Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation – Condensed Consolidated Financial Information - The accompanying condensed consolidated financial statements and related notes have been prepared in accordance with accounting principles generally accepted in the US (US GAAP) for financial information, and in accordance with the rules and regulations of the US Securities and Exchange Commission (SEC) with respect to Form 10-Q and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The condensed consolidated financial statements furnished reflect all normal adjustments, which are, in the opinion of management, necessary for a fair statement of results for the interim periods presented. Interim results are not necessarily indicative of the results for the full year. These condensed consolidated financial statements should be read in conjunction with the audited financial statements of the Company as of December 31, 2024 and for the year then ended, including the notes thereto contained in the Form 10-K filed with the SEC on March 21, 2025.

Segment Reporting, Policy [Policy Text Block]

Segment Information - Management has determined that the Company operates in one reportable segment, which is the development and commercialization of drug products. The Company's chief operating decision maker (CODM) is its Chief Executive Officer and Chairman, who reviews financial information presented on a consolidated basis. The CODM primarily uses consolidated net loss, which is also reported on the Consolidated Statements of Operations and Comprehensive Loss as net loss, to assess financial performance and allocate resources. These financial metrics are used by the CODM to make key operating decisions, such as the assessment of segment performance and allocation of resources. The significant expense categories within net loss from operations that the CODM regularly reviews are research and development expenses and general and administrative expenses. The significant expense categories and subcategories are reported on the Consolidated Statements of Operations and Comprehensive Loss. Other expenses included in the Company’s net loss include change in fair value of warrant liabilities, other income (expense), interest income, net, and any additional non-operating expenses that are reported on the Consolidated Statements of Operations and Comprehensive Loss.

Going Concern Policy [Policy Text Block]

Going Concern and Liquidity - These condensed consolidated financial statements have been prepared on a going concern basis, which assumes the Company will continue to realize its assets and discharge its liabilities in the normal course of business. The continuation of the Company as a going concern is dependent upon the ability of the Company to obtain necessary equity financing to continue operations and the attainment of profitable operations. As of September 30, 2025, the Company had an accumulated deficit of $221.6 million since inception and had not yet generated any revenues from operations. Additionally, management anticipates that its cash on hand of $6.7 million as of September 30, 2025 is not sufficient to fund its planned operations for a period of at least one year from when these consolidated financial statements are issued. These factors raise substantial doubt regarding the Company's ability to continue as a going concern. These unaudited condensed consolidated financial statements do not include any adjustments to the recoverability and classification of recorded asset amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. The Company intends to seek additional funding through one or more of the following: a combination of equity offerings, debt financings, government or other third-party funding, commercialization, marketing and distribution arrangements, other collaborations, strategic alliances and licensing arrangements and delay planned cash outlays or a combination thereof. There can be no assurance that such events or a combination thereof can be achieved.

In March 2022, the Company received a subpoena from the SEC requesting information and documents, including materials related to certain individuals (none of which are the Company's officers or directors) and entities, and materials related to the development of and statements regarding the Company's drug candidate for the treatment of COVID-19. The Company has received, and expects to continue to receive, periodic further requests from the SEC staff with respect to this matter. The Company is not aware of the specific nature of the underlying investigation by the SEC, and to the extent that this investigation relates to prior public disclosures that it has made, the Company believes in the accuracy and adequacy of such prior disclosures. The correspondence from the SEC transmitting the subpoena to the Company states that the SEC is trying to determine whether there have been any violations of federal securities laws, but that its investigation does not mean that the SEC has concluded that anyone has violated the law or that the SEC has a negative opinion of any person, entity, or security. The Company cannot predict when this matter will be resolved or what, if any, action the SEC may take following the conclusion of the investigation. The Company's expenses for the three and nine months ended September 30, 2025, were not material. The Company expensed approximately $0.1 million and $0.2 million in related general and administrative fees and expenses for the three and nine months ended September 30, 2024, respectively. The Company has not hit the retention limits, so no reimbursement is expected. Accordingly, the Company has not recorded any provision for insurance reimbursement as of September 30, 2025.

Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]

Intangible Assets – Intangible assets with finite lives are amortized using the straight-line method over their estimated period of benefit. Acquired intangible assets identified as in-process research and development (IPR&D) assets, are considered indefinite lived until the completion or abandonment of the associated research and development efforts. If the associated research and development effort is abandoned, the related IPR&D assets will be written off and the Company will record a noncash impairment loss on its statements of operations. For those compounds that reach commercialization, the IPR&D assets will be amortized over their estimated useful lives. Intangible assets are tested for impairment on an annual basis, which was completed as of September 30, 2025, and between annual tests if indicators of potential impairment exist, using a fair-value-based approach. The Company evaluates the recoverability of intangible assets periodically and takes into account events or circumstances that warrant revised estimates of useful lives or that indicate that impairment exists. No impairments of intangible assets have been identified during any of the periods presented.

Other Non-Current Assets [Policy Text Block]

Other Non-Current Assets - The Company provided a cash deposit on the MB-108 trial that is expected to be held as a prepayment until the end of the study in 2029.

Earnings Per Share, Policy [Policy Text Block]

Loss Per Common Share - Basic net loss per common share is computed by dividing net loss available to common shareholders by the weighted-average number of common shares outstanding during the period. For purposes of this calculation, options to purchase common stock, restricted stock units subject to vesting and warrants to purchase common stock are considered to be common stock equivalents. Diluted net loss per common share is determined using the weighted-average number of common shares outstanding during the period, adjusted for the dilutive effect of common stock equivalents. In periods when losses are reported, the weighted-average number of common shares outstanding excludes common stock equivalents, because their inclusion would be anti-dilutive. For the three months ended September 30, 2025 and 2024, approximately 85.7 million and 4.8 million, respectively, of potentially dilutive shares were excluded from the computation of diluted earnings per share due to their anti-dilutive effect. For the nine months ended September 30, 2025 and 2024, approximately 41.7 million and 2.7 million, respectively, of potentially dilutive shares were excluded from the computation of diluted earnings per share due to their anti-dilutive effect.

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements - In November 2024 and January 2025, FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires disclosure in the notes to the financial statements of specified information about certain costs and expenses. The amendments are effective for fiscal years beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The amendments should be applied either prospectively to financial statements issued for reporting periods after the effective date of this ASU or retrospectively to any or all prior periods presented in the financial statements. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements and related disclosures, but expects additional disclosures upon adoption.

In December 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. ASU 2023-09 improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance is effective for the annual periods beginning after the year ended December 31, 2024. There was no material impact upon adoption of ASU 2023-09 on the Company's interim disclosures.

There are no other effective pronouncements, or pronouncements issued but not yet effective, if adopted, that would have a material effect on the accompanying financial statements.

Change in Accounting Policy - During the quarter ended September 30, 2025, the Company changed its accounting policy related to the classification of certain outstanding warrants. Prior to the change in accounting policy, the Company's policy was to account for warrants with a certain contingent settlement provision as liability warrants, initially measuring them at fair value on the date of issuance. The warrants were previously remeasured at fair value at the end of each reporting period, with the related liability reflected on the Company's balance sheet. The changes in fair value during each previous reporting period were recognized as a gain (loss) from change in fair value of warrant liability in the Company's condensed consolidated statement of operations. The Company has changed its policy and warrants that contain this certain contingent settlement provision will now be accounted as equity under ASC 815-40-15-7C through 15-7F and ASC 505. The Company concluded that accounting for its warrants as equity instruments is preferable under ASC 250, as equity classification better reflects the economic substance of the arrangement and enhances the clarity and consistency of the Company's financial reporting. As a result of this change in accounting policy, all warrants issued prior to 2025, and certain warrants issued in 2025, that were previously accounted for as liability awards due to the certain contingent settlement provision will now meet the equity classification criteria under ASC 815-40 and will be classified as equity instruments. The effects of the change in accounting policy from warrant liabilities to equity have been retrospectively applied to all periods presented in these condensed consolidated financial statements. Certain warrants issued in 2025 will continue to be classified as a liability as these warrants contain features other than the contingent settlement provision that cause liability classification. See also Note 4 - Warrants and Equity.

As a result of the change in accounting policy, the Company adjusted accumulated deficit, and additional paid-in capital to reverse previously recorded mark-to-market fair value changes of the liability-classified warrants. Warrants classified as liability warrants were adjusted retrospectively from January 2017 to June 2025, and beginning balances have been adjusted for the policy change to equity warrant classifications. Accumulated deficit as of January 1, 2024, changed from $131.6 million, as reported under the liability classification, to $146.4 million under the equity classification.

The following financial statement line items were impacted by the change in accounting policy, as shown in the tables below (in thousands, except per common share data):

	*September 30, 2025*									*December 31, 2024*
				*As Reported*			*Effect of*			*As Reported*			*As Adjusted*			*Effect of*
	*Under Old Policy*			*Under New Policy*			*Change*			*Under Old Policy*			*Under New Policy*			*Change*
Condensed Consolidated Balance Sheets
Warrant liability - long-term	$	48,660		$	41,333		$	(7,327	)	$	5,229		$	—		$	(5,229	)
Total liabilities		54,600			47,273			(7,327	)		10,946			5,717			(5,229	)
Additional paid-in capital		162,337			194,631			32,294			159,384			183,690			24,306
Accumulated deficit		(196,589	)		(221,556	)		(24,967	)		(153,367	)		(172,444	)		(19,077	)
Total stockholders' equity (deficit)		(34,247	)		(26,920	)		7,327			5,979			11,208			5,229
Total liabilities and stockholders' equity (deficit)		20,353			20,353			—			16,925			16,925			—

	*March 31, 2025*									*June 30, 2025*
	*As Reported*			*As Adjusted*			*Effect of*			*As Reported*			*As Adjusted*			*Effect of*
	*Under Old Policy*			*Under New Policy*			*Change*			*Under Old Policy*			*Under New Policy*			*Change*
Condensed Consolidated Balance Sheets
Warrant liability - long-term	$	13,749		$	—		$	(13,749	)	$	20,553		$	16,973		$	(3,580	)
Total liabilities		20,971			7,222			(13,749	)		28,758			25,178			(3,580	)
Additional paid-in capital		159,869			192,163			32,294			160,286			192,580			32,294
Accumulated deficit		(159,803	)		(178,348	)		(18,545	)		(167,443	)		(196,157	)		(28,714	)
Total stockholders' equity (deficit)		42			13,791			13,749			(7,165	)		(3,585	)		3,580
Total liabilities and stockholders' equity (deficit)		21,013			21,013			—			21,593			21,593			—

	*Three Months Ended*								*Three Months Ended*
	*September 30, 2025*								*September 30, 2024*
				*As Reported*			*Effect of*		*As Reported*			*As Adjusted*			*Effect of*
	*Under Old Policy*			*Under New Policy*			*Change*		*Under Old Policy*			*Under New Policy*			*Change*
Condensed Consolidated Statement of Operations
Gain (loss) from change in fair value of warrant liability	$	(2,157	)	$	1,591		$	3,748	$	(1,728	)	$	—		$	1,728
Transaction costs allocated to warrant liabilities		(530	)		(530	)		—		(993	)		—			993
Loss on issuance of warrant liabilities		(20,609	)		(20,609	)		—		(847	)		—			847
Net loss		(29,147	)		(25,399	)		3,748		(10,592	)		(7,024	)		3,568
Net loss per common share - basic and diluted		(0.78	)		(0.68	)		0.10		(2.85	)		(1.89	)		0.96
Other comprehensive income (loss)		(29,153	)		(25,405	)		3,748		(10,578	)		(7,010	)		3,568

	*Nine Months Ended*									*Nine Months Ended*
	*September 30, 2025*									*September 30, 2024*
				*As Reported*			*Effect of*			*As Reported*			*As Adjusted*			*Effect of*
	*Under Old Policy*			*Under New Policy*			*Change*			*Under Old Policy*			*Under New Policy*			*Change*
Condensed Consolidated Statement of Operations
Gain (loss) from change in fair value of warrant liability	$	16,506		$	1,031		$	(15,475	)	$	1,423		$	—		$	(1,423	)
Transaction costs allocated to warrant liabilities		(3,525	)		(1,737	)		1,788			(993	)		—			993
Loss on issuance of warrant liabilities		(38,760	)		(30,962	)		7,798			(847	)		—			847
Net loss		(43,223	)		(49,112	)		(5,889	)		(19,881	)		(19,464	)		417
Net loss per common share - basic and diluted		(2.08	)		(2.36	)		(0.28	)		(6.83	)		(6.69	)		0.14
Other comprehensive income (loss)		(43,226	)		(49,115	)		(5,889	)		(19,868	)		(19,451	)		417

	Three Months Ended									Three Months Ended
	June 30, 2025									June 30, 2024
	As Reported			As Adjusted			Effect of			As Reported			As Adjusted			Effect of
	Under Old Policy			Under New Policy			Change			Under Old Policy			Under New Policy			Change
Condensed Consolidated Statement of Operations
Gain (loss) from change in fair value of warrant liability	$	9,609		$	(560	)	$	(10,169	)	$	1,696		$	—		$	(1,696	)
Transaction costs allocated to warrant liabilities		(1,207	)		(1,207	)		—			—			—			—
Loss on issuance of warrant liabilities		(10,352	)		(10,352	)		—			—			—			—
Net loss		(7,640	)		(17,809	)		(10,169	)		(4,319	)		(6,015	)		(1,696	)
Net loss per common share - basic and diluted		(0.49	)		(1.15	)		(0.66	)		(1.70	)		(2.37	)		(0.67	)
Other comprehensive loss		(7,640	)		(17,809	)		(10,169	)		(4,311	)		(6,007	)		(1,696	)

	*Six Months Ended*									*Six Months Ended*
	*June 30, 2025*									*June 30, 2024*
	*As Reported*			*As Adjusted*			*Effect of*			*As Reported*			*As Adjusted*			*Effect of*
	*Under Old Policy*			*Under New Policy*			*Change*			*Under Old Policy*			*Under New Policy*			*Change*
Condensed Consolidated Statement of Operations
Gain (loss) from change in fair value of warrant liability	$	18,663		$	(560	)	$	(19,223	)	$	3,151		$	—		$	(3,151	)
Transaction costs allocated to warrant liabilities		(2,995	)		(1,207	)		1,788			—			—			—
Loss on issuance of warrant liabilities		(18,150	)		(10,352	)		7,798			—			—			—
Net loss		(14,076	)		(23,713	)		(9,637	)		(9,289	)		(12,440	)		(3,151	)
Net loss per common share - basic and diluted		(1.13	)		(1.90	)		(0.77	)		(3.71	)		(4.97	)		(1.26	)
Other comprehensive loss		(14,073	)		(23,710	)		(9,637	)		(9,290	)		(12,441	)		(3,151	)

	Three Months Ended									Three Months Ended
	March 31, 2025									March 31, 2024
	As Reported			As Adjusted			Effect of			As Reported			As Adjusted			Effect of
	Under Old Policy			Under New Policy			Change			Under Old Policy			Under New Policy			Change
Condensed Consolidated Statement of Operations
Gain from change in fair value of warrant liability	$	9,054		$	—		$	(9,054	)	$	1,455		$	—		$	(1,455	)
Transaction costs allocated to warrant liabilities		(1,788	)		—			1,788			—			—			—
Loss on issuance of warrant liabilities		(7,798	)		—			7,798			—			—			—
Net loss		(6,436	)		(5,904	)		532			(4,970	)		(6,425	)		(1,455	)
Net loss per common share - basic and diluted		(0.69	)		(0.63	)		0.06			(2.02	)		(2.61	)		(0.59	)
Other comprehensive loss		(6,433	)		(5,901	)		532			(4,979	)		(6,434	)		(1,455	)

The change in accounting policy did not have a material effect on the statement of cashflows for any current or prior period presented.