.

Gain (loss) per share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Gain (loss) per share

11. Gain (loss) per share

Basic and diluted net gain (loss) per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Numerator:
Net loss from continuing operations (in thousands)	$	(5,908	)	$	(4,407	)	$	(10,899	)	$	(13,923	)
Net gain (loss) from discontinued operations (in thousands)		13,474			(6,089	)		7,330			(22,939	)
Total net gain (loss) (in thousands)		7,566			(10,496	)		(3,569	)		(36,862	)

Denominator:
Weighted average shares used in calculating net gain (loss) per share — basic (in thousands)		2,435			2,174			2,299			2,173
Weighted average shares used in calculating net gain (loss) per share — diluted (in thousands)		2,786			2,174			2,299			2,173

Net gain (loss) per share — basic
Net loss per share from continuing operations	$	(2.43	)	$	(2.03	)	$	(4.74	)	$	(6.41	)
Net gain (loss) per share from discontinued operations		5.53			(2.80	)		3.19			(10.56	)
Total gain (loss) per share	$	3.11		$	(4.83	)	$	(1.55	)	$	(16.96	)

Net gain (loss) per share — diluted
Net loss per share from continuing operations	$	(2.12	)	$	(2.03	)	$	(4.74	)	$	(6.41	)
Net gain (loss) per share from discontinued operations		4.84			(2.80	)		3.19			(10.56	)
Total gain (loss) per share	$	2.72		$	(4.83	)	$	(1.55	)	$	(16.96	)

Except for the three months ended September 30, 2023, we exclude shares of preferred stock, common stock related to stock options and RSUs from the calculation of diluted net loss per share since the inclusion of such shares would be anti-dilutive in each period. During the three months ended September 30, 2023, 351,037 shares of preferred stock are dilutive and included in the diluted shares. There was no preferred stock issued and outstanding during the three and nine months ended September 30, 2022.

The following table sets forth potential shares that were considered anti-dilutive for the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Preferred Stock		—		—		351,037		—
Stock Options		320,107		420,666		320,107		420,666
RSUs		—		2,624		—		2,624
		320,107		423,290		671,144		423,290

Fair Value of Financial Instruments (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Cash equivalents:
Total cash equivalents	$ 8,237	$ 12,357
Level 1
Cash equivalents:
Total cash equivalents	8,237	12,357
Money market funds
Cash equivalents:
Total cash equivalents	8,237	12,357
Money market funds \| Level 1
Cash equivalents:
Total cash equivalents	$ 8,237	$ 12,357

Other Investment

9 Months Ended

Sep. 30, 2023

Investments, All Other Investments [Abstract]

Other Investment

5. Other Investment

On July 28, 2023, the Company closed the transactions contemplated by the Asset Purchase Agreement receiving proceeds of $8.0 million as cash consideration, approximately $2.4 million as reimbursement for certain operating expenses related to zagociguat and CY3018 programs for the period between signing and closing of the transaction, and 10% of all of Tisento Parent's outstanding equity securities which fair value was determined to be $5.3 million at the time of closing. The Company’s investment in Tisento Parent does not provide it with significant influence over Tisento Parent.

The investment does not have a readily determinable fair value and therefore will be measured at cost minus impairment adjusted by observable price changes in orderly transactions for the identical or a similar investment of the same issuer. This investment will be measured at fair value on a nonrecurring basis when there are events or changes in circumstances that may have a significant adverse effect. An impairment loss is recognized in the consolidated statements of operations and comprehensive loss equal to the amount by which the carrying value exceeds the fair value of the investment. As of September 30, 2023, no impairment loss was recognized.

The initial fair value of the investment in Tisento Parent was determined by reference to the risk-adjusted net assets value using the discounted cash flow method. The estimated net assets value of Tisento Parent includes the cash generated/used from the operations and the proceeds from equity financing. Valuations were derived by reference to observable valuation measures for comparable companies or transactions, including weighted average cost of capital (21% to 23%), terminal decline rate (25% to 75%) and the discount rate referenced by a two-year treasury rate of 4.01%.

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (3,569)	$ (36,862)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on disposal of discontinued operations	(15,752)	0
Depreciation and amortization	0	65
Impairment Loss	3,304	0
Share-based compensation expense	964	5,128
Changes in operating assets and liabilities:
Accounts receivable	96	(127)
Prepaid expenses	79	392
Other current assets	140	(20)
Operating lease assets	107	138
Other assets	213	274
Accounts payable	(2,157)	(183)
Accrued research and development costs	(1,912)	(2,037)
Accrued expenses and other current liabilities	(1,217)	(336)
Net cash used in operating activities	(19,704)	(33,568)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net proceeds from disposal of discontinued operations	10,402	0
Net cash provided by investing activities	10,402	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock purchase agreement	5,000	0
Proceeds from exercises of stock options and ESPP	24	17
Net cash provided by financing activities	5,024	17
Effect of exchange rate changes on cash and cash equivalents	4	(5)
Net decrease in cash and cash equivalents	(4,274)	(33,556)
Cash and cash equivalents, beginning of period	13,382	53,961
Cash and cash equivalents, end of period	9,108	20,405
Supplemental cash flow disclosure:
Non-cash gain on disposal of discontinued operations	$ 5,350	$ 0

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Schedule of financial assets measured at fair value on a recurring basis and indicating the level of the fair value hierarchy

The Company’s cash equivalents are generally classified within Level 1 of the fair value hierarchy. The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values as of September 30, 2023, and December 31, 2022 (in thousands):


	Fair Value Measurements as of September 30, 2023:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	8,237	$	—	$	—	$	8,237
Cash equivalents	$	8,237	$	—	$	—	$	8,237


	Fair Value Measurements as of December 31, 2022:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	12,357	$	—	$	—	$	12,357
Cash equivalents	$	12,357	$	—	$	—	$	12,357

Share-based Compensation Plans - Summary of RSU Activity (Details) - Restricted Stock Units	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Number of Shares
Unvested as of December 31,2022 \| shares	40,772
Granted (in shares) \| shares	0
Vested (in shares) \| shares	(37,675)
Forfeited (in shares) \| shares	(3,097)
Unvested the end of the period (in shares) \| shares	0
Weighted-Average Grant Date Fair Value
Unvested as of December 31,2022 \| $ / shares	$ 15.3
Granted (in dollars per share) \| $ / shares	0
Vested (in dollars per share) \| $ / shares	15.11
Forfeited (in dollars per share) \| $ / shares	17.5
Unvested restricted common stock at the end of the period (in dollars per share) \| $ / shares	$ 0

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

The accounting policies of the Company are set forth in Note 2. Summary of Significant Accounting Policies to the consolidated financial statements contained in the Company’s 2022 Annual Report on Form 10-K for the fiscal year ended December 31, 2022.

Discontinued Operations

In accordance with ASC 205-20 “Presentation of Financial Statements: Discontinued Operations”, a disposal of a component of an entity or a group of components of an entity is required to be reported as discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. In the period in which the component meets held-for-sale or discontinued operations criteria the major current assets, non-current assets, current liabilities, and non-current liabilities shall be reported as components of total assets and liabilities separate from those balances of the continuing operations and disclosed in the notes to financial statements. At the same time, the results of all discontinued operations, less applicable income taxes, shall be reported as components of net loss separate from the net income (loss) of continuing operations.

The Program Assets met the definition of a discontinued operation. Accordingly, the Company has classified the results of the Program Assets as discontinued operations in its unaudited condensed consolidated statements of operations for all periods presented. All assets and liabilities associated with the Program Assets were classified as assets and liabilities of discontinued operations in the Note 4, "Discontinued Operations". All amounts included in the notes to the unaudited condensed consolidated financial statements relate to continuing operations unless otherwise noted. For additional information, see Note 4, “Discontinued Operations”.

Investment

The Company accounts for investments in equity securities without a readily determinable fair value at cost, minus impairment. If the Company identifies observable price changes in orderly transactions for an identical or a similar investment of the same issuer, the Company will measure the equity security at fair value as of the date that the observable transaction occurred in accordance with ASC Topic 321, Investments-Equity Securities.

Use of Estimates

The preparation of consolidated financial statements in accordance with U.S. generally accepted accounting principles ("GAAP") requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the amounts of expenses during the reported periods. On an ongoing basis, the Company’s management evaluates its estimates, judgments, and methodologies. Significant estimates and assumptions in the consolidated financial statements include those related to revenue, fair value determination of other investment, impairment of long-lived assets, valuation procedures for right-of-use ("ROU") assets and operating lease liabilities, income taxes, including the valuation allowance for deferred tax assets, research and development expenses, contingencies, share-based compensation and going concern. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ materially from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known.

New Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date.

Except as discussed elsewhere in the notes to the consolidated financial statements, the Company did not adopt any new accounting pronouncements during the nine months ended September 30, 2023 that had a material effect on its condensed consolidated financial statements.

In June 2016 the FASB issued ASU 2016-13, Financial Instruments-Credit Losses. This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. As a smaller reporting company, ASU 2016-13 became effective for the Company for fiscal years beginning after December 15, 2022. The Company adopted ASU 2016-13 in the first quarter of 2023, and the adoption of this standard did not have any impact on the Company's financial position or results of operations.

No other accounting standards known by the Company to be applicable to it that have been issued by the FASB or other standard-setting bodies and that do not require adoption until a future date are expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Discontinued Operations - Schedule of significant non-cash item for the discontinued operations that are included in the accompanying unaudited condensed consolidated statements of cash flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share-based compensation expense	$ 0	$ 306	$ 505	$ 937

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Liabilities and Other Liabilities [Abstract]
Accrued incentive compensation	$ 0	$ 238
Salaries	14	246
Accrued vacation	17	186
Professional fees	676	835
Accrued severance and benefit costs	300	809
Other	158	68
Accrued expenses and other current liabilities	$ 1,165	$ 2,382

Share-based Compensation Plans

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Share-based Compensation Plans

10. Share-based Compensation Plans

In 2019, Cyclerion adopted share-based compensation plans. Specifically, Cyclerion adopted the 2019 Employee Stock Purchase Plan (“2019 ESPP”) and the 2019 Equity Incentive Plan (“2019 Equity Plan”). Under the 2019 ESPP, eligible employees may use payroll deductions to purchase shares of stock in offerings under the plan, and thereby acquire an interest in the future of the Company. The 2019 Equity Plan provides for stock options and restricted stock units (“RSUs”).

Cyclerion mirrored two of Ironwood Pharmaceuticals, Inc's. ("Ironwood") existing plans, the Amended and Restated 2005 Stock Incentive Plan (“2005 Equity Plan”) and the Amended and Restated 2010 Employee, Director and Consultant Equity Incentive Plan (“2010 Equity Plan"). These mirror plans were adopted to facilitate the exchange of Ironwood equity awards for Cyclerion equity awards upon the tax-free spin-off of Ironwood's sGC business (the "Separation") as part of the equity conversion. As a result of the Separation and in accordance with the Employee Matters Agreement between Ironwood and Cyclerion entered into as part of the Separation, employees of both companies retained their existing Ironwood vested options and received a pro-rata share of Cyclerion options, regardless of which company employed them post-Separation. For employees that were ultimately employed by Cyclerion, unvested Ironwood options and RSUs were converted to unvested Cyclerion options and RSUs.

The following table provides share-based compensation reflected in the Company’s condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022 (in thousands):


	Three Months Ended September 30,					Nine Months Ended September 30,
	2023			2022		2023		2022
Research and development	$	(19	)	$	773	$	391	$	2,396
General and administrative		178			889		573		2,732
	$	159		$	1,662	$	964	$	5,128

A summary of stock option activity for the nine months ended September 30, 2023, is as follows:


						Weighted
				Weighted		Average		Average
				Average		Remaining		Intrinsic
	Number			Exercise		Contractual		Value (in
	of Options			Price		Term (Years)		thousands)
Outstanding as of December 31, 2022		365,216		$	184.45		5.8		20
Granted		4,000			3.82
Exercised		—			0.00
Cancelled or forfeited		(49,109	)		192.07
Outstanding as of September 30, 2023		320,107		$	181.02		4.9	$	—
Exercisable at September 30, 2023		262,967		$	210.43		4.3	$	—

As of September 30, 2023, the unrecognized share-based compensation expense, net of estimated forfeitures, related to all unvested time-based stock options held by the Company’s employees is $0.9 million and the weighted average period over which that expense is expected to be recognized is 3.3 years.

A summary of RSU activity for the nine months ended September 30, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		40,772		$	15.30
Granted		—			—
Vested		(37,675	)		15.11
Forfeited		(3,097	)		17.50
Unvested as of September 30, 2023		—		$	—

The Company has granted to certain employees stock options that vest upon the achievement of specified price targets of the Company’s share price for a period through December 31, 2024. Vesting is measured based upon the average closing price of the Company’s share price for any thirty consecutive trading days, subject to certain service requirements. Stock compensation cost is expensed on a straight-line basis over the derived service period for each stock price target within the award, ranging from approximately 4.0 to 4.6 years. The Company accelerates expense when a stock price target is achieved prior to the derived service period. As of September 30, 2023, there were 11,250 outstanding stock options containing market conditions with a weighted average exercise price of $40.20. As of September 30, 2023, there was a de minimis amount of unrecognized compensation costs related to stock options containing market conditions, which is expected to be recognized over a weighted-average period of 0.54 years.

License Agreement - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended
	Jun. 03, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 0	$ 0	$ 0	$ 297,000
Akebia Research License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up Front Payment Received	$ 3,000,000
Additional milestone cash payment	$ 12,000,000
Akbeia Supply Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 0	$ 0	$ 0	$ 300,000

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Share-based Compensation Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Number of Options
Outstanding at end of the year (in shares)	11,250
Weighted Average Exercise Price
Outstanding at end of the year (in dollars per share)	$ 40.2
Stock options
Number of Options
Outstanding at beginning of the year (in shares)	365,216
Granted (in shares)	4,000
Cancelled or forfeited (in shares)	(49,109)
Outstanding at end of the year (in shares)	320,107	365,216
Exercisable (in shares)	262,967
Weighted Average Exercise Price
Outstanding at beginning of the year (in dollars per share)	$ 184.45
Granted (in dollars per share)	3.82
Exercised (in dollars per share)	0
Cancelled or forfeited (in dollars per share)	192.07
Outstanding at end of the year (in dollars per share)	181.02	$ 184.45
Exercisable (in dollars per share)	$ 210.43
Weighted Average Remaining Contractual Term (years)
Weighted Average Remaining Contractual Term (years)	4 years 10 months 24 days	5 years 9 months 18 days
Weighted Average Remaining Contractual Term (years)	4 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding	$ 0	$ 20
Aggregate Intrinsic Value, Exercisable	$ 0

Share-based Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of share-based compensation expense


	Three Months Ended September 30,					Nine Months Ended September 30,
	2023			2022		2023		2022
Research and development	$	(19	)	$	773	$	391	$	2,396
General and administrative		178			889		573		2,732
	$	159		$	1,662	$	964	$	5,128

Schedule of stock option activity

A summary of stock option activity for the nine months ended September 30, 2023, is as follows:


						Weighted
				Weighted		Average		Average
				Average		Remaining		Intrinsic
	Number			Exercise		Contractual		Value (in
	of Options			Price		Term (Years)		thousands)
Outstanding as of December 31, 2022		365,216		$	184.45		5.8		20
Granted		4,000			3.82
Exercised		—			0.00
Cancelled or forfeited		(49,109	)		192.07
Outstanding as of September 30, 2023		320,107		$	181.02		4.9	$	—
Exercisable at September 30, 2023		262,967		$	210.43		4.3	$	—

Summary of RSU activity

A summary of RSU activity for the nine months ended September 30, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		40,772		$	15.30
Granted		—			—
Vested		(37,675	)		15.11
Forfeited		(3,097	)		17.50
Unvested as of September 30, 2023		—		$	—

Condensed Consolidated and Combined Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Preferred stock	Paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Beginning balance at Dec. 31, 2021	$ 48,246			$ 263,345	$ (215,076)	$ (23)
Beginning balance (in shares) at Dec. 31, 2021		2,170,509
Net loss	(12,978)				(12,978)
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		1,909
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	1,476			1,476
Share‑based compensation expense related to issuance of stock options to non-employees	291			291
Foreign currency translation adjustment gain (loss)	(1)					(1)
Ending balance at Mar. 31, 2022	37,034			265,112	(228,054)	(24)
Ending balance (in shares) at Mar. 31, 2022		2,172,418
Beginning balance at Dec. 31, 2021	48,246			263,345	(215,076)	(23)
Beginning balance (in shares) at Dec. 31, 2021		2,170,509
Net loss	(36,862)
Foreign currency translation adjustment gain (loss)	(5)
Ending balance at Sep. 30, 2022	16,524			268,490	(251,938)	(28)
Ending balance (in shares) at Sep. 30, 2022		2,174,709
Beginning balance at Mar. 31, 2022	37,034			265,112	(228,054)	(24)
Beginning balance (in shares) at Mar. 31, 2022		2,172,418
Net loss	(13,388)				(13,388)
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan	17			17
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		1,574
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	1,410			1,410
Share‑based compensation expense related to issuance of stock options to non-employees	289			289
Foreign currency translation adjustment gain (loss)	(1)					(1)
Ending balance at Jun. 30, 2022	25,361			266,828	(241,442)	(25)
Ending balance (in shares) at Jun. 30, 2022		2,173,992
Net loss	(10,496)				(10,496)
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		717
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	1,372			1,372
Share‑based compensation expense related to issuance of stock options to non-employees	290			290
Foreign currency translation adjustment gain (loss)	(3)					(3)
Ending balance at Sep. 30, 2022	16,524			268,490	(251,938)	(28)
Ending balance (in shares) at Sep. 30, 2022		2,174,709
Beginning balance at Dec. 31, 2022	$ 10,452			269,626	(259,154)	(20)
Beginning balance (in shares) at Dec. 31, 2022	2,175,936	2,175,936
Net loss	$ (6,954)				(6,954)
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		309
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	416			416
Share‑based compensation expense related to issuance of stock options to non-employees	10			10
Foreign currency translation adjustment gain (loss)	1					1
Ending balance at Mar. 31, 2023	3,925			270,052	(266,108)	(19)
Ending balance (in shares) at Mar. 31, 2023		2,176,245
Beginning balance at Dec. 31, 2022	$ 10,452			269,626	(259,154)	(20)
Beginning balance (in shares) at Dec. 31, 2022	2,175,936	2,175,936
Net loss	$ (3,569)
Foreign currency translation adjustment gain (loss)	2
Ending balance at Sep. 30, 2023	$ 12,873			275,614	(262,723)	(18)
Ending balance (in shares) at Sep. 30, 2023	2,445,096	2,445,096	351,037
Beginning balance at Mar. 31, 2023	$ 3,925			270,052	(266,108)	(19)
Beginning balance (in shares) at Mar. 31, 2023		2,176,245
Net loss	(4,181)				(4,181)
Issuance of common stock	1,953			1,953
Issuance of common stock (in shares)		225,000
Issuance of preferred shares value	3,047			3,047
Issuance of preferred shares ( in shares)			351,037
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan	24			24
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		6,618
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	373			373
Share‑based compensation expense related to issuance of stock options to non-employees	6			6
Foreign currency translation adjustment gain (loss)	3					3
Fractional shares issuance (in shares)		(67)
Ending balance at Jun. 30, 2023	5,150			275,455	(270,289)	(16)
Ending balance (in shares) at Jun. 30, 2023		2,407,796	351,037
Net loss	7,566				7,566
Issuance of common stock upon vesting of RSUs (in shares)		37,300
Share-based compensation expense related to issuance of stock options and RSUs to employees	154			154
Share‑based compensation expense related to issuance of stock options to non-employees	5			5
Foreign currency translation adjustment gain (loss)	(2)					(2)
Ending balance at Sep. 30, 2023	$ 12,873			$ 275,614	$ (262,723)	$ (18)
Ending balance (in shares) at Sep. 30, 2023	2,445,096	2,445,096	351,037

Gain (loss) per share - Additional Information (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted loss per share	351,037
Preferred stock, shares issued		0		0
Preferred stock, shares outstanding		0		0
Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted loss per share	0	0	351,037	0

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 9,108	$ 13,382
Accounts receivable	0	96
Prepaid expenses	726	805
Other current assets	30	537
Total current assets	9,864	14,820
Operating lease right-of-use asset	0	1,218
Other investment	5,350	0
Other assets	0	2,041
Total assets	15,214	18,079
Current liabilities:
Accounts payable	814	2,970
Accrued research and development costs	362	2,275
Accrued expenses and other current liabilities	1,165	2,382
Total current liabilities	2,341	7,627
Commitments and contingencies (Note 8)	0	0
Stockholders' equity
Preferred shares, no par value, 500,000 shares authorized and 351,037 series A convertible preferred stock issued and outstanding at September 30, 2023	0	0
Common stock, no par value, 20,000,000 shares authorized and 2,445,096 issued and outstanding September 30, 2023 and 20,000,000 shares authorized and 2,175,936 issued and outstanding at December 31, 2022	0	0
Paid-in capital	275,614	269,626
Accumulated deficit	(262,723)	(259,154)
Accumulated other comprehensive loss	(18)	(20)
Total stockholders' equity	12,873	10,452
Total liabilities and stockholders' equity	$ 15,214	$ 18,079

Discontinued Operations - Schedule of discontinued operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal of discontinued operations			$ 15,752	$ 0
Net gain (loss) from discontinued operations			15,752
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 50	$ 0	50	720
Research and development	691	5,668	4,439	22,240
General and administrative	1,637	421	4,033	1,419
Total cost and expenses	2,328	6,089	8,472	23,659
Loss from operations	(2,278)	(6,089)	(8,422)	(22,939)
Gain on disposal of discontinued operations	15,752	0	15,752	0
Net gain (loss) from discontinued operations	13,474	(6,089)	7,330	(22,939)
Grants \| Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 50	$ 0	$ 50	$ 720

Grant Revenue (Additional Information) (Details) - USD ($)	3 Months Ended		9 Months Ended		18 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenue Recognition and Deferred Revenue [Abstract]
PTC Grant Award					$ 2,000,000
Allowable Expenses on Grant Revenue	$ 100,000	$ 0	$ 100,000	$ 700,000

Gain (loss) per share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net loss from continuing operations	$ (5,908)			$ (4,407)			$ (10,899)	$ (13,923)
Net gain (loss) from discontinued operations	13,474			(6,089)			7,330	(22,939)
Net gain (loss)	$ 7,566	$ (4,181)	$ (6,954)	$ (10,496)	$ (13,388)	$ (12,978)	$ (3,569)	$ (36,862)
Denominator:
Weighted average shares used in calculating net gain (loss) per share - basic	2,435			2,174			2,299	2,173
Weighted average shares used in calculating net gain (loss) per share - diluted	2,786			2,174			2,299	2,173
Net gain (loss) per share - basic:
Net loss per share from continuing operations	$ (2.43)			$ (2.03)			$ (4.74)	$ (6.41)
Net gain (loss) per share from discontinued operations	5.53			(2.8)			3.19	(10.56)
Basic net gain (loss) per share	3.11			(4.83)			(1.55)	(16.96)
Net gain (loss) per share - diluted:
Net gain (loss) per share from discontinued operations	(2.12)			(2.03)			(4.74)	(6.41)
Net gain (loss) per share from discontinued operations	4.84			(2.8)			3.19	(10.56)
Diluted net gain (loss) per share	$ 2.72			$ (4.83)			$ (1.55)	$ (16.96)

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

3. Fair Value of Financial Instruments


	Fair Value Measurements as of September 30, 2023:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	8,237	$	—	$	—	$	8,237
Cash equivalents	$	8,237	$	—	$	—	$	8,237


	Fair Value Measurements as of December 31, 2022:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	12,357	$	—	$	—	$	12,357
Cash equivalents	$	12,357	$	—	$	—	$	12,357

During the nine months ended September 30, 2023 and 2022, there were no transfers between levels. The fair value of the Company’s cash equivalents, consisting of money market funds, is based on quoted market prices in active markets with no valuation adjustment.

The Company believes the carrying amounts of its prepaid expenses and other current assets, accounts receivable, accounts payable, and accrued expenses approximate their fair value due to the short-term nature of these amounts.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Gain (loss) per share - Schedule of Earnings Per Share Diluted By Common Class (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the calculation of diluted loss per share	351,037
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	$ 320,107	$ 423,290	$ 671,144	$ 423,290
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	320,107	420,666	320,107	420,666
Restricted Stock Units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	$ 0	$ 2,624	$ 0	$ 2,624
Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the calculation of diluted loss per share	0	0	351,037	0

Property and Equipment

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment

6. Property and Equipment

Property and equipment, net consisted of the following (in thousands):


	September 30,			December 31,
	2023			2022
Software	$	126		$	2,174
Computer equipment		—			7
Property and equipment, gross		126			2,181
Less: accumulated depreciation and amortization		(126	)		(2,181	)
Property and equipment, net	$	—		$	—

As of September 30, 2023, and December 31, 2022, the Company’s property and equipment was primarily located in Boston, Massachusetts.

During the three and nine months ended September 30, 2023, the Company did not record depreciation and amortization expenses. The Company recorded a de minimis amount and approximately $0.1 million of depreciation and amortization expenses for the three and nine months ended September 30, 2022.

Workforce Reduction (Tables)

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Schedule of accrued liabilities activity allocated to Cyclerion in connection with the reduction in workforce

The following table summarizes the accrued liabilities activity recorded in connection with the reduction in workforce for the nine months ended September 30, 2023 (in thousands):


	Amounts accrued at December 31, 2022			Charges			Amount paid		Adjustments		Amounts accrued at September 30, 2023
Workforce reduction	$	(809	)	$	(565	)	$	1,074	$	—	$	(300	)
Total	$	(809	)	$	(565	)	$	1,074	$	—	$	(300	)

Leases - Sublease as Lessor (Details) $ in Millions	3 Months Ended		9 Months Ended
Leases - Sublease as Lessor (Details) $ in Millions	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 15, 2020 ft²
Sublease as lessor
Rentable space terminated from lease agreement (in square feet) \| ft²					15,700
Sublease termination agreement estimated fair value of rooms	$ 1.5		$ 1.5
Sublease termination agreement estimated fair value of services	$ 2.9		2.9
Prepaid rooms balance reclassified from other assets			$ 1.4
Term of lease	8 years 10 months 17 days		8 years 10 months 17 days
License And Service
Sublease as lessor
lease expense	$ 0.1	$ 0.2	$ 0.1	$ 0.2

Defined Contribution Plan

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Defined Contribution Plan

12. Defined Contribution Plan

Subsequent to the Separation, the Company adopted a defined contribution 401(k) Savings Plan similar to the plan in place at Ironwood. The plan assets under the Ironwood defined contribution 401(k) Savings Plan were transferred to the Company's Plan.

Subject to certain IRS limits, eligible employees may elect to contribute from 1% to 100% of their compensation. The Company's contributions to the plan are at the sole discretion of the board of directors. Currently, the Company provides a matching contribution of 75% of the employee’s contributions, up to $6,000 annually.

Included in compensation expense is a de minimis amount and approximately $0.1 million related to the defined contribution 401(k) Savings Plan for the three and nine months ended September 30, 2023, respectively, and a de minimis amount, and approximately $0.2 million for the three and nine months ended September 30, 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
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-Section 55
-Paragraph 17
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (d)(i)
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-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 715
-SubTopic 20
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-Paragraph 2
-Publisher FASB
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Nature of Business (Details) $ / shares in Units, $ in Thousands			3 Months Ended			9 Months Ended		17 Months Ended	21 Months Ended
	Jul. 28, 2023 USD ($)	Sep. 03, 2020 USD ($)	Sep. 30, 2023 USD ($) $ / shares	Jun. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2023 USD ($) $ / shares	Sep. 30, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Sep. 30, 2023 USD ($) $ / shares	Mar. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 $ / shares	Jul. 24, 2020 USD ($)	Nov. 15, 2019 Employee
Nature of Business
Equity investment in cash										$ 5,000
Preferred stock, shares issued \| shares					0		0
Preferred stock, par value (in dollars per share) \| $ / shares			$ 0			$ 0			$ 0		$ 0
Cash consideration transferrred	$ 8,000
Operating Expenses	$ 2,400		$ 6,015		$ 4,518	$ 11,156	$ 14,382
Issuance of common stock				$ 1,953
Cash commission of gross proceeds of sales of common stock, percentage		3.00%
Proceeds from stock purchase agreement						5,000	$ 0
Common stock issued or sold under the ATM Offering								$ 3,353,059	$ 0
IPO
Nature of Business
Maximum amount of Aggregate initial offering price												$ 150,000
ATM Offering \| Jefferies LLC
Nature of Business
Proceeds from stock purchase agreement								$ 12,500
ATM Offering \| Maximum \| Jefferies LLC
Nature of Business
Issuance of common stock		$ 50,000
Cyclerion Securities Corporation
Nature of Business
Number of employees \| Employee													0
Commercialization milestone payments						$ 585,000
Tisento Therapeutics Holdings Inc [Member]
Nature of Business
Outstanding equity securities	10.00%
Common stock
Nature of Business
Common stock shares issued \| shares										225,000
Issuance of common stock (in shares) \| shares				225,000
Series A preferred stock
Nature of Business
Preferred stock, shares issued \| shares										351,037
Preferred stock, par value (in dollars per share) \| $ / shares										$ 8.68

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Accrued Liabilities and Other Liabilities [Abstract]

Schedule of accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	September 30,		December 31,
	2023		2022
Accrued incentive compensation	$	—	$	238
Salaries		14		246
Accrued vacation		17		186
Professional fees		676		835
Accrued severance and benefit costs		300		809
Other		158		68
Accrued expenses and other current liabilities	$	1,165	$	2,382

Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 28, 2023	May 11, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration on acquisition transferred	$ 8,000
Research and development expense			$ 580	$ 1,414	$ 1,491	$ 4,803
Closing costs associated with sale of Program Assets			1,300		1,300
Transaction costs associated with sale of Program Assets			$ 200		$ 900
TisentoT herapeutics Holdings Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity securities, percentage	10.00%
TisentoT herapeutics Holdings Inc [Member] \| Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration on acquisition transferred		$ 8,000
Research and development expense		$ 2,400
Equity securities, percentage		10.00%

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	500,000
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	2,445,096	2,175,936
Common stock, shares outstanding	2,445,096	2,175,936
SeriesA Convertible Preferred Stock [Member]
Preferred stock, shares issued	351,037
Preferred stock, shares outstanding	351,037

Discontinued Operations (Tables)

9 Months Ended

Sep. 30, 2023

Discontinued Operations and Disposal Groups [Abstract]

Schedule of discontinued operations

The following table presents the results of the discontinued operations for the three and nine months ended September 30, 2023 and 2022 (in thousands):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Revenues:
Revenue from grants	$	50		$	—		$	50		$	720
Total revenues		50			—			50			720
Cost and expenses:
Research and development		691			5,668			4,439			22,240
General and administrative		1,637			421			4,033			1,419
Total cost and expenses		2,328			6,089			8,472			23,659
Loss from operations		(2,278	)		(6,089	)		(8,422	)		(22,939	)
Gain on disposal of discontinued operations		15,752			—			15,752			—
Net gain (loss) from discontinued operations	$	13,474		$	(6,089	)	$	7,330		$	(22,939	)

The following table summarizes the carrying amounts of major classes of assets and liabilities of discontinued operations as of December 31, 2022 (in thousands).


	December 31, 2022
Prepaid expenses	$	3
Other current assets		20
Total current assets of discontinued operations		23
Total assets of discontinued operations		23

Accounts payable		2,389
Accrued research and development costs		2,233
Accrued expenses and other current liabilities		155
Total current liabilities of discontinued operations		4,777
Total liabilities of discontinued operations		4,777
Net liabilities of discontinued operations	$	(4,754	)

The following table presents the significant non-cash item for the discontinued operations that are included in the accompanying unaudited condensed consolidated statements of cash flows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Cash flows from operating activities:
Share-based compensation expense	$	—	$	306	$	505	$	937

Schedule of transaction consideration received from the sale of the Program Assets

The transaction consideration received from the sale of the Program Assets were as follows (in thousands):


	Amount
Closing payment	$	8,000
Expense reimbursement		2,402
Investment in Tisento Parent		5,350
Gross transaction consideration from the sale		15,752
Net assets sold		—
Gain on disposal of discontinued operations	$	15,752

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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+ Details

Discontinued Operations - Schedule of discontinued operations carrying amounts of major classes of assets and liabilities (Details) - Discontinued Operations $ in Thousands	Dec. 31, 2022 USD ($)
Assets of discontinued operations, Current
Prepaid expenses	$ 3
Other current assets	20
Total current assets of discontinued operations	23
Total assets of discontinued operations	23
Current liabilities of discontinued operations
Accounts payable	2,389
Accrued research and development costs	2,233
Accrued expenses and other current liabilities	155
Total current liabilities of discontinued operations	4,777
Total liabilities of discontinued operations	4,777
Net liabilities of discontinued operations	$ (4,754)

Grant Revenue

9 Months Ended

Sep. 30, 2023

Disaggregation of Revenue [Line Items]

Grant Revenue

15. Grant Revenue

In August 2021, the Company was approved to receive funding from Alzheimer’s Association’s Part the Cloud-Gates Partnership Grant Program (the "PTC Grant”) for the Phase 2 study of CNS sGC stimulation in AD with vascular features. The granting period was July 1, 2021, to December 31, 2022, and the Company receive an award of $2 million. The Company determined that this transaction is non-reciprocal as there is not considered to be a commensurate value exchanged with the Alzheimer's Association as the funding provider. Where commensurate value is not exchanged for goods and services provided, a recipient assesses whether the grant is conditional or unconditional. The Company considered all conditions and barriers associated with this grant and determined the grant is conditional and revenue will be recognized upon achieving certain milestones and incurring internal costs specifically covered by this grant. Under ASC 958-605, revenues were recognized as the Company incurred expenses related to the PTC Grant.

The Company incurred approximately $0.1 million of expenses associated with the grant for the three and nine months ended September 30, 2023, compared to approximately $0.7 million of expenses associated with the grant for the nine months ended September 30, 2022. There is no cost incurred associated with the grant during the three months ended September 30, 2022.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

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-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Share-based Compensation Plans (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) TradingDay $ / shares shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 $ / shares shares
Share-based Compensation Plans
Share-based compensation \| $	$ 159	$ 1,662	$ 964	$ 5,128
Expected period to recognize the expense			6 months 14 days
outstanding stock options \| shares	11,250		11,250
weighted average exercise price \| $ / shares	$ 40.2		$ 40.2
Stock options
Share-based Compensation Plans
Unrecognized share-based compensation expense \| $	$ 900		$ 900
Expected period to recognize the expense			3 years 3 months 18 days
outstanding stock options \| shares	320,107		320,107		365,216
weighted average exercise price \| $ / shares	$ 181.02		$ 181.02		$ 184.45
Performance stock options
Share-based Compensation Plans
Threshold consecutive trading days, used as a base for measurement of vesting of stock awards \| TradingDay			30
Performance stock options \| Minimum
Share-based Compensation Plans
Expected option term (in years)			4 years
Performance stock options \| Maximum
Share-based Compensation Plans
Expected option term (in years)			4 years 7 months 6 days

Property and Equipment (Tables)

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Schedule of property and equipment, net

Property and equipment, net consisted of the following (in thousands):


	September 30,			December 31,
	2023			2022
Software	$	126		$	2,174
Computer equipment		—			7
Property and equipment, gross		126			2,181
Less: accumulated depreciation and amortization		(126	)		(2,181	)
Property and equipment, net	$	—		$	—

Leases

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Leases

9. Leases

In May 2021 the Company signed a 12-month membership agreement to lease space with WeWork at 501 Boylston Street, Boston, Massachusetts, commencing on August 1, 2021. The agreement was extended for six months on August 1, 2022. The 12-month agreements and 6-month extension are accounted for as short-term leases. The lease agreement was terminated during the three months ended March 31, 2023. The Company recorded a de minimis amount of lease expense associated with the membership agreement during the nine months ended September 30, 2023.

On September 15, 2020, the Company entered into a Sublease Termination Agreement (the "Sublease Termination Agreement") to terminate its sublease of 15,700 rentable square feet of its leased premises at 301 Binney Street, Cambridge, Massachusetts. Under the terms of the Sublease Termination Agreement, the subtenant was relieved of its obligation to provide future cash rental payments to the Company. The agreements requiring the former subtenant to provide licensed rooms and services to the Company free of charge through the original sublease term survived the sublease termination. The Company gained access to the licensed rooms and services beginning in the third quarter of 2021. The letter of credit security deposit related to the sublease was released.

The Company determined that the Sublease Termination Agreement constituted a non-monetary exchange under ASC 845 Nonmonetary Transactions (“ASC 845”) where, in return for the free rooms and the services, the Company agreed to terminate its rights and obligations under the sublease agreement. In accordance with ASC 845, the Company determined that the accounting for the transaction should be based on the fair value of assets or services involved. The Company estimated the fair value of the rooms and services to be approximately $1.5 million and $2.9 million, respectively.

The Company determined that the licensed rooms represent a lease under ASC Topic 842 Leases. The Company obtained control of the rooms in the third quarter of 2021 and the prepaid rooms balance of approximately $1.4 million was reclassified from other assets to a ROU asset. The related lease expense is recognized on a straight-line basis over the lease term of 8.88 years. The Company recorded a de minimis amount, and $0.1 million of lease expense during the three and nine months ended September 30, 2023 and 2022, respectively. The Company determined that the licensed services represent a non-lease component, which is recognized separately from the lease component for this asset class. The expense related to the licensed services is recognized on a straight-line basis over the period the services are received. The Company recorded a $0.1 million and $0.2 million for the three and nine months ended September 30, 2023 and 2022, respectively. Both the lease expense and services expense are recognized as a component of research and development costs in the condensed consolidated statements of operations and comprehensive loss.

After the closing of the Asset Purchase Agreement, the Company had no plans in the foreseeable future to use the licensed rooms and the Company is restricted from subleasing the rooms. In August 2023, the ROU asset and other assets were fully impaired and the Company recognized a $3.3 million impairment loss during the three and nine months ended September 30, 2023.

License Agreement

9 Months Ended

Sep. 30, 2023

License Agreement [Abstract]

License Agreement

14. License Agreement

Akebia License Agreement

On June 3, 2021, the Company and Akebia entered into a License Agreement (the “Akebia License Agreement”) relating to the exclusive worldwide license by the Company to Akebia of our rights to the development, manufacture, medical affairs and commercialization of pharmaceutical products containing the pharmaceutical compound known as praliciguat and other related products and forms thereof enumerated in the License Agreement (collectively, the “Products”). Pursuant to the Akebia License Agreement, Akebia will be responsible for all future research, development, regulatory, and commercialization activities for the Products.

Akebia paid a $3.0 million up-front payment to the Company upon signing of the Akebia License Agreement and the Company is eligible to receive additional milestone cash payments of up to $12.0 million upon initiation of a Phase 2 clinical trial. Further milestone cash payments by Akebia are scheduled in the Akebia License Agreement based on the initiation of Phase 3 clinical trials in the U.S. for Products for first and second indication, for FDA approvals, for approvals in certain other major markets, and for certain sales milestones. In addition to these cash milestone payments, Akebia will pay the Company tiered royalty payments on net sales in certain major markets at percentages ranging from the mid-single digits to the high-teens, subject to certain reductions and offsets.

Pursuant to the Akebia License Agreement, the Company determined the Akebia License Agreement represents a service arrangement under the scope of ASC 606. Given the reversion of the rights under the Akebia License Agreement represents a penalty in substance for a termination by Akebia, the contract term would be the stated term of the Akebia License Agreement.

The Company determined that the grant of license to our patents and trademarks, know how transfer, the assignment of regulatory submissions and trademarks and additional knowledge transfer assistance obligations represent a single promise and performance obligation to be transferred to Akebia over time due to the nature of the

promises in the contract. The provision of development materials on hand was identified as a separate performance obligation. However, it is immaterial in the context of the contract as the development materials are low value and do not have an alternative use to the Company.

The consideration related to sales-based milestone payments, including royalties, will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license. The Company will re-evaluate the probability of achievement of the milestones and any related constraints each reporting period.

Akebia Supply Agreement

On August 3, 2021, the Company and Akebia entered into a Supply Agreement (the “Supply Agreement”) relating to the manufacturing by the Company of the Initial Supply of the Drug Product and placebo ("Initial Supply") for Akebia's use pursuant to the Akebia License Agreement. Akebia will pay the Company for the manufacturing costs at mutually agreed upon rates.

The Company determined the Supply Agreement has stand-alone value under the scope of ASC 606 and should not be combined with the Akebia License Agreement. Given that the Supply Agreement can be terminated at any time without cause with 30 days' notice, the Company deemed the Supply Agreement to be a month-to-month contract. The manufacturing of the Initial Supply by the Company represents a single performance obligation and consideration related to the manufacturing costs will be recognized over time as costs are incurred. The Company did not record any revenue for the three months ended September 30, 2023 and 2022 and the nine months ended September 30, 2023. The Company recorded $0.3 million as revenue from the Supply Agreement in the nine months ended September 30, 2022.

Share-based Compensation Plans - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation	$ 159	$ 1,662	$ 964	$ 5,128
Research and development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation	(19)	773	391	2,396
General and administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation	$ 178	$ 889	$ 573	$ 2,732

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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-Topic 718
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (c)(1)(i)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Discontinued Operations

9 Months Ended

Sep. 30, 2023

Discontinued Operations and Disposal Groups [Abstract]

Discontinued Operations

4. Discontinued Operations

On May 11, 2023, the Company entered into the Purchase Agreement with Tisento for Tisento’s acquisition of substantially all of the assets comprising the Company’s zagociguat and CY3018 programs, in exchange for consideration at closing of $8.0 million, the reimbursement of employee expenses or R&D expenses of $2.4 million that Tisento reimbursed the Company for upon closing, and 10% of the issued and outstanding shares of Tisento Parent (Note 5). Upon closing of the transaction, the Company transferred certain fully depreciated software included within property and equipment to Tisento.

The carrying value of the disposal group was lower than its fair value, less costs to sell, and accordingly, a gain on disposal was recorded during the three and nine months ended September 30, 2023. The operations of the Program Assets are presented as discontinued for all periods presented. The transaction closed on July 28, 2023.

The following table presents the results of the discontinued operations for the three and nine months ended September 30, 2023 and 2022 (in thousands):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Revenues:
Revenue from grants	$	50		$	—		$	50		$	720
Total revenues		50			—			50			720
Cost and expenses:
Research and development		691			5,668			4,439			22,240
General and administrative		1,637			421			4,033			1,419
Total cost and expenses		2,328			6,089			8,472			23,659
Loss from operations		(2,278	)		(6,089	)		(8,422	)		(22,939	)
Gain on disposal of discontinued operations		15,752			—			15,752			—
Net gain (loss) from discontinued operations	$	13,474		$	(6,089	)	$	7,330		$	(22,939	)

The following table summarizes the carrying amounts of major classes of assets and liabilities of discontinued operations as of December 31, 2022 (in thousands).


	December 31, 2022
Prepaid expenses	$	3
Other current assets		20
Total current assets of discontinued operations		23
Total assets of discontinued operations		23

Accounts payable		2,389
Accrued research and development costs		2,233
Accrued expenses and other current liabilities		155
Total current liabilities of discontinued operations		4,777
Total liabilities of discontinued operations		4,777
Net liabilities of discontinued operations	$	(4,754	)


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Cash flows from operating activities:
Share-based compensation expense	$	—	$	306	$	505	$	937

The transaction consideration received from the sale of the Program Assets were as follows (in thousands):


	Amount
Closing payment	$	8,000
Expense reimbursement		2,402
Investment in Tisento Parent		5,350
Gross transaction consideration from the sale		15,752
Net assets sold		—
Gain on disposal of discontinued operations	$	15,752

During the three and nine months ended September 30, 2023, the Company incurred $1.3 million in closing costs associated with the sale of the Program Assets. The Company also incurred $0.2 and $0.9 million in transaction costs associated with the sale of the Program Assets during the three and nine months ended September 30, 2023, respectively. All of the closing and transaction costs were recognized as part of discontinued operations - general and administrative.

Other Investment - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 28, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investment Holdings, Other than Securities [Line Items]
Cash consideration transferrred	$ 8,000
Operating expenses	$ 2,400	$ 6,015	$ 4,518	$ 11,156	$ 14,382
Impairment loss on other investments				$ 0
TisentoT herapeutics Holdings Inc [Member]
Investment Holdings, Other than Securities [Line Items]
Outstanding equity securities	10.00%
Fair value of outstanding equity securities	$ 5,300
Treasury rate [Member]
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	4.01%
Maximum [Member] \| Weighted average cost of capital [Member]
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	23.00%
Maximum [Member] \| Terminal decline rate [Member]
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	75.00%
Minimum [Member] \| Weighted average cost of capital [Member]
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	21.00%
Minimum [Member] \| Terminal decline rate [Member]
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	25.00%

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Nov. 09, 2023
Cover [Abstract]
Entity Registrant Name	CYCLERION THERAPEUTICS, INC.
Document Type	10-Q
Document Period End Date	Sep. 30, 2023
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		2,445,096
Entity Central Index Key	0001755237
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Entity Tax Identification Number	83-1895370
Entity File Number	001-38787
Entity Incorporation, State or Country Code	MA
Entity Address, Address Line One	245 First Street
Entity Address, Address Line Two	18th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	327-8778
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	CYCN
Security Exchange Name	NASDAQ

Gain (loss) per share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Schedule of basic and diluted earnings per share

Basic and diluted net gain (loss) per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Numerator:
Net loss from continuing operations (in thousands)	$	(5,908	)	$	(4,407	)	$	(10,899	)	$	(13,923	)
Net gain (loss) from discontinued operations (in thousands)		13,474			(6,089	)		7,330			(22,939	)
Total net gain (loss) (in thousands)		7,566			(10,496	)		(3,569	)		(36,862	)

Denominator:
Weighted average shares used in calculating net gain (loss) per share — basic (in thousands)		2,435			2,174			2,299			2,173
Weighted average shares used in calculating net gain (loss) per share — diluted (in thousands)		2,786			2,174			2,299			2,173

Net gain (loss) per share — basic
Net loss per share from continuing operations	$	(2.43	)	$	(2.03	)	$	(4.74	)	$	(6.41	)
Net gain (loss) per share from discontinued operations		5.53			(2.80	)		3.19			(10.56	)
Total gain (loss) per share	$	3.11		$	(4.83	)	$	(1.55	)	$	(16.96	)

Net gain (loss) per share — diluted
Net loss per share from continuing operations	$	(2.12	)	$	(2.03	)	$	(4.74	)	$	(6.41	)
Net gain (loss) per share from discontinued operations		4.84			(2.80	)		3.19			(10.56	)
Total gain (loss) per share	$	2.72		$	(4.83	)	$	(1.55	)	$	(16.96	)

Schedule of earnings per share diluted by common class

The following table sets forth potential shares that were considered anti-dilutive for the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Preferred Stock		—		—		351,037		—
Stock Options		320,107		420,666		320,107		420,666
RSUs		—		2,624		—		2,624
		320,107		423,290		671,144		423,290

Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Property and Equipment
Property and equipment. gross	$ 126		$ 126		$ 2,181
Less: accumulated depreciation and amortization	(126)		(126)		(2,181)
Property and equipment, net	0		0		0
Depreciation and amortization			0	$ 65
Property and Equipment
Property and Equipment
Depreciation and amortization	0	$ 100	0	$ 100
Software
Property and Equipment
Property and equipment. gross	126		126		2,174
Computer and office equipment
Property and Equipment
Property and equipment. gross	$ 0		$ 0		$ 7

Workforce Reduction

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Workforce Reduction

13. Workforce Reduction

On October 6, 2022, the Company began a reduction of its current workforce by thirteen (13) full-time employees to align its resources with its current priorities of focusing on a mitochondrial disease-focused strategy. The workforce reduction was completed in the fourth quarter of 2022.

The Company recorded total costs related to the 2022 Workforce Reduction of approximately $1.3 million, including a de minimis amount of stock-based compensation from the modification of certain share-based equity awards.

The following table summarizes the accrued liabilities activity recorded in connection with the reduction in workforce for the nine months ended September 30, 2023 (in thousands):


	Amounts accrued at December 31, 2022			Charges			Amount paid		Adjustments		Amounts accrued at September 30, 2023
Workforce reduction	$	(809	)	$	(565	)	$	1,074	$	—	$	(300	)
Total	$	(809	)	$	(565	)	$	1,074	$	—	$	(300	)

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements and the related disclosures are unaudited and have been prepared in accordance with accounting principles generally accepted in the U.S. Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022, which was filed with the Securities and Exchange Commission on March 22, 2023. In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all normal recurring adjustments considered necessary for a fair presentation of the Company’s financial position and the results of its operations for the interim periods presented. The results of operations for the three and nine months ended September 30, 2023 and 2022 are not necessarily indicative of the results that may be expected for the full year or any other subsequent interim period. The condensed consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries, Cyclerion GmbH, and Cyclerion Securities Corporation. All significant intercompany accounts and transactions have been eliminated in the preparation of the accompanying condensed consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with U.S. generally accepted accounting principles ("GAAP") requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the amounts of expenses during the reported periods. On an ongoing basis, the Company’s management evaluates its estimates, judgments, and methodologies. Significant estimates and assumptions in the consolidated financial statements include those related to revenue, fair value determination of other investment, impairment of long-lived assets, valuation procedures for right-of-use ("ROU") assets and operating lease liabilities, income taxes, including the valuation allowance for deferred tax assets, research and development expenses, contingencies, share-based compensation and going concern. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ materially from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known.
New Accounting Pronouncements	New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Except as discussed elsewhere in the notes to the consolidated financial statements, the Company did not adopt any new accounting pronouncements during the nine months ended September 30, 2023 that had a material effect on its condensed consolidated financial statements. In June 2016 the FASB issued ASU 2016-13, Financial Instruments-Credit Losses. This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. As a smaller reporting company, ASU 2016-13 became effective for the Company for fiscal years beginning after December 15, 2022. The Company adopted ASU 2016-13 in the first quarter of 2023, and the adoption of this standard did not have any impact on the Company's financial position or results of operations. No other accounting standards known by the Company to be applicable to it that have been issued by the FASB or other standard-setting bodies and that do not require adoption until a future date are expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Leases - Summary (Details) $ in Millions	3 Months Ended		9 Months Ended
Leases - Summary (Details) $ in Millions	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Aug. 01, 2022	May 31, 2021	Sep. 15, 2020 ft²
Leases
Term of lease	8 years 10 months 17 days		8 years 10 months 17 days
Rentable space terminated from lease agreement (in square feet) \| ft²							15,700
Impairment loss	$ 3.3		$ 3.3
License And Service
Leases
lease expense	0.1	$ 0.2	0.1	$ 0.2
Licensed Room
Leases
lease expense	$ 0.1	$ 0.1	$ 0.1	$ 0.1
Wework
Leases
Term of lease					12 months	12 months
Renewal term					6 months

Defined Contribution Plan (Details) - USD ($)	3 Months Ended		9 Months Ended
Defined Contribution Plan (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Contribution Plan
401 (k) Savings Plan			us-gaap:QualifiedPlanMember
Matching contribution (as a percent of employee's contributions)			75.00%
Maximum amount of employer matching contribution			$ 6,000
Compensation expense related to the defined contribution 401(k) Savings Plan	$ 100,000	$ 200,000	$ 100,000	$ 200,000
Minimum
Defined Contribution Plan
Percent of compensation eligible employees may elect to contribute			1.00%
Maximum
Defined Contribution Plan
Percent of compensation eligible employees may elect to contribute			100.00%

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues:
Revenue from development agreement	$ 0	$ 0	$ 0	$ 297
Total revenues	0	0	0	297
Cost and expenses:
Research and development	580	1,414	1,491	4,803
General and administrative	2,131	3,104	6,361	9,579
Impairment Loss	3,304	0	3,304	0
Total cost and expenses	6,015	4,518	11,156	14,382
Loss from operations	(6,015)	(4,518)	(11,156)	(14,085)
Interest and other income, net	107	111	257	162
Net loss from continuing operations	(5,908)	(4,407)	(10,899)	(13,923)
Discontinued operations:
Gain (loss) from discontinued operations	13,474	(6,089)	7,330	(22,939)
Net gain (loss)	$ 7,566	$ (10,496)	$ (3,569)	$ (36,862)
Net gain (loss) per share - basic:
Net loss per share from continuing operations - basic	$ (2.43)	$ (2.03)	$ (4.74)	$ (6.41)
Net gain (loss) per share from discontinued operations - basic	5.53	(2.8)	3.19	(10.56)
Basic net gain (loss) per share	3.11	(4.83)	(1.55)	(16.96)
Net gain (loss) per share - diluted:
Net loss per share from continuing operations - diluted	(2.12)	(2.03)	(4.74)	(6.41)
Net gain (loss) per share from discontinued operations - diluted	4.84	(2.8)	3.19	(10.56)
Diluted net gain (loss) per share	$ 2.72	$ (4.83)	$ (1.55)	$ (16.96)
Weighted average shares used in calculating:
Basic shares	2,435	2,174	2,299	2,173
Diluted shares	2,786	2,174	2,299	2,173
Other comprehensive loss:
Net gain (loss)	$ 7,566	$ (10,496)	$ (3,569)	$ (36,862)
Other comprehensive loss:
Foreign currency translation adjustment gain (loss)	(2)	(3)	2	(5)
Comprehensive gain (loss)	$ 7,564	$ (10,499)	$ (3,567)	$ (36,867)