Clene (CLNN) 10-Q 8 May 24 2024 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 06, 2024
Document Information [Line Items]
Entity Central Index Key	0001822791
Entity Registrant Name	Clene Inc.
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2024
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	01-39834
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-2828339
Entity Address, Address Line One	6550 South Millrock Drive, Suite G50
Entity Address, City or Town	Salt Lake City
Entity Address, State or Province	UT
Entity Address, Postal Zip Code	84121
City Area Code	801
Local Phone Number	676-9695
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		128,433,721
Warrant [Member]
Document Information [Line Items]
Title of 12(b) Security	Warrants, to acquire one-half of one share of Common Stock for $11.50 per share
Trading Symbol	CLNNW
Security Exchange Name	NASDAQ
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	CLNN
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 21,732	$ 28,821
Marketable securities	6,178	6,179
Accounts receivable	64	143
Inventory	37	37
Prepaid expenses and other current assets	4,100	3,672
Total current assets	32,111	38,852
Restricted cash	58	58
Operating lease right-of-use assets	4,046	4,168
Property and equipment, net	8,854	9,263
TOTAL ASSETS	45,069	52,341
Current liabilities:
Accounts payable	1,645	1,504
Accrued liabilities	3,905	3,720
Operating lease obligations, current portion	599	576
Finance lease obligations, current portion	7	27
Notes payable, current portion	14,987	14,627
Convertible notes payable, current portion	5,042	4,876
Total current liabilities	26,185	25,330
Operating lease obligations, net of current portion	4,720	4,903
Notes payable, net of current portion	1,820	1,894
Convertible notes payable, net of current portion	5,265	5,258
Common stock warrant liabilities	2,790	1,481
Clene Nanomedicine contingent earn-out liability	22	75
Initial Stockholders contingent earn-out liability	3	10
TOTAL LIABILITIES	40,805	38,951
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.0001 par value: 300,000,000 and 300,000,000 shares authorized at March 31, 2024 and December 31, 2023, respectively; 128,433,721 and 128,422,851 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	13	13
Additional paid-in capital	257,914	255,901
Accumulated deficit	(253,803)	(242,723)
Accumulated other comprehensive income	140	199
TOTAL STOCKHOLDERS’ EQUITY	4,264	13,390
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 45,069	$ 52,341

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Dec. 30, 2020
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	128,433,721	128,422,851
Common stock, shares outstanding (in shares)	128,433,721	128,422,851

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue:
Total revenue	$ 73	$ 107
Operating expenses:
Cost of revenue	16	5
Research and development	5,869	7,395
General and administrative	3,420	3,439
Total operating expenses	9,305	10,839
Loss from operations	(9,232)	(10,732)
Other income (expense), net:
Interest income	359	172
Interest expense	(1,244)	(1,066)
Commitment share expense	0	(399)
Change in fair value of common stock warrant liabilities	(1,309)	0
Change in fair value of Clene Nanomedicine contingent earn-out liability	53	(55)
Change in fair value of Initial Stockholders contingent earn-out liability	7	(7)
Research and development tax credits and unrestricted grants	286	314
Other income, net	0	3
Total other income (expense), net	(1,848)	(1,038)
Net loss before income taxes	(11,080)	(11,770)
Income tax benefit	0	0
Net loss	(11,080)	(11,770)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	(4)	14
Foreign currency translation adjustments	(55)	4
Total other comprehensive income (loss)	(59)	18
Comprehensive loss	$ (11,139)	$ (11,752)
Net loss per share – basic and diluted (in dollars per share)	$ (0.09)	$ (0.15)
Weighted average common shares used to compute basic and diluted net loss per share (in shares)	128,427,231	76,049,665
Product [Member]
Revenue:
Total revenue	$ 44	$ 64
Royalty [Member]
Revenue:
Total revenue	$ 29	$ 43

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances (in shares) at Dec. 31, 2022	74,759,591
Balances at Dec. 31, 2022	$ 7	$ 196,246	$ (193,219)	$ 203	$ 3,237
Stock-based compensation expense	0	2,223	0	0	2,223
Unrealized loss on available-for-sale securities	0	0	0	14	14
Foreign currency translation adjustments	0	0	0	4	4
Net loss	$ 0	0	(11,770)	0	(11,770)
Issuance of common stock (in shares)	3,227,758
Issuance of common stock	$ 1	4,664	0	0	4,665
Balances (in shares) at Mar. 31, 2023	77,987,349
Balances at Mar. 31, 2023	$ 8	203,133	(204,989)	221	(1,627)
Balances (in shares) at Dec. 31, 2023	128,422,851
Balances at Dec. 31, 2023	$ 13	255,901	(242,723)	199	13,390
Stock-based compensation expense	$ 0	2,013	0	0	2,013
Issuance of common stock upon vesting of restricted stock awards (in shares)	10,870
Issuance of common stock upon vesting of restricted stock awards	$ 0	0	0	0	0
Unrealized loss on available-for-sale securities	0	0	0	(4)	(4)
Foreign currency translation adjustments	0	0	0	(55)	(55)
Net loss	$ 0	0	(11,080)	0	(11,080)
Balances (in shares) at Mar. 31, 2024	128,433,721
Balances at Mar. 31, 2024	$ 13	$ 257,914	$ (253,803)	$ 140	$ 4,264

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (11,080)	$ (11,770)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	420	402
Non-cash lease expense	122	108
Commitment share expense	0	399
Change in fair value of common stock warrant liabilities	1,309	0
Change in fair value of Clene Nanomedicine contingent earn-out liability	(53)	55
Change in fair value of Initial Stockholders contingent earn-out liability	(7)	7
Stock-based compensation expense	2,013	2,223
Accretion of debt discount	367	250
Non-cash interest income on marketable securities	(81)	0
Non-cash interest expense on notes payable	91	82
Changes in operating assets and liabilities:
Accounts receivable	79	126
Inventory	0	(45)
Prepaid expenses and other current assets	(428)	(581)
Accounts payable	141	(2,406)
Accrued liabilities	185	2,070
Operating lease obligations	(160)	(138)
Net cash used in operating activities	(7,082)	(9,218)
Cash flows from investing activities:
Purchases of marketable securities	(6,168)	0
Proceeds from maturities of marketable securities	6,250	5,000
Purchases of property and equipment	(11)	(278)
Net cash provided by investing activities	71	4,722
Cash flows from financing activities:
Proceeds from issuance of common stock and warrants, net of offering costs	0	4,266
Payments of finance lease obligations	(19)	(28)
Proceeds from the issuance of notes payable	0	350
Net cash provided by (used in) financing activities	(19)	4,588
Effect of foreign exchange rate changes on cash and restricted cash	(59)	18
Net increase (decrease) in cash, cash equivalents and restricted cash	(7,089)	110
Cash, cash equivalents and restricted cash – beginning of period	28,879	18,390
Cash, cash equivalents and restricted cash – end of period	21,790	18,500
Reconciliation of cash, cash equivalents and restricted cash to the consolidated balance sheets
Cash and cash equivalents	21,732	18,442
Restricted cash	58	58
Cash, cash equivalents and restricted cash	21,790	18,500
Supplemental cash flow information:
Cash paid for interest expense	$ 784	$ 982

Note 1 - Nature of the Business

Note 1 - Nature of the Business	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Business Description and Basis of Presentation [Text Block]	Note 1. Clene Inc. (the “Company,” “we,” “us,” or similar such references) is a clinical-stage pharmaceutical company pioneering the discovery, development, and commercialization of novel clean-surfaced nanotechnology therapeutics. We have developed an electro-crystal-chemistry drug development platform which enables production of concentrated, stable, highly active, clean-surfaced nanocrystal suspensions. We have multiple drug assets currently in development for applications primarily in neurology. Our efforts are currently focused on addressing the high unmet medical needs in central nervous system disorders including amyotrophic lateral sclerosis (“ALS”), multiple sclerosis (“MS”), and Parkinson’s disease (“PD”). Our patented electro-crystal-chemistry manufacturing platform further enables us to develop very low concentration dietary supplements to advance the health and well-being of broad populations. These dietary supplements can vary greatly and include nanocrystals of varying composition, shapes and sizes as well as ionic solutions with diverse metallic constituents. Dietary supplements are marketed and distributed through our wholly owned subsidiary, dOrbital, Inc., or through an exclusive license with 4Life “4Life” 15 Clene Nanomedicine, Inc. (“Clene Nanomedicine”) became a public company on December 30, 2020 ( Going Concern We incurred a loss from operations of $9.2 million and $10.7 million for the three March 31, 2024 2023 March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 three March 31, 2024 2023 We have incurred significant losses and negative cash flows from operations since our inception. We have not not twelve not 8 To mitigate our funding needs, we plan to raise additional funding, including exploring equity financing and offerings, debt financing, licensing or collaboration arrangements with third third no not one The accompanying condensed consolidated financial statements have been prepared assuming we will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. As a result, the accompanying condensed consolidated financial statements do not may

Note 2 - Summary of Significant

Note 2 - Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Significant Accounting Policies [Text Block]	Note 2. Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of Clene Inc. and our wholly-owned subsidiaries, Clene Nanomedicine, Inc., a subsidiary incorporated in Delaware, Clene Australia Pty Ltd (“Clene Australia”), a subsidiary incorporated in Australia, Clene Netherlands B.V. (“Clene Netherlands”), a subsidiary incorporated in the Netherlands, and dOrbital, Inc., a subsidiary incorporated in Delaware, after elimination of all intercompany accounts and transactions. We have prepared the accompanying condensed consolidated financial statements in accordance with United States (“U.S.”) Generally Accepted Accounting Principles (“GAAP”) for interim financial reporting and as required by Regulation S- X, 10 01. three March 31, 2024 2023 Results of operations for the three March 31, 2024 2023 not three March 31, 2024 2023 10 Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and disclosure of contingent assets and liabilities, and the reported amounts of expenses. We base our estimates on historical experience and various other assumptions that we believe to be reasonable. Actual results may Risks and Uncertainties We are subject to certain risks and uncertainties and believe that changes in any of the following areas could have a material adverse effect on future financial condition, results of operations, or cash flows: ability to obtain additional financing; regulatory approval and market acceptance of, and reimbursement for, product candidates; performance of third no Concentrations of Credit Risk Financial instruments which potentially subject us to significant concentrations of credit risk consist primarily of cash. Our cash is held in financial institutions and amounts on deposit may not not Cash and Cash Equivalents We consider all short-term investments with original maturities of 90 Restricted Cash We classify cash as restricted when it is unavailable for withdrawal or use in our general operating activities. Restricted cash is classified as current and noncurrent on the condensed consolidated balance sheets based on the nature of the restriction. Our restricted cash balance includes contractually restricted deposits related to our corporate credit card. Marketable Securities Marketable securities are investments with original maturities of more than 90 not one Inventory Inventory is stated at historic cost on a first first March 31, 2024 December 31, 2023 Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Property and equipment consist of laboratory and office equipment, computer software, and leasehold improvements. Depreciation is calculated using the straight-line method over the estimated economic useful lives of the assets, which are 3 to 5 years for laboratory equipment, 3 to 7 years for furniture and fixtures, and 2 to 5 years for computer software. Leasehold improvements are amortized over the lesser of the estimated lease term or the estimated useful life of the assets. Costs for capital assets not not We capitalize costs to obtain or develop computer software for internal use, including development costs incurred during the software development stage and costs to obtain software for access and conversion of historical data. We also capitalize costs to modify, upgrade, or enhance existing internal-use software that result in additional functionality. We expense costs incurred during the preliminary project stage, training costs, data conversion costs, and maintenance costs. Debt When debt is issued and a derivative is required to be separated (e.g., bifurcated conversion option) or another separate freestanding financial instrument (e.g., warrant) is issued, costs and fees incurred are allocated to the instruments issued (or bifurcated) in proportion to the allocation of proceeds. When some portions of the costs and fees relate to a bifurcated derivative or freestanding financial instrument that is being subsequently measured at fair value, those allocated costs are expensed immediately. Debt discounts, debt premiums, and debt issuance costs related to debt are recorded as deductions that net against the principal value of the debt and are amortized to interest expense over the contractual term of the debt using the effective interest method. In accordance with ASC 470 20, Debt with Conversion and Other Options not 480, Distinguishing Liabilities from Equity 480” Convertible Debt In accordance with ASU 2020 06, Debt—Debt with Conversion and Other Options (Subtopic 470 20 815 40 not not not no 815, Derivatives and Hedging 815” Leases At inception of a contract, we determine if a contract meets the definition of a lease. We determine if the contract conveys the right to control the use of an identified asset for a period of time. We assess throughout the period of use whether we have both of the following: (i) the right to obtain substantially all the economic benefits from use of the identified asset, and (ii) the right to direct the use of the identified asset. This determination is reassessed if the terms of the contract are changed. Leases are classified as operating or finance leases based on the terms of the lease agreement and certain characteristics of the identified asset. Right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of the future lease payments less any lease incentives received. At the lease commencement date, the discount rate implicit in the lease is used to discount the lease liability if readily determinable. If not not not twelve Certain lease agreements may not Leases may not Contingent Earn-Out Liabilities In connection with the Reverse Recapitalization, certain Clene Nanomedicine stockholders are entitled to receive additional shares of Common Stock (the “Clene Nanomedicine Contingent Earn-out”) as follows: (i) 3,338,483 shares if (a) the volume-weighted average price (“VWAP”) of our Common Stock equals or exceeds $15.00 (the “Milestone 1 twenty thirty three 1 three 1” 2 twenty thirty five 2 five 2” 1 not 2 1. 1; 2. 1 not 2 1. In accordance with ASC 815, not Common Stock Warrants We account for common stock warrants as either equity- or liability-classified instruments based on an assessment of the warrant terms. The assessment considers whether the warrants are freestanding financial instruments pursuant to ASC 480, 480, 815, Grant Funding We may 20, Accounting for Government Grants and Disclosure of Government Assistance 20” 4 We recognize grant funding with conditions or continuing performance obligations as a reduction in research and development expenses in the period during which the related qualifying expenses are incurred and as the conditions or performance obligations are fulfilled. Any amount received in advance of fulfilling such conditions or performance obligations is recorded in accrued liabilities (see Note 6 twelve three March 31, 2024 2023 Foreign Currency Translation and Transactions Our functional and reporting currency is the U.S. dollar (“USD”). Clene Australia and Clene Netherlands determined their functional currencies to be the Australian dollar and Euro, respectively. The results of our foreign currency operations are translated into USD at the average exchange rates during the period, assets and liabilities are translated using the exchange rate as of the balance sheet date, and stockholders’ equity is translated using historical rates. Adjustments from the translation of the results of our foreign currency operations are excluded from net loss and are accumulated in a separate component of stockholders’ equity. We also incur foreign exchange transaction gains and losses for purchases denominated in foreign currencies. Foreign exchange transaction gains and losses are included in other income (expense), net, as incurred. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The only elements of other comprehensive loss in any periods presented were the translation of foreign currency denominated balances of Clene Australia and Clene Netherlands to USD for consolidation and our unrealized gain (loss) on available-for-sale securities. Segment Information We report segment information based on ASC 280 Segment Reporting 280” may fourth 2023, 280, fourth 2023, two not Income Taxes We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the condensed consolidated financial statements or in our tax returns. Deferred tax assets and liabilities are determined based on the differences between the financial statement basis and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. We assess the likelihood that our deferred tax assets will be recovered from future taxable income and, to the extent we believe, based upon the weight of available evidence, that it is more likely than not not We account for uncertainty in income taxes recognized in the condensed consolidated financial statements by applying a two not may 50% Stock-Based Compensation We account for stock-based compensation arrangements using a fair value-based method for costs related to all share-based payments including stock options and stock awards. Stock-based compensation expense is recorded in research and development and general and administrative expenses based on the classification of the work performed by the grantees. The fair value is recognized over the period during which a grantee is required to provide services in exchange for the option award and service-based stock awards, known as the requisite service period (usually the vesting period), on a straight-line basis. For stock awards with market conditions, the fair value is recognized over the period based on the expected milestone achievement dates as the derived service period (usually the vesting period), on a straight-line basis. For stock awards with performance conditions, the grant-date fair value of these awards is the market price on the applicable grant date, and compensation expense will be recognized when the conditions become probable of being satisfied. We recognize a cumulative true-up adjustment once the conditions become probable of being satisfied as the related service period had been completed in a prior period. We elect to account for forfeitures as they occur, rather than estimating expected forfeitures. We determine the fair value of each share of Common Stock underlying stock-based awards using a Black-Scholes option pricing model based on the closing price of our Common Stock as reported by Nasdaq on the date of grant. The fair value of stock awards with market conditions are determined using a Monte Carlo valuation model. Recent Accounting Pronouncements Not In November 2023, 2023 07, Segment Reporting (Topic 280 2023 07” 2023 07 280 2023 07, December 15, 2023, December 15, 2024. 2023 07. In December 2023, 2023 09, Income Taxes (Topic 740 2023 09” 2023 09 December 15, 2024. 2023 09.

Note 3 - Cash, Cash Equivalents

Note 3 - Cash, Cash Equivalents, and Marketable Securities	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Cash, Cash Equivalents, and Marketable Securities [Text Block]	Note 3. Available-for-Sale Securities Available-for-sale securities as of March 31, 2024 March 31, 2024 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash equivalents (contractual maturity within 90 days): U.S. Treasury securities $ 12,192 $ — $ (1 ) $ 12,191 Money market funds 5,660 — — 5,660 Total cash equivalents 17,852 — (1 ) 17,851 Cash 3,881 — — 3,881 Total cash and cash equivalents $ 21,733 $ — $ (1 ) $ 21,732 Marketable securities (contractual maturity greater than 90 days but less than 1 year): U.S. Treasury securities $ 6,179 $ — $ (1 ) $ 6,178 Total marketable securities $ 6,179 $ — $ (1 ) $ 6,178 Available-for-sale securities as of December 31, 2023 December 31, 2023 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash equivalents (contractual maturity within 90 days): U.S. Treasury securities $ 19,883 $ 1 $ — $ 19,884 Money market funds 5,113 — — 5,113 Total cash equivalents 24,996 1 — 24,997 Cash 3,824 — — 3,824 Total cash and cash equivalents $ 28,820 $ 1 $ — $ 28,821 Marketable securities (contractual maturity greater than 90 days but less than 1 year): U.S. Treasury securities $ 6,179 $ — $ — $ 6,179 Total marketable securities $ 6,179 $ — $ — $ 6,179 We received proceeds of $6.3 million and $5.0 million from the maturity of marketable securities during the three March 31, 2024 2023 no three March 31, 2024 2023 March 31, 2024 December 31, 2023 not

Note 4 - Prepaid Expenses and O

Note 4 - Prepaid Expenses and Other Current Assets	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Prepaid Expenses and Other Current Assets [Text Block]	Note 4. Prepaid expenses and other current assets as of March 31, 2024 December 31, 2023 March 31, December 31, (in thousands) 2024 2023 Metals to be used in research and development $ 1,826 $ 1,909 Research and development tax credits receivable 1,442 1,195 Other 832 568 Total prepaid expenses and other current assets $ 4,100 $ 3,672

Note 5 - Property and Equipment

Note 5 - Property and Equipment, Net	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Property, Plant and Equipment Disclosure [Text Block]	Note 5. Property and equipment, net, as of March 31, 2024 December 31, 2023 March 31, December 31, (in thousands) 2024 2023 Lab equipment $ 4,065 $ 4,092 Office equipment 177 178 Computer software 459 459 Leasehold improvements 9,983 9,983 Construction in progress 1,449 1,438 16,133 16,150 Less accumulated depreciation (7,279 ) (6,887 ) Total property and equipment, net $ 8,854 $ 9,263 Depreciation expense recorded in research and development expense and general and administrative expense for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 General and administrative $ 66 $ 67 Research and development 354 335 Total depreciation expense $ 420 $ 402

Note 6 - Accrued Liabilities

Note 6 - Accrued Liabilities	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	Note 6. Accrued liabilities as of March 31, 2024 December 31, 2023 March 31, December 31, (in thousands) 2024 2023 Accrued compensation and benefits $ 2,628 $ 2,120 Accrued CRO and clinical fees 746 481 Other 531 1,119 Total accrued liabilities $ 3,905 $ 3,720

Note 7 - Leases

Note 7 - Leases	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Lessee, Operating and Finance Leases [Text Block]	Note 7. We lease laboratory and office space and certain laboratory equipment under non-cancellable operating and finance leases. The carrying value of our right-of-use lease assets is substantially concentrated in our real estate leases, while the volume of lease agreements is primarily concentrated in equipment leases. We expect that, in the normal course of business, the existing leases will be renewed or replaced by similar leases. Operating Leases Operating leases primarily consist of real estate leases for office and laboratory space. We have three real estate leases: (i) a laboratory and manufacturing facility which commenced in September 2021 ten two five February 2022 seven two five September 2022 seven five not not As of March 31, 2024 December 31, 2023 Finance Leases Assets recorded under finance lease obligations and included within property and equipment as of March 31, 2024 December 31, 2023 March 31, December 31, (in thousands) 2024 2023 Lab equipment $ 636 $ 636 Less accumulated depreciation (469 ) (449 ) Net $ 167 $ 187 As of March 31, 2024 December 31, 2023 Maturity Analysis of Lease Obligations The maturity analysis of our finance and operating lease obligations as of March 31, 2024 (in thousands) Finance Leases Operating Leases 2024 (remainder) $ 7 $ 789 2025 — 1,208 2026 — 1,236 2027 — 1,132 2028 — 1,093 2029 — 649 Thereafter — 1,045 Total minimum lease payments 7 7,152 Less amount representing interest/discounting — (1,833 ) Present value of minimum lease payments 7 5,319 Less lease obligations, current portion (7 ) (599 ) Lease obligations, net of current portion $ — $ 4,720 Components of Lease Cost The components of finance and operating lease costs for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 Finance lease costs: Amortization $ 27 $ 20 Interest on lease liabilities — 6 Operating lease costs 254 253 Variable lease costs 53 50 Total lease costs $ 334 $ 329 Supplemental Cash Flow Information Three Months Ended March 31, (in thousands) 2024 2023 Operating cash flows from operating leases $ (307 ) $ (303 ) Operating cash flows from finance leases $ — $ (6 ) Financing cash flows from finance leases $ (19 ) $ (28 )

Note 8 - Notes Payable and Conv

Note 8 - Notes Payable and Convertible Notes Payable	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Debt Disclosure [Text Block]	Note 8. Our notes payable and convertible notes payable as of March 31, 2024 December 31, 2023 Stated March 31, December 31, (in thousands, except interest rates) Interest Rate 2024 2023 Notes payable Advance Cecil, Inc. (commenced April 2019) 8.00 % $ 140 $ 138 Maryland DHCD (commenced February 2019) 8.00 % 704 694 Maryland DHCD (commenced May 2022) 6.00 % 1,083 1,083 Avenue Venture Opportunities Fund, L.P. (commenced May 2021) 15.10 % 15,000 15,000 16,927 16,915 Less unamortized discount and debt issuance costs (120 ) (394 ) Less notes payable, current portion, net of unamortized discount and debt issuance costs (14,987 ) (14,627 ) Total notes payable, net of current portion $ 1,820 $ 1,894 Convertible notes payable Avenue Venture Opportunities Fund, L.P. (commenced May 2021) 15.10 % $ 5,000 $ 5,000 Maryland DHCD (commenced December 2022) 6.00 % 5,388 5,308 10,388 10,308 Less unamortized discount and debt issuance costs (81 ) (174 ) Less convertible notes payable, current portion, net of unamortized discount and debt issuance costs (5,042 ) (4,876 ) Total convertible notes payable, net of current portion $ 5,265 $ 5,258 Maryland Loans In February 2019, “2019 not 2019 2019 February 22, 2034, March 31, 2024 December 31, 2023 2019 three March 31, 2024 2023 In April 2019, “2019 2019 2019 April 30, 2034, March 31, 2024 December 31, 2023 2019 three March 31, 2024 2023 In May 2022, “2022 March 31, 2024 May 17, 2024. first 12 July 1, 2022, 18 $15,000 30 July 1, 2027. March 31, 2024 December 31, 2023 first three March 31, 2024 2023 In December 2022, “2022 first 12 January 1, 2023, 48 January 1, 2028. March 31, 2024 December 31, 2023 December 8, 2023, may, 30 not three March 31, 2024 2023 Avenue Loan In May 2021, “2021 March 31, 2024 December 31, 2023 May 2021 September 2021 ( 1” 2” not first 12 12 12 June 30, 2024), June 2023 ( June 2023 ( 1” may December 31, 2024, 1, June 30, 2024 ( 2” December 1, 2024, may December 1, 2025, no 2 At any time between May 21, 2022 May 21, 2024, may, not March 31, 2024 December 31, 2023 three March 31, 2024 2023 We are subject to covenants until maturity, including limitations on our ability to retire, repurchase, or redeem our stock, options, and warrants other than per the terms of the securities; limitations on our ability to pay dividends; and we are required to maintain unrestricted cash and cash equivalents of at least $5.0 million. We are not 2021 2021 three March 31, 2024 2023 At the inception of the 2021 2021 may no Debt Maturities Future debt payments, net of unamortized discounts and debt issuance costs, and without giving effect to any potential future exercise of conversion features, are as follows: (in thousands) 2019 MD Loan 2019 Cecil Loan 2021 Avenue Loan 2022 MD Loan 2022 DHCD Loan 2024 (remainder) $ — $ — $ 20,000 $ — $ — 2025 — — — 347 — 2026 — — — 369 — 2027 — — — 317 — 2028 — — — — 5,000 2029 — — — — — Thereafter 500 100 — — — Total debt principal payments 500 100 20,000 1,033 5,000 Accrued and unpaid interest 204 40 — 50 388 Less unamortized discount and debt issuance costs — — (134 ) (20 ) (47 ) Future debt payments, net $ 704 $ 140 $ 19,866 $ 1,063 $ 5,341

Note 9 - Commitments and Contin

Note 9 - Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	Note 9. Commitments We enter into agreements in the normal course of business with CROs for clinical trials and with vendors for preclinical studies and other services and products for operating purposes, which are cancelable at any time by us, subject to payment of our remaining obligations under binding purchase orders and, in certain cases, nominal early termination fees. These commitments are not As of March 31, 2024 December 31, 2023 Contingencies From time to time, we may not We received the following grants from the National Multiple Sclerosis Society (“NMSS”): (i) $0.3 million in September 2019 ( “2019 2 May 2023 ( “2023 2 Au8 first not 2019 2023 2019 2023 twelve Au8 Au8 third Au8 2019 Au8 2023 March 31, 2024 not not 450, Contingencies no 2019 2023

Note 10 - Income Taxes

Note 10 - Income Taxes	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Income Tax Disclosure [Text Block]	Note 10. The components of loss before income taxes for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 United States $ (11,039 ) $ (11,546 ) Foreign (41 ) (224 ) Net loss before income taxes $ (11,080 ) $ (11,770 ) We are subject to taxation in the U.S., Australia, Netherlands, and various state jurisdictions. Our tax returns from 2017 no

Note 11 - Benefit Plans

Note 11 - Benefit Plans	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Share-Based Payment Arrangement [Text Block]	Note 11. 401 Our 401 401 401 three March 31, 2024 2023 Stock Compensation Plans The Clene Nanomedicine, Inc. 2014 “2014 July 2014. no may 2014 March 31, 2024 2014 The Clene Inc. 2020 “2020 December 2020 May 2023 March 31, 2024 2020 Stock-Based Compensation Expense Stock-based compensation expense recorded in research and development expense and general and administrative expense for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 General and administrative $ 1,136 $ 1,250 Research and development 877 973 Total stock-based compensation expense $ 2,013 $ 2,223 Stock-based compensation expense by award type for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 Stock options $ 2,002 $ 2,222 Stock awards 11 1 Total stock-based compensation expense $ 2,013 $ 2,223 Stock Options Outstanding stock options and related activity for the three March 31, 2024 (in thousands, except share, per share, and term data) Number of Options Weighted Average Exercise Price Per Share Weighted Average Remaining Term (Years) Intrinsic Value Outstanding – December 31, 2023 21,846,388 $ 2.26 7.28 $ 302 Granted 280,070 0.44 9.95 — Forfeited (141,124 ) 5.33 — — Outstanding – March 31, 2024 21,985,334 $ 2.22 7.07 $ 568 Vested and exercisable – March 31, 2024 12,511,524 $ 2.55 5.79 $ 567 Vested, exercisable or expected to vest – March 31, 2024 21,985,334 $ 2.22 7.07 $ 568 As of March 31, 2024 December 31, 2023 The weighted-average grant-date fair value of stock options granted during the three March 31, 2024 2023 three March 31, 2024 2023 Three Months Ended March 31, 2024 2023 Expected stock price volatility 99.99 % 96.22% –103.24 % Risk-free interest rate 4.04 % 3.38% –3.98 % Expected dividend yield 0.00 % 0.00 % Expected term of options (in years) 5.00 5.00 –6.08 Stock Awards Stock awards include rights to restricted stock awards with market-based vesting conditions and restricted stock units with service-based vesting conditions. Outstanding stock awards and related activity for the three March 31, 2024 Number of Stock Awards Weighted Average Grant Date Fair Value Unvested balance – December 31, 2023 778,815 $ 9.72 Converted to shares of Common Stock upon vesting (10,870 ) 1.15 Unvested balance – March 31, 2024 767,945 $ 9.84 As of March 31, 2024 no December 31, 2023

Note 12 - Fair Value

Note 12 - Fair Value	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Fair Value Disclosures [Text Block]	Note 12. Cash, cash equivalents, and marketable securities are carried at fair value. Financial instruments, including accounts receivable, accounts payable, and accrued expenses are carried at cost, which approximates fair value given their short-term nature. Our remaining fair value measures are discussed below. Financial Instruments with Fair Value Measurements on a Recurring Basis The fair value hierarchy for financial instruments measured at fair value on a recurring basis as of March 31, 2024 March 31, 2024 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: U.S. Treasury securities $ — $ 12,191 $ — $ 12,191 Money market funds 5,660 — — 5,660 Marketable securities: U.S. Treasury securities — 6,178 — 6,178 Common stock warrant liabilities — — 2,790 2,790 Clene Nanomedicine contingent earn-out liability — — 22 22 Initial Stockholders contingent earn-out liability — — 3 3 The fair value hierarchy for financial instruments measured at fair value on a recurring basis as of December 31, 2023 December 31, 2023 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: U.S. Treasury securities $ — $ 19,884 $ — $ 19,884 Money market funds 5,113 — — 5,113 Marketable securities: U.S. Treasury securities — 6,179 — 6,179 Common stock warrant liabilities — — 1,481 1,481 Clene Nanomedicine contingent earn-out liability — — 75 75 Initial Stockholders contingent earn-out liability — — 10 10 There were no 1, 2, 3 Changes in the fair value of our Level 3 three March 31, 2024 (in thousands) Common Stock Warrant Liabilities Clene Nanomedicine Contingent Earn-out Initial Stockholders Contingent Earn-out Balance – December 31, 2023 $ 1,481 $ 75 $ 10 Change in fair value 1,309 (53 ) (7 ) Balance – March 31, 2024 $ 2,790 $ 22 $ 3 Changes in the fair value of our Level 3 three March 31, 2023 (in thousands) Clene Nanomedicine Contingent Earn-out Initial Stockholders Contingent Earn-out Balance – December 31, 2022 $ 2,264 $ 291 Change in fair value 55 7 Balance – March 31, 2023 $ 2,319 $ 298 Valuation of Notes Payable and Convertible Notes Payable The 2019 2019 8 2021 2022 2022 3 Valuation of the Common Stock Warrant Liabilities The New Avenue Warrant is classified as a liability and carried at fair value. We estimate the fair value using a Black-Scholes option-pricing model with probability weights for the occurrence of the following events: (i) settlement of the instrument upon a change of control transaction, (ii) dissolution of the Company, or (iii) another outcome outside of (i)-(ii). These estimates require significant judgment. The carrying amount may may March 31, December 31, 2024 2023 Expected stock price volatility 105.00% – 120.00 % 105.00% – 110.00 % Risk-free interest rate 4.28% 5.38 % 3.88% 5.03 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 0.50 – 4.25 0.75 – 4.50 Probability of change of control 20.00 % 25.00 % Probability of dissolution 50.00 % 50.00 % Probability of other outcome 30.00 % 25.00 % The Tranche A Warrants are classified as a liability and carried at fair value (the Tranche B Warrants qualified for equity classification at issuance). We estimate the fair value using a Black-Scholes option-pricing model with probability weights for the occurrence of the following events: (i) FDA acceptance of an NDA for CNM- Au8, may may March 31, December 31, 2024 2023 Expected stock price volatility 100.00% 105.00 % 100.00% 110.00 % Risk-free interest rate 4.55% 5.15 % 4.13% 4.74 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 0.83 2.21 1.08 2.46 Probability of NDA acceptance 20.00 % 20.00 % Probability of fundamental transaction 20.00 % 25.00 % Probability of dissolution 50.00 % 50.00 % Probability of other outcome 10.00 % 5.00 % Valuation of the Contingent Earn-Out Liabilities The Contingent Earn-outs are carried at fair value, determined using a Monte Carlo valuation model in order to simulate the future path of our stock price over the earn-out periods. The carrying amount of the liabilities may may March 31, December 31, 2024 2023 Expected stock price volatility 97.50 % 115.00 % Risk-free interest rate 4.70 % 4.20 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 1.75 2.00

Note 13 - Capital Stock

Note 13 - Capital Stock	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Equity [Text Block]	Note 13. As of March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 no Our common stockholders are entitled to one No not Common Stock Warrants As of March 31, 2024 December 31, 2023 Number of Shares Issuable March 31, December 31, Date Exercisable Exercise Price Expiration Classification 2024 2023 December 2020 $ 11.50 December 2025 (1) Equity 2,407,500 2,407,500 December 2020 $ 11.50 December 2025 (2) Equity 24,583 24,583 June 2023 $ 0.80 June 2028 (3) Liability 3,000,000 3,000,000 June 2023 $ 1.10 June 2026 (4) Liability 50,000,000 50,000,000 June 2023 $ 1.50 June 2030 (5) Equity 50,000,000 50,000,000 Total 105,432,083 105,432,083 ( 1 Represents 2,407,500 shares of Common Stock underlying warrants to purchase one 1/2 one may March 31, 2024 December 31, 2023 no ( 2 Represents 24,583 shares of Common Stock underlying warrants to purchase one 1/2 one July 2021. March 31, 2024 December 31, 2023 no ( 3 Represents 3,000,000 shares of Common Stock underlying the New Avenue Warrant, issued pursuant to the Second Amendment (see Note 8 March 31, 2024 December 31, 2023 not ( 4 Represents 50,000,000 shares of Common Stock underlying the Tranche A Warrants to purchase one June 2023 March 31, 2024 December 31, 2023 no ( 5 Represents 50,000,000 shares of Common Stock underlying the Tranche B Warrants to purchase one June 2023 March 31, 2024 December 31, 2023 no Public Offerings In June 2023, may sixty 60 Au8 June 16, 2026. sixty 60 Au8 June 16, 2030. 3 333 264299 April 26, 2022, 462 333 272692 June 16, 2023, 815, December 31, 2023. Common Stock Sales Agreement In April 2022, December 2022 ( may 3 333 264299 April 26, 2022. May 8, 2024 Pursuant to the ATM Agreement, Canaccord is not not three March 31, 2024 three March 31, 2023 Common Stock Purchase Agreement On March 3, 2023, March 7, 2023. 3 333 264299 April 26, 2022. June 16, 2023, not Pursuant to the Purchase Agreement, we may may not not not may may On the date of the Purchase Agreement, we issued 332,668 shares of Common Stock (the “Initial Commitment Shares”) to Lincoln Park as an initial fee for its commitment under the Purchase Agreement. We recorded the fair value of the Initial Commitment Shares on the date of issuance in other income (expense), net. We may may first may, not 61st may one We evaluated the Purchase Agreement under ASC 815 40 Derivatives and Hedging—Contracts on an Entity's Own Equity not no March 31, 2024 December 31, 2023 not three March 31, 2024 2023

Note 14 - Net Loss Per Share

Note 14 - Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Earnings Per Share [Text Block]	Note 14. The computation of basic and diluted net loss per share attributable to common stockholders for the three March 31, 2024 2023 Three Months Ended March 31, (in thousands, except share and per share data) 2024 2023 Numerator: Net loss attributable to common stockholders $ (11,080 ) $ (11,770 ) Denominator: Weighted average common shares outstanding 128,427,231 76,049,665 Net loss per share attributable to common stockholders – basic and diluted $ (0.09 ) $ (0.15 ) The following shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the three March 31, 2024 2023 not Three Months Ended March 31, 2024 2023 Convertible notes payable (see Note 8) 1,732,703 1,732,703 Common stock warrants (see Note 13) 105,432,083 4,477,045 Options to purchase common stock (see Note 11) 21,985,334 16,205,404 Unvested restricted stock awards (see Note 11) 767,945 812,170 Contingent earn-out shares (see Note 2) 6,592,334 6,592,334 Total 136,510,399 29,819,656

Note 15 - Related Party Transac

Note 15 - Related Party Transactions	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Related Party Transactions Disclosure [Text Block]	Note 15. License and Supply Agreements In August 2018, 4Life’s March 31, 2024, April 25, 2024, 4Life 4Life ● Supply Agreement 4Life, 4Life 2024 2033 2033, 4Life. may 4Life’s 4Life two 4Life License Agreement ● License Agreement 4Life 4Life 4Life 4Life may 4Life January 1, 2027, third December 31, 2033, 4Life five We currently provide an aqueous zinc-silver ion dietary (mineral) supplement to 4Life, 4Life 4Life three March 31, 2024 2023 Three Months Ended March 31, (in thousands) 2024 2023 Product revenue from related parties $ 43 $ 63 Royalty revenue from related parties 29 43 Total revenue from related parties $ 72 $ 106

Note 16 - Subsequent Events

Note 16 - Subsequent Events	3 Months Ended
	Mar. 31, 2024
Notes to Financial Statements
Subsequent Events [Text Block]	Note 16. Other than as described above under Note 13 15 April 9, 2024, first October 2023 four Au8 may may August 31, 2027. may September 25, 2023 August 31, 2024. September 25, 2023

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Insider Trading Arr Line Items
Material Terms of Trading Arrangement [Text Block]	5. During the three March 31, 2024 none 10b5 1 10b5 1 408
Rule 10b5-1 Arrangement Terminated [Flag]	false
Rule 10b5-1 Arrangement Adopted [Flag]	false
Non-Rule 10b5-1 Arrangement Terminated [Flag]	false
Non-Rule 10b5-1 Arrangement Adopted [Flag]	false

Significant Accounting Policies

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of Clene Inc. and our wholly-owned subsidiaries, Clene Nanomedicine, Inc., a subsidiary incorporated in Delaware, Clene Australia Pty Ltd (“Clene Australia”), a subsidiary incorporated in Australia, Clene Netherlands B.V. (“Clene Netherlands”), a subsidiary incorporated in the Netherlands, and dOrbital, Inc., a subsidiary incorporated in Delaware, after elimination of all intercompany accounts and transactions. We have prepared the accompanying condensed consolidated financial statements in accordance with United States (“U.S.”) Generally Accepted Accounting Principles (“GAAP”) for interim financial reporting and as required by Regulation S- X, 10 01. three March 31, 2024 2023 Results of operations for the three March 31, 2024 2023 not three March 31, 2024 2023 10
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and disclosure of contingent assets and liabilities, and the reported amounts of expenses. We base our estimates on historical experience and various other assumptions that we believe to be reasonable. Actual results may
Risk and Uncertainties [Policy Text Block]	Risks and Uncertainties We are subject to certain risks and uncertainties and believe that changes in any of the following areas could have a material adverse effect on future financial condition, results of operations, or cash flows: ability to obtain additional financing; regulatory approval and market acceptance of, and reimbursement for, product candidates; performance of third no
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Concentrations of Credit Risk Financial instruments which potentially subject us to significant concentrations of credit risk consist primarily of cash. Our cash is held in financial institutions and amounts on deposit may not not
Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents We consider all short-term investments with original maturities of 90
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash We classify cash as restricted when it is unavailable for withdrawal or use in our general operating activities. Restricted cash is classified as current and noncurrent on the condensed consolidated balance sheets based on the nature of the restriction. Our restricted cash balance includes contractually restricted deposits related to our corporate credit card.
Marketable Securities, Policy [Policy Text Block]	Marketable Securities Marketable securities are investments with original maturities of more than 90 not one
Inventory, Policy [Policy Text Block]	Inventory Inventory is stated at historic cost on a first first March 31, 2024 December 31, 2023
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Property and equipment consist of laboratory and office equipment, computer software, and leasehold improvements. Depreciation is calculated using the straight-line method over the estimated economic useful lives of the assets, which are 3 to 5 years for laboratory equipment, 3 to 7 years for furniture and fixtures, and 2 to 5 years for computer software. Leasehold improvements are amortized over the lesser of the estimated lease term or the estimated useful life of the assets. Costs for capital assets not not We capitalize costs to obtain or develop computer software for internal use, including development costs incurred during the software development stage and costs to obtain software for access and conversion of historical data. We also capitalize costs to modify, upgrade, or enhance existing internal-use software that result in additional functionality. We expense costs incurred during the preliminary project stage, training costs, data conversion costs, and maintenance costs.
Debt, Policy [Policy Text Block]	Debt When debt is issued and a derivative is required to be separated (e.g., bifurcated conversion option) or another separate freestanding financial instrument (e.g., warrant) is issued, costs and fees incurred are allocated to the instruments issued (or bifurcated) in proportion to the allocation of proceeds. When some portions of the costs and fees relate to a bifurcated derivative or freestanding financial instrument that is being subsequently measured at fair value, those allocated costs are expensed immediately. Debt discounts, debt premiums, and debt issuance costs related to debt are recorded as deductions that net against the principal value of the debt and are amortized to interest expense over the contractual term of the debt using the effective interest method. In accordance with ASC 470 20, Debt with Conversion and Other Options not 480, Distinguishing Liabilities from Equity 480”
Convertible Notes [Policy Text Block]	Convertible Debt In accordance with ASU 2020 06, Debt—Debt with Conversion and Other Options (Subtopic 470 20 815 40 not not not no 815, Derivatives and Hedging 815”
Lessee, Leases [Policy Text Block]	Leases At inception of a contract, we determine if a contract meets the definition of a lease. We determine if the contract conveys the right to control the use of an identified asset for a period of time. We assess throughout the period of use whether we have both of the following: (i) the right to obtain substantially all the economic benefits from use of the identified asset, and (ii) the right to direct the use of the identified asset. This determination is reassessed if the terms of the contract are changed. Leases are classified as operating or finance leases based on the terms of the lease agreement and certain characteristics of the identified asset. Right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of the future lease payments less any lease incentives received. At the lease commencement date, the discount rate implicit in the lease is used to discount the lease liability if readily determinable. If not not not twelve Certain lease agreements may not Leases may not
Contingent Earnout [Policy Text Block]	Contingent Earn-Out Liabilities In connection with the Reverse Recapitalization, certain Clene Nanomedicine stockholders are entitled to receive additional shares of Common Stock (the “Clene Nanomedicine Contingent Earn-out”) as follows: (i) 3,338,483 shares if (a) the volume-weighted average price (“VWAP”) of our Common Stock equals or exceeds $15.00 (the “Milestone 1 twenty thirty three 1 three 1” 2 twenty thirty five 2 five 2” 1 not 2 1. 1; 2. 1 not 2 1. In accordance with ASC 815, not
Common Stock Warrants [Policy Text Block]	Common Stock Warrants We account for common stock warrants as either equity- or liability-classified instruments based on an assessment of the warrant terms. The assessment considers whether the warrants are freestanding financial instruments pursuant to ASC 480, 480, 815,
Government Assistance [Policy Text Block]	Grant Funding We may 20, Accounting for Government Grants and Disclosure of Government Assistance 20” 4 We recognize grant funding with conditions or continuing performance obligations as a reduction in research and development expenses in the period during which the related qualifying expenses are incurred and as the conditions or performance obligations are fulfilled. Any amount received in advance of fulfilling such conditions or performance obligations is recorded in accrued liabilities (see Note 6 twelve three March 31, 2024 2023
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency Translation and Transactions Our functional and reporting currency is the U.S. dollar (“USD”). Clene Australia and Clene Netherlands determined their functional currencies to be the Australian dollar and Euro, respectively. The results of our foreign currency operations are translated into USD at the average exchange rates during the period, assets and liabilities are translated using the exchange rate as of the balance sheet date, and stockholders’ equity is translated using historical rates. Adjustments from the translation of the results of our foreign currency operations are excluded from net loss and are accumulated in a separate component of stockholders’ equity. We also incur foreign exchange transaction gains and losses for purchases denominated in foreign currencies. Foreign exchange transaction gains and losses are included in other income (expense), net, as incurred.
Comprehensive Income, Policy [Policy Text Block]	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The only elements of other comprehensive loss in any periods presented were the translation of foreign currency denominated balances of Clene Australia and Clene Netherlands to USD for consolidation and our unrealized gain (loss) on available-for-sale securities.
Segment Reporting, Policy [Policy Text Block]	Segment Information We report segment information based on ASC 280 Segment Reporting 280” may fourth 2023, 280, fourth 2023, two not
Income Tax, Policy [Policy Text Block]	Income Taxes We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the condensed consolidated financial statements or in our tax returns. Deferred tax assets and liabilities are determined based on the differences between the financial statement basis and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. We assess the likelihood that our deferred tax assets will be recovered from future taxable income and, to the extent we believe, based upon the weight of available evidence, that it is more likely than not not We account for uncertainty in income taxes recognized in the condensed consolidated financial statements by applying a two not may 50%
Share-Based Payment Arrangement [Policy Text Block]	Stock-Based Compensation We account for stock-based compensation arrangements using a fair value-based method for costs related to all share-based payments including stock options and stock awards. Stock-based compensation expense is recorded in research and development and general and administrative expenses based on the classification of the work performed by the grantees. The fair value is recognized over the period during which a grantee is required to provide services in exchange for the option award and service-based stock awards, known as the requisite service period (usually the vesting period), on a straight-line basis. For stock awards with market conditions, the fair value is recognized over the period based on the expected milestone achievement dates as the derived service period (usually the vesting period), on a straight-line basis. For stock awards with performance conditions, the grant-date fair value of these awards is the market price on the applicable grant date, and compensation expense will be recognized when the conditions become probable of being satisfied. We recognize a cumulative true-up adjustment once the conditions become probable of being satisfied as the related service period had been completed in a prior period. We elect to account for forfeitures as they occur, rather than estimating expected forfeitures. We determine the fair value of each share of Common Stock underlying stock-based awards using a Black-Scholes option pricing model based on the closing price of our Common Stock as reported by Nasdaq on the date of grant. The fair value of stock awards with market conditions are determined using a Monte Carlo valuation model.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements Not In November 2023, 2023 07, Segment Reporting (Topic 280 2023 07” 2023 07 280 2023 07, December 15, 2023, December 15, 2024. 2023 07. In December 2023, 2023 09, Income Taxes (Topic 740 2023 09” 2023 09 December 15, 2024. 2023 09.

Note 3 - Cash, Cash Equivalen_2

Note 3 - Cash, Cash Equivalents, and Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Cash and Cash Equivalents [Table Text Block]	March 31, 2024 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash equivalents (contractual maturity within 90 days): U.S. Treasury securities $ 12,192 $ — $ (1 ) $ 12,191 Money market funds 5,660 — — 5,660 Total cash equivalents 17,852 — (1 ) 17,851 Cash 3,881 — — 3,881 Total cash and cash equivalents $ 21,733 $ — $ (1 ) $ 21,732 Marketable securities (contractual maturity greater than 90 days but less than 1 year): U.S. Treasury securities $ 6,179 $ — $ (1 ) $ 6,178 Total marketable securities $ 6,179 $ — $ (1 ) $ 6,178 December 31, 2023 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash equivalents (contractual maturity within 90 days): U.S. Treasury securities $ 19,883 $ 1 $ — $ 19,884 Money market funds 5,113 — — 5,113 Total cash equivalents 24,996 1 — 24,997 Cash 3,824 — — 3,824 Total cash and cash equivalents $ 28,820 $ 1 $ — $ 28,821 Marketable securities (contractual maturity greater than 90 days but less than 1 year): U.S. Treasury securities $ 6,179 $ — $ — $ 6,179 Total marketable securities $ 6,179 $ — $ — $ 6,179

Note 4 - Prepaid Expenses and_2

Note 4 - Prepaid Expenses and Other Current Assets (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block]	March 31, December 31, (in thousands) 2024 2023 Metals to be used in research and development $ 1,826 $ 1,909 Research and development tax credits receivable 1,442 1,195 Other 832 568 Total prepaid expenses and other current assets $ 4,100 $ 3,672

Note 5 - Property and Equipme_2

Note 5 - Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Property, Plant and Equipment [Table Text Block]	March 31, December 31, (in thousands) 2024 2023 Lab equipment $ 4,065 $ 4,092 Office equipment 177 178 Computer software 459 459 Leasehold improvements 9,983 9,983 Construction in progress 1,449 1,438 16,133 16,150 Less accumulated depreciation (7,279 ) (6,887 ) Total property and equipment, net $ 8,854 $ 9,263
Depreciation Of Property Plant And Equipment [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 General and administrative $ 66 $ 67 Research and development 354 335 Total depreciation expense $ 420 $ 402

Note 6 - Accrued Liabilities (T

Note 6 - Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Accrued Liabilities [Table Text Block]	March 31, December 31, (in thousands) 2024 2023 Accrued compensation and benefits $ 2,628 $ 2,120 Accrued CRO and clinical fees 746 481 Other 531 1,119 Total accrued liabilities $ 3,905 $ 3,720

Note 7 - Leases (Tables)

Note 7 - Leases (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Assets Under Finance Lease [Table Text Block]	March 31, December 31, (in thousands) 2024 2023 Lab equipment $ 636 $ 636 Less accumulated depreciation (469 ) (449 ) Net $ 167 $ 187
Finance and Operating Lease Liability, Maturity [Table Text Block]	(in thousands) Finance Leases Operating Leases 2024 (remainder) $ 7 $ 789 2025 — 1,208 2026 — 1,236 2027 — 1,132 2028 — 1,093 2029 — 649 Thereafter — 1,045 Total minimum lease payments 7 7,152 Less amount representing interest/discounting — (1,833 ) Present value of minimum lease payments 7 5,319 Less lease obligations, current portion (7 ) (599 ) Lease obligations, net of current portion $ — $ 4,720
Lease, Cost [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 Finance lease costs: Amortization $ 27 $ 20 Interest on lease liabilities — 6 Operating lease costs 254 253 Variable lease costs 53 50 Total lease costs $ 334 $ 329
Schedule of Cash Flow, Supplemental Disclosures, Leases [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 Operating cash flows from operating leases $ (307 ) $ (303 ) Operating cash flows from finance leases $ — $ (6 ) Financing cash flows from finance leases $ (19 ) $ (28 )

Note 8 - Notes Payable and Co_2

Note 8 - Notes Payable and Convertible Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Long-Term Debt Instruments [Table Text Block]	Stated March 31, December 31, (in thousands, except interest rates) Interest Rate 2024 2023 Notes payable Advance Cecil, Inc. (commenced April 2019) 8.00 % $ 140 $ 138 Maryland DHCD (commenced February 2019) 8.00 % 704 694 Maryland DHCD (commenced May 2022) 6.00 % 1,083 1,083 Avenue Venture Opportunities Fund, L.P. (commenced May 2021) 15.10 % 15,000 15,000 16,927 16,915 Less unamortized discount and debt issuance costs (120 ) (394 ) Less notes payable, current portion, net of unamortized discount and debt issuance costs (14,987 ) (14,627 ) Total notes payable, net of current portion $ 1,820 $ 1,894 Convertible notes payable Avenue Venture Opportunities Fund, L.P. (commenced May 2021) 15.10 % $ 5,000 $ 5,000 Maryland DHCD (commenced December 2022) 6.00 % 5,388 5,308 10,388 10,308 Less unamortized discount and debt issuance costs (81 ) (174 ) Less convertible notes payable, current portion, net of unamortized discount and debt issuance costs (5,042 ) (4,876 ) Total convertible notes payable, net of current portion $ 5,265 $ 5,258
Schedule of Maturities of Long-Term Debt [Table Text Block]	(in thousands) 2019 MD Loan 2019 Cecil Loan 2021 Avenue Loan 2022 MD Loan 2022 DHCD Loan 2024 (remainder) $ — $ — $ 20,000 $ — $ — 2025 — — — 347 — 2026 — — — 369 — 2027 — — — 317 — 2028 — — — — 5,000 2029 — — — — — Thereafter 500 100 — — — Total debt principal payments 500 100 20,000 1,033 5,000 Accrued and unpaid interest 204 40 — 50 388 Less unamortized discount and debt issuance costs — — (134 ) (20 ) (47 ) Future debt payments, net $ 704 $ 140 $ 19,866 $ 1,063 $ 5,341

Note 10 - Income Taxes (Tables)

Note 10 - Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 United States $ (11,039 ) $ (11,546 ) Foreign (41 ) (224 ) Net loss before income taxes $ (11,080 ) $ (11,770 )

Note 11 - Benefit Plans (Tables

Note 11 - Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Share-Based Payment Arrangement, Cost by Plan [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 General and administrative $ 1,136 $ 1,250 Research and development 877 973 Total stock-based compensation expense $ 2,013 $ 2,223 Three Months Ended March 31, (in thousands) 2024 2023 Stock options $ 2,002 $ 2,222 Stock awards 11 1 Total stock-based compensation expense $ 2,013 $ 2,223
Share-Based Payment Arrangement, Option, Activity [Table Text Block]	(in thousands, except share, per share, and term data) Number of Options Weighted Average Exercise Price Per Share Weighted Average Remaining Term (Years) Intrinsic Value Outstanding – December 31, 2023 21,846,388 $ 2.26 7.28 $ 302 Granted 280,070 0.44 9.95 — Forfeited (141,124 ) 5.33 — — Outstanding – March 31, 2024 21,985,334 $ 2.22 7.07 $ 568 Vested and exercisable – March 31, 2024 12,511,524 $ 2.55 5.79 $ 567 Vested, exercisable or expected to vest – March 31, 2024 21,985,334 $ 2.22 7.07 $ 568
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	Three Months Ended March 31, 2024 2023 Expected stock price volatility 99.99 % 96.22% –103.24 % Risk-free interest rate 4.04 % 3.38% –3.98 % Expected dividend yield 0.00 % 0.00 % Expected term of options (in years) 5.00 5.00 –6.08
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]	Number of Stock Awards Weighted Average Grant Date Fair Value Unvested balance – December 31, 2023 778,815 $ 9.72 Converted to shares of Common Stock upon vesting (10,870 ) 1.15 Unvested balance – March 31, 2024 767,945 $ 9.84

Note 12 - Fair Value (Tables)

Note 12 - Fair Value (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	March 31, 2024 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: U.S. Treasury securities $ — $ 12,191 $ — $ 12,191 Money market funds 5,660 — — 5,660 Marketable securities: U.S. Treasury securities — 6,178 — 6,178 Common stock warrant liabilities — — 2,790 2,790 Clene Nanomedicine contingent earn-out liability — — 22 22 Initial Stockholders contingent earn-out liability — — 3 3 December 31, 2023 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: U.S. Treasury securities $ — $ 19,884 $ — $ 19,884 Money market funds 5,113 — — 5,113 Marketable securities: U.S. Treasury securities — 6,179 — 6,179 Common stock warrant liabilities — — 1,481 1,481 Clene Nanomedicine contingent earn-out liability — — 75 75 Initial Stockholders contingent earn-out liability — — 10 10 (in thousands) Common Stock Warrant Liabilities Clene Nanomedicine Contingent Earn-out Initial Stockholders Contingent Earn-out Balance – December 31, 2023 $ 1,481 $ 75 $ 10 Change in fair value 1,309 (53 ) (7 ) Balance – March 31, 2024 $ 2,790 $ 22 $ 3 (in thousands) Clene Nanomedicine Contingent Earn-out Initial Stockholders Contingent Earn-out Balance – December 31, 2022 $ 2,264 $ 291 Change in fair value 55 7 Balance – March 31, 2023 $ 2,319 $ 298
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	March 31, December 31, 2024 2023 Expected stock price volatility 105.00% – 120.00 % 105.00% – 110.00 % Risk-free interest rate 4.28% 5.38 % 3.88% 5.03 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 0.50 – 4.25 0.75 – 4.50 Probability of change of control 20.00 % 25.00 % Probability of dissolution 50.00 % 50.00 % Probability of other outcome 30.00 % 25.00 % March 31, December 31, 2024 2023 Expected stock price volatility 100.00% 105.00 % 100.00% 110.00 % Risk-free interest rate 4.55% 5.15 % 4.13% 4.74 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 0.83 2.21 1.08 2.46 Probability of NDA acceptance 20.00 % 20.00 % Probability of fundamental transaction 20.00 % 25.00 % Probability of dissolution 50.00 % 50.00 % Probability of other outcome 10.00 % 5.00 % March 31, December 31, 2024 2023 Expected stock price volatility 97.50 % 115.00 % Risk-free interest rate 4.70 % 4.20 % Expected dividend yield 0.00 % 0.00 % Expected term (in years) 1.75 2.00

Note 13 - Capital Stock (Tables

Note 13 - Capital Stock (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	Number of Shares Issuable March 31, December 31, Date Exercisable Exercise Price Expiration Classification 2024 2023 December 2020 $ 11.50 December 2025 (1) Equity 2,407,500 2,407,500 December 2020 $ 11.50 December 2025 (2) Equity 24,583 24,583 June 2023 $ 0.80 June 2028 (3) Liability 3,000,000 3,000,000 June 2023 $ 1.10 June 2026 (4) Liability 50,000,000 50,000,000 June 2023 $ 1.50 June 2030 (5) Equity 50,000,000 50,000,000 Total 105,432,083 105,432,083

Note 14 - Net Loss Per Share (T

Note 14 - Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended March 31, (in thousands, except share and per share data) 2024 2023 Numerator: Net loss attributable to common stockholders $ (11,080 ) $ (11,770 ) Denominator: Weighted average common shares outstanding 128,427,231 76,049,665 Net loss per share attributable to common stockholders – basic and diluted $ (0.09 ) $ (0.15 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three Months Ended March 31, 2024 2023 Convertible notes payable (see Note 8) 1,732,703 1,732,703 Common stock warrants (see Note 13) 105,432,083 4,477,045 Options to purchase common stock (see Note 11) 21,985,334 16,205,404 Unvested restricted stock awards (see Note 11) 767,945 812,170 Contingent earn-out shares (see Note 2) 6,592,334 6,592,334 Total 136,510,399 29,819,656

Note 15 - Related Party Trans_2

Note 15 - Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Schedule of Related Party Transactions [Table Text Block]	Three Months Ended March 31, (in thousands) 2024 2023 Product revenue from related parties $ 43 $ 63 Royalty revenue from related parties 29 43 Total revenue from related parties $ 72 $ 106

Note 1 - Nature of the Busine_2

Note 1 - Nature of the Business (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 30, 2020
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.0001		$ 0.0001	$ 0.0001
Operating Income (Loss)	$ (9,232)	$ (10,732)
Retained Earnings (Accumulated Deficit)	(253,803)		$ (242,723)
Cash, Cash Equivalents, and Short-Term Investments	27,900		35,000
Net Cash Provided by (Used in) Operating Activities	$ (7,082)	$ (9,218)
Minimum Cash Balance For Loan Covenant			$ 5,000

Note 2 - Summary of Significa_2

Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Inventory, Raw Materials, Gross	$ 23,000		$ 23,000
Inventory, Finished Goods, Gross	14,000		$ 14,000
Research and Development Expense	5,869,000	$ 7,395,000
Grant Funding on Conditional Grants [Member]
Research and Development Expense	$ 300,000	$ 0
Reverse Recapitalization [Member] | Clene Nanomedicine Contingent Earn-out [Member]
Business Combination, Contingent Earnout Shares, Milestone One (in shares)	3,338,483
Business Combination, Contingent Earnout, Milestone One, Minimum Price (in dollars per share)	$ 15
Business Combination, Contingent Earnout, Milestone One, Consecutive Trading Days (Day)	20 days
Business Combination, Contingent Earnout, Milestone One, Trading Day Period (Day)	30 days
Business Combination, Contingent Earnout, Milestone One, Period (Year)	3 years
Business Combination, Contingent Earnout Shares, Milestone Two (in shares)	2,503,851
Business Combination, Contingent Earnout, Milestone Two, Minimum Price (in dollars per share)	$ 20
Business Combination, Contingent Earnout, Milestone Two, Consecutive Trading Days (Day)	20 days
Business Combination, Contingent Earnout, Milestone Two, Trading Day Period (Day)	30 days
Business Combination, Contingent Earnout, Milestone Two, Period (Year)	5 years
Business Combination, Contingent Earnout, Milestone Two, Change of Control Period (Year)	5 years
Reverse Recapitalization [Member] | Initial Stockholders Contingent Earn-out [Member]
Business Combination, Contingent Earnout Shares, Milestone One (in shares)	375,000
Business Combination, Contingent Earnout Shares, Milestone Two (in shares)	375,000
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	3 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	7 years
Computer Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Computer Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years

Note 3 - Cash, Cash Equivalen_3

Note 3 - Cash, Cash Equivalents, and Marketable Securities (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Proceeds from Sale and Maturity of Marketable Securities	$ 6,300	$ 5,000
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0

Note 3 - Cash, Cash Equivalen_4

Note 3 - Cash, Cash Equivalents, and Marketable Securities - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
US Treasury Securities [Member]
Amortized cost	$ 12,192	$ 19,883
Gross unrealized gains	0	1
Gross unrealized losses	(1)	0
Fair value	12,191	19,884
Money Market Funds [Member]
Amortized cost	5,660	5,113
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	5,660	5,113
Cash Equivalents [Member]
Amortized cost	17,852	24,996
Gross unrealized gains	0	1
Gross unrealized losses	(1)	0
Fair value	17,851	24,997
Cash [Member]
Amortized cost	3,881	3,824
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	3,881	3,824
Cash and Cash Equivalents [Member]
Amortized cost	21,733	28,820
Gross unrealized gains	0	1
Gross unrealized losses	(1)	0
Fair value	21,732	28,821
Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Amortized cost	6,179	6,179
Gross unrealized gains	0	0
Gross unrealized losses	(1)	0
Fair value	6,178	6,179
Marketable Securities [Member]
Amortized cost	6,179	6,179
Gross unrealized gains	0	0
Gross unrealized losses	(1)	0
Fair value	$ 6,178	$ 6,179

Note 4 - Prepaid Expenses and_3

Note 4 - Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Metals to be used in research and development	$ 1,826	$ 1,909
Research and development tax credits receivable	1,442	1,195
Other	832	568
Total prepaid expenses and other current assets	$ 4,100	$ 3,672

Note 5 - Property and Equipme_3

Note 5 - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property and equipment, gross	$ 16,133	$ 16,150
Less accumulated depreciation	(7,279)	(6,887)
Total property and equipment, net	8,854	9,263
Equipment [Member]
Property and equipment, gross	4,065	4,092
Office Equipment [Member]
Property and equipment, gross	177	178
Computer Equipment [Member]
Property and equipment, gross	459	459
Leasehold Improvements [Member]
Property and equipment, gross	9,983	9,983
Construction in Progress [Member]
Property and equipment, gross	$ 1,449	$ 1,438

Note 5 - Property and Equipme_4

Note 5 - Property and Equipment, Net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Depreciation	$ 420	$ 402
General and Administrative Expense [Member]
Depreciation	66	67
Research and Development Expense [Member]
Depreciation	$ 354	$ 335

Note 6 - Accrued Liabilities -

Note 6 - Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accrued compensation and benefits	$ 2,628	$ 2,120
Accrued CRO and clinical fees	746	481
Other	531	1,119
Total accrued liabilities	$ 3,905	$ 3,720

Note 7 - Leases (Details Textua

Note 7 - Leases (Details Textual)	1 Months Ended
	Sep. 30, 2022	Feb. 28, 2022	Sep. 30, 2021	Mar. 31, 2024	Dec. 31, 2023
Number of Real Estate Leases				3
Operating Lease, Weighted Average Discount Rate, Percent				9.60%	9.60%
Operating Lease, Weighted Average Remaining Lease Term (Year)				6 years 1 month 6 days	6 years 4 months 24 days
Finance Lease, Weighted Average Discount Rate, Percent				11%	11%
Finance Lease, Weighted Average Remaining Lease Term (Year)				1 month 6 days	4 months 24 days
Lease for Laboratory Space [Member]
Lessee, Operating Lease, Term of Contract (Year)		7 years	10 years
Lessee, Operating Lease, Option To Extend Period (Year)	5 years	10 years	10 years
Lessee, Operating Lease, Renewal Term (Year)	7 years

Note 7 - Leases - Assets Record

Note 7 - Leases - Assets Recorded Under Finance Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Less accumulated depreciation	$ (469)	$ (449)
Net	167	187
Equipment [Member]
Finance lease asset, gross	$ 636	$ 636

Note 7 - Leases - Maturity Anal

Note 7 - Leases - Maturity Analysis of Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
2024 (remainder), finance leases	$ 7
2024 (remainder), operating leases	789
2025, finance leases	0
2025, operating leases	1,208
2026, finance leases	0
2026, operating leases	1,236
2027, finance leases	0
2027, operating leases	1,132
2028, finance leases	0
2028, operating leases	1,093
2029, finance leases	0
2029, operating leases	649
Thereafter, finance leases	0
Thereafter, operating leases	1,045
Total minimum lease payments, finance leases	7
Total minimum lease payments, operating leases	7,152
Less amount representing interest/discounting, finance leases	0
Less amount representing interest/discounting, operating leases	(1,833)
Present value of minimum lease payments, finance leases	7
Present value of minimum lease payments, operating leases	5,319
Less lease obligations, current portion, finance leases	7	$ 27
Less lease obligations, current portion, operating leases	599	576
Lease obligations, net of current portion, finance leases	0
Lease obligations, net of current portion, operating leases	$ 4,720	$ 4,903

Note 7 - Leases - Components of

Note 7 - Leases - Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Amortization	$ 27	$ 20
Interest on lease liabilities	0	6
Operating lease costs	254	253
Variable lease costs	53	50
Total lease costs	$ 334	$ 329

Note 7 - Leases - Supplemental

Note 7 - Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating cash flows from operating leases	$ (307)	$ (303)
Operating cash flows from finance leases	0	(6)
Payments of finance lease obligations	$ (19)	$ (28)

Note 8 - Notes Payable and Co_3

Note 8 - Notes Payable and Convertible Notes Payable (Details Textual) - USD ($)			1 Months Ended					3 Months Ended
	Apr. 30, 2019	Feb. 28, 2019	Jun. 30, 2023	Dec. 31, 2022	May 31, 2022	Sep. 30, 2021	May 31, 2021	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Proceeds from Notes Payable, Total								$ 0		$ 350,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)								105,432,083	105,432,083
New Avenue Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									3,000,000
Avenue [Member] | Warrants Issued with 2021 Avenue Loan [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)							115,851
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)							$ 8.63
Warrants and Rights Outstanding							$ 1,500,000
Avenue [Member] | New Avenue Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)							3,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)							$ 0.8
Warrants and Rights Outstanding							$ 700,000
Avenue [Member] | Minimum [Member] | Public Equity Offering [Member]
Equity Milestone 1 Condition for Extended Interest Only Period			$ 35,000,000
Equity Milestone 2 Condition for Extended Interest Only Period			$ 40,000,000
The 2019 MD Loan [Member] | Department of Housing and Community Development [Member]
Debt Instrument, Face Amount		$ 500,000
Debt Instrument, Interest Rate, Stated Percentage		8%
Phantom Shares for Potential Repayment (in shares)		119,907
Interest Expense, Debt								$ 10,000		10,000
The 2019 Cecil Loan [Member] | Advance Cecil Inc. [Member]
Debt Instrument, Face Amount	$ 100,000
Debt Instrument, Interest Rate, Stated Percentage	8%
Phantom Shares for Potential Repayment (in shares)	23,981
Interest Expense, Debt								2,000		2,000
The 2022 MD Loan [Member] | Department of Housing and Community Development [Member]
Debt Instrument, Face Amount					$ 3,000,000
Debt Instrument, Interest Rate, Stated Percentage					6%
Interest Expense, Debt								15,000		12,000
Proceeds from Loans								1,000,000
Debt Instrument, Monthly Interest-only Payments, Maximum Amount, First Eighteen Installments					$ 15,000
Debt Instrument, Monthly Principal and Interest Payment, for the Next Thirty Installments					33,306
Interest Payable								$ 50,000	$ 50,000
Debt Issuance Costs, Gross					$ 31,000
The 2022 DHCD Loan [Member] | Convertible Notes Payable [Member]
Debt Instrument, Interest Rate, Stated Percentage								6%
The 2022 DHCD Loan [Member] | Department of Housing and Community Development [Member]
Debt Instrument, Face Amount				$ 5,000,000
Debt Instrument, Interest Rate, Stated Percentage				6%
Interest Expense, Debt								$ 100,000		100,000
Interest Payable								400,000	$ 300,000
Debt Issuance Costs, Gross				$ 100,000
Debt Instrument, Convertible, Minimum Increment of Principal for Exercise				$ 1,000,000
Debt Conversion, Conversion Price, Percent of 30-day Trailing Volume-weighted Average Sale Price of Common Stock				97%
Debt Instrument, Convertible, Conversion Price (in dollars per share)				$ 4
Coupon Interest Expense								100,000		100,000
Amortization of Debt Issuance Costs and Discounts								$ 3,000		3,000
Debt Instrument, Interest Rate, Effective Percentage								5.99%
The 2021 Avenue Loan [Member] | Avenue [Member]
Debt Instrument, Face Amount							$ 30,000,000
Debt Instrument, Interest Rate, Stated Percentage							3.25%
Interest Expense, Debt								$ 1,100,000		1,000,000
Debt Instrument, Convertible, Conversion Price (in dollars per share)								$ 10.36
Debt Instrument, Basis Spread on Variable Rate							6.60%
Debt Instrument, Interest Rate During Period								15.10%	14.10%
Debt Issuance Costs, Net							$ 800,000
Debt Issuance Costs Expensed							$ 47,000
Debt Instrument, Interest Only Payments, Period (Month)							12 months
Debt Instrument, First Interest-only Period Extension (Month)							12 months
Additional Payment at Debt Maturity, Percentage of Principal							4.25%
Additional Payment at Debt Maturity							$ 900,000
Debt Instrument, Convertible, Maximum Conversion Amount								$ 5,000,000
Debt Instrument, Covenant, Cash and Certain Cash Equivalents, Minimum								5,000,000
The 2021 Avenue Loan [Member] | Avenue [Member] | Convertible Notes Payable [Member]
Interest Expense, Debt								300,000		200,000
Coupon Interest Expense								200,000		200,000
Amortization of Debt Issuance Costs and Discounts								$ 100,000		$ 100,000
Debt Instrument, Interest Rate During Period								22.79%		20.17%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net								$ 33,000	$ 100,000
The 2021 Avenue Loan [Member] | Avenue [Member] | Notes Payable, Tranche 1 [Member]
Proceeds from Notes Payable, Total						$ 5,000,000	15,000,000
The 2021 Avenue Loan [Member] | Avenue [Member] | Notes Payable, Tranche 2 [Member]
Debt Instrument, Unfunded Balance							$ 10,000,000

Note 8 - Notes Payable and Co_4

Note 8 - Notes Payable and Convertible Notes Payable - Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Future debt payments, net	$ 16,927	$ 16,915
Less notes payable, current portion, net of unamortized discount and debt issuance costs	(14,987)	(14,627)
Notes payable, net of current portion	1,820	1,894
Notes payable	16,927	16,915
Convertible notes payable, net of current portion	5,265	5,258
Notes Payable [Member]
Less unamortized discount and debt issuance costs	(120)	(394)
Less notes payable, current portion, net of unamortized discount and debt issuance costs	(14,987)	(14,627)
Notes payable, net of current portion	1,820	1,894
Convertible Notes Payable [Member]
Future debt payments, net	10,388	10,308
Notes payable	10,388	10,308
Less unamortized discount and debt issuance costs	(81)	(174)
Less convertible notes payable, current portion, net of unamortized discount and debt issuance costs	(5,042)	(4,876)
Convertible notes payable, net of current portion	$ 5,265	5,258
The 2019 Cecil Loan [Member] | Notes Payable [Member]
Interest Rate	8%
Future debt payments, net	$ 140	138
Notes payable	$ 140	138
The 2019 Maryland DHCD [Member] | Notes Payable [Member]
Interest Rate	8%
Future debt payments, net	$ 704	694
Notes payable	$ 704	694
The 2022 Maryland DHCD [Member] | Notes Payable [Member]
Interest Rate	6%
Future debt payments, net	$ 1,083	1,083
Notes payable	$ 1,083	1,083
Avenue [Member] | Notes Payable [Member]
Interest Rate	15.10%
Future debt payments, net	$ 15,000	15,000
Notes payable	$ 15,000	15,000
Avenue [Member] | Convertible Notes Payable [Member]
Interest Rate	15.10%
Future debt payments, net	$ 5,000	5,000
Notes payable	5,000	5,000
The 2022 DHCD Loan [Member] | Notes Payable [Member]
Future debt payments, net	5,341
Notes payable	$ 5,341
The 2022 DHCD Loan [Member] | Convertible Notes Payable [Member]
Interest Rate	6%
Future debt payments, net	$ 5,388	5,308
Notes payable	$ 5,388	$ 5,308

Note 8 - Notes Payable and Co_5

Note 8 - Notes Payable and Convertible Notes Payable - Schedule of Future Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Future debt payments, net	$ 16,927	$ 16,915
The 2019 MD Loan [Member] | Notes Payable [Member]
2024 (remainder)	0
2025	0
2026	0
2027	0
2028	0
2029	0
Thereafter	500
Total debt principal payments	500
Accrued and unpaid interest	204
Less unamortized discount and debt issuance costs	0
Future debt payments, net	704
The 2019 Cecil Loan [Member] | Notes Payable [Member]
2024 (remainder)	0
2025	0
2026	0
2027	0
2028	0
2029	0
Thereafter	100
Total debt principal payments	100
Accrued and unpaid interest	40
Less unamortized discount and debt issuance costs	0
Future debt payments, net	140	$ 138
The 2021 Avenue Loan [Member] | Notes Payable [Member]
2024 (remainder)	20,000
2025	0
2026	0
2027	0
2028	0
2029	0
Thereafter	0
Total debt principal payments	20,000
Accrued and unpaid interest	0
Less unamortized discount and debt issuance costs	(134)
Future debt payments, net	19,866
The 2022 MD Loan [Member] | Notes Payable [Member]
2024 (remainder)	0
2025	347
2026	369
2027	317
2028	0
2029	0
Thereafter	0
Total debt principal payments	1,033
Accrued and unpaid interest	50
Less unamortized discount and debt issuance costs	(20)
Future debt payments, net	1,063
The 2022 DHCD Loan [Member] | Notes Payable [Member]
2024 (remainder)	0
2025	0
2026	0
2027	0
2028	5,000
2029	0
Thereafter	0
Total debt principal payments	5,000
Accrued and unpaid interest	388
Less unamortized discount and debt issuance costs	(47)
Future debt payments, net	$ 5,341

Note 9 - Commitments and Cont_2

Note 9 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	May 31, 2023	Sep. 30, 2019	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Government Assistance, Amount			$ 286	$ 314
Grant Funding Related to VISIONARY-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member]
Government Assistance, Amount		$ 300
Government Assistance, Repayment, Percentage of Grant Funding Upon First Commercial Product Sale		50%
Government Assistance, Repayment, Additional Percentage of Grant Funding, Tranche One		50%
Government Assistance, Repayment, Cumulative Sales, Tranche One		$ 10,000
Government Assistance, Repayment, Cumulative Sales, Tranche Two		$ 50,000
Government Assistance, Repayment, Additional Percentage of Grant Funding, Tranche Three		200%
Government Assistance, Repayment, Cumulative Sales, Tranche Three		$ 100,000
Government Assistance, Repayment, Maximum Percentage of Grant Funding When All Milestones Achieved		450%
Government Assistance, Aggregate Repayment, Percentage of Grant Funding		300%
Government Assistance, Repayment, Percentage of Grant Funding Upon Closing		300%
Government Assistance, Repayment Amount Upon Closing		$ 1,000
Grant Funding Related to VISIONARY-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member] | Minimum [Member]
Government Assistance, Possible Loss, Percentage of Grant Funding		50%
Government Assistance, Possible Loss Between Minimum and Maximum Repayment Amounts		$ 200
Grant Funding Related to VISIONARY-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member] | Maximum [Member]
Government Assistance, Possible Loss, Percentage of Grant Funding		450%
Government Assistance, Possible Loss Between Minimum and Maximum Repayment Amounts		$ 1,500
Grant Funding Related to REPAIR-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member]
Government Assistance, Amount	$ 700
Government Assistance, Repayment, Additional Percentage of Grant Funding, Tranche Two		150%
Government Assistance, Aggregate Repayment, Percentage of Grant Funding	150%
Government Assistance, Repayment, Percentage of Grant Funding Upon Closing	150%
Government Assistance, Repayment Amount Upon Closing	$ 1,000
Grant Funding Related to REPAIR-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member] | Minimum [Member]
Government Assistance, Possible Loss Between Minimum and Maximum Repayment Amounts	300
Grant Funding Related to REPAIR-MS Phase 2 Clinical Trial [Member] | National Multiple Sclerosis Society [Member] | Maximum [Member]
Government Assistance, Possible Loss Between Minimum and Maximum Repayment Amounts	$ 3,000
Capital Addition Purchase Commitments [Member]
Long-Term Purchase Commitment, Amount			$ 200		$ 400

Note 10 - Income Taxes - Compon

Note 10 - Income Taxes - Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
United States	$ (11,039)	$ (11,546)
Foreign	(41)	(224)
Net loss before income taxes	$ (11,080)	$ (11,770)

Note 11 - Benefit Plans (Detail

Note 11 - Benefit Plans (Details Textual) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	May 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number (in shares)	21,985,334		21,846,388
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)	280,070
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 0		$ 11,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			2 months 23 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 0.34	$ 0.99
Share-Based Payment Arrangement, Option [Member]
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 11,700,000		$ 13,700,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	1 year 11 months 1 day		2 years 1 month 6 days
The 2014 Stock Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number (in shares)	5,357,359
The 2020 Stock Plan [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)				18,400,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)	17,722,653
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)	677,347
The 401(k) Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	3%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount	$ 4,500
Defined Contribution Plan, Cost	$ 100,000	$ 100,000

Note 11 - Benefit Plans - Stock

Note 11 - Benefit Plans - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total stock-based compensation expense	$ 2,013	$ 2,223
Share-Based Payment Arrangement, Option [Member]
Total stock-based compensation expense	2,002	2,222
Restricted Stock Awards [Member]
Total stock-based compensation expense	11	1
General and Administrative Expense [Member]
Total stock-based compensation expense	1,136	1,250
Research and Development Expense [Member]
Total stock-based compensation expense	$ 877	$ 973

Note 11 - Benefit Plans - Activ

Note 11 - Benefit Plans - Activity Related to Outstanding Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Beginning balance outstanding, number of options (in shares)	21,846,388
Beginning balance outstanding, weighted average exercise price per share (in dollars per share)	$ 2.26
Outstanding, weighted average remaining term (Year)	7 years 25 days	7 years 3 months 10 days
Outstanding, intrinsic value	$ 302
Granted, number of options (in shares)	280,070
Granted, weighted average exercise price per share (in dollars per share)	$ 0.44
Granted, weighted average remaining term (Year)	9 years 11 months 12 days
Forfeited, number of options (in shares)	(141,124)
Forfeited, weighted average exercise price per share (in dollars per share)	$ 5.33
Ending balance outstanding, number of options (in shares)	21,985,334	21,846,388
Ending balance outstanding, weighted average exercise price per share (in dollars per share)	$ 2.22	$ 2.26
Outstanding, intrinsic value	$ 568	$ 302
Vested and exercisable, number of options (in shares)	12,511,524
Vested and exercisable, weighted average exercise price per share (in dollars per share)	$ 2.55
Vested and exercisable, weighted average remaining term (Year)	5 years 9 months 14 days
Vested and exercisable, intrinsic value	$ 567
Vested, exercisable and expected to vest, number of options (in shares)	21,985,334
Vested, exercisable and expected to vest, weighted average exercise price per share (in dollars per share)	$ 2.22
Vested, exercisable or expected to vest, weighted average remaining term (Year)	7 years 25 days
Vested, exercisable or expected to vest, intrinsic value	$ 568

Note 11 - Benefit Plans - Assum

Note 11 - Benefit Plans - Assumptions of Stock Options (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Expected stock price volatility	99.99%
Risk-free interest rate	4.04%
Expected dividend yield	0%	0%
Expected term of options (in years) (Year)	5 years
Minimum [Member]
Expected stock price volatility		96.22%
Risk-free interest rate		3.38%
Expected term of options (in years) (Year)		5 years
Maximum [Member]
Expected stock price volatility		103.24%
Risk-free interest rate		3.98%
Expected term of options (in years) (Year)		6 years 29 days

Note 11 - Benefit Plans - Act_2

Note 11 - Benefit Plans - Activity Related to Restricted Stock Awards (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Converted to shares of Common Stock upon vesting, number of restricted stock awards (in shares) | shares	(10,870)
Converted to shares of Common Stock upon vesting, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.15
Restricted Stock [Member]
Unvested balance, number of restricted stock awards (in shares) | shares	778,815
Unvested balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 9.72
Unvested balance, number of restricted stock awards (in shares) | shares	767,945
Unvested balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 9.84

Note 12 - Fair Value - Assets a

Note 12 - Fair Value - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Clene Nanomedicine contingent earn-out liability	$ 22		$ 75
Initial Stockholders contingent earn-out liability	3		10
Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	6,178		6,179
US Treasury Securities [Member]
Cash Equivalents	12,191		19,884
Money Market Funds [Member]
Cash Equivalents	5,660		5,113
Fair Value, Inputs, Level 1 [Member]
Clene Nanomedicine contingent earn-out liability	0		0
Initial Stockholders contingent earn-out liability	0		0
Fair Value, Inputs, Level 1 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	0		0
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Cash Equivalents	5,660		5,113
Fair Value, Inputs, Level 2 [Member]
Clene Nanomedicine contingent earn-out liability	0		0
Initial Stockholders contingent earn-out liability	0		0
Fair Value, Inputs, Level 2 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	6,178		6,179
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Cash Equivalents	12,191		19,884
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 3 [Member]
Clene Nanomedicine contingent earn-out liability	22		75
Initial Stockholders contingent earn-out liability	3		10
Fair Value, Inputs, Level 3 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	0		0
Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Cash Equivalents	0		0
Common Stock Warrant Liability [Member]
Common stock warrant liabilities	2,790		1,481
Balance	1,481
Change in fair value	1,309
Balance	2,790
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 1 [Member]
Common stock warrant liabilities	0		0
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 2 [Member]
Common stock warrant liabilities	0		0
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Common stock warrant liabilities	2,790		$ 1,481
Clene Nanomedicine Contingent Earn-out [Member]
Balance	75	$ 2,264
Change in fair value	(53)	55
Balance	22	2,319
Initial Stockholders Contingent Earn-out [Member]
Balance	10	291
Change in fair value	(7)	7
Balance	$ 3	$ 298

Note 12 - Fair Value - Unobserv

Note 12 - Fair Value - Unobservable Inputs (Details)	Mar. 31, 2024	Dec. 31, 2023
New Avenue Warrant [Member] | Measurement Input, Price Volatility [Member] | Minimum [Member]
Derivative, measurement input	1.05	1.05
New Avenue Warrant [Member] | Measurement Input, Price Volatility [Member] | Maximum [Member]
Derivative, measurement input	1.20	1.10
New Avenue Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]
Derivative, measurement input	0.0428	0.0388
New Avenue Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]
Derivative, measurement input	0.0538	0.0503
New Avenue Warrant [Member] | Measurement Input, Expected Dividend Rate [Member]
Derivative, measurement input	0	0
New Avenue Warrant [Member] | Measurement Input, Expected Term [Member] | Minimum [Member]
Derivative, measurement input	0.5	0.75
New Avenue Warrant [Member] | Measurement Input, Expected Term [Member] | Maximum [Member]
Derivative, measurement input	4.25	4.5
New Avenue Warrant [Member] | Measurement Input, Probability of Change of Control [Member]
Derivative, measurement input	0.20	0.25
New Avenue Warrant [Member] | Measurement Input, Probability of Dissolution [Member]
Derivative, measurement input	0.50	0.50
New Avenue Warrant [Member] | Measurement Input, Probability of Other Outcome [Member]
Derivative, measurement input	0.30	0.25
Tranche A Warrant [Member] | Measurement Input, Price Volatility [Member] | Minimum [Member]
Derivative, measurement input	1	1
Tranche A Warrant [Member] | Measurement Input, Price Volatility [Member] | Maximum [Member]
Derivative, measurement input	1.05	1.10
Tranche A Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]
Derivative, measurement input	0.0455	0.0413
Tranche A Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]
Derivative, measurement input	0.0515	0.0474
Tranche A Warrant [Member] | Measurement Input, Expected Dividend Rate [Member]
Derivative, measurement input	0	0
Tranche A Warrant [Member] | Measurement Input, Expected Term [Member] | Minimum [Member]
Derivative, measurement input	0.83	1.08
Tranche A Warrant [Member] | Measurement Input, Expected Term [Member] | Maximum [Member]
Derivative, measurement input	2.21	2.46
Tranche A Warrant [Member] | Measurement Input, Probability of NDA Acceptance [Member]
Derivative, measurement input	0.20	0.20
Tranche A Warrant [Member] | Measurement Input, Probability of Dissolution [Member]
Derivative, measurement input	0.50	0.50
Tranche A Warrant [Member] | Measurement Input, Probability of Fundamental Transaction [Member]
Derivative, measurement input	0.20	0.25
Tranche A Warrant [Member] | Measurement Input, Probability of Other Outcome [Member]
Derivative, measurement input	0.10	0.05
Contingent Earnout Shares [Member] | Measurement Input, Price Volatility [Member]
Derivative, measurement input	0.975	1.15
Contingent Earnout Shares [Member] | Measurement Input, Risk Free Interest Rate [Member]
Derivative, measurement input	0.047	0.042
Contingent Earnout Shares [Member] | Measurement Input, Expected Dividend Rate [Member]
Derivative, measurement input		0
Contingent Earnout Shares [Member] | Measurement Input, Expected Dividend Rate [Member] | Minimum [Member]
Derivative, measurement input	0
Contingent Earnout Shares [Member] | Measurement Input, Expected Term [Member]
Derivative, measurement input	1.75	2

Note 13 - Capital Stock (Detail

Note 13 - Capital Stock (Details Textual) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended			12 Months Ended
	May 08, 2024	Mar. 03, 2023	Dec. 30, 2020	Jun. 30, 2023	Dec. 31, 2022	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2023
Common Stock, Shares Authorized (in shares)						300,000,000	300,000,000		300,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.0001			$ 0.0001	$ 0.0001		$ 0.0001
Preferred Stock, Shares Authorized (in shares)						1,000,000	1,000,000		1,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)						$ 0.0001	$ 0.0001		$ 0.0001
Common Stock, Shares, Issued (in shares)						128,433,721	128,422,851		128,422,851
Preferred Stock, Shares Issued (in shares)						0	0		0
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)						105,432,083	105,432,083		105,432,083
Common Stock, Shares, Outstanding (in shares)						128,433,721	128,422,851		128,422,851
Preferred Stock, Shares Outstanding (in shares)						0	0		0
ATM Facility [Member]
Aggregate Offering Price					$ 50,000
Fixed Commission Rate Percentage						3%
Stock Issued During Period, Shares, New Issues (in shares)						0	2,895,090
Proceeds from Issuance of Common Stock								$ 4,500
Payments for Commissions								$ 100
ATM Facility [Member] | Subsequent Event [Member]
Aggregate Offering Price	$ 12,300
Canaccord [Member] | Underwriting Agreement [Member]
Unit Issued During Period, Units, New Issues (in shares)				50,000,000
Unit Issued, Price Per Unit (in dollars per share)				$ 0.8
Each Unit, Number of Common Stock (in shares)				1
Proceeds from Issuance or Sale of Equity				$ 40,000
Payment for Underwriting Fees and Commissions				2,400
Payments of Stock Issuance Costs				200
Gain (Loss) on Issuance of Equity				$ (14,800)
Lincoln Park Capital Fund, LLC [Member]
Stock Issued During Period, Shares, New Issues (in shares)		332,668
Purchase Agreement, Commencing Period (Month)		36 months
Purchase Agreement, Regular Purchase (in shares)		75,000
Purchase Agreement, Regular Purchase, Shares, Closing Price One (in shares)		100,000
Purchase Agreement, Closing Price One (in dollars per share)		$ 1
Purchase Agreement, Regular Purchase, Shares, Closing Price Two (in shares)		150,000
Purchase Agreement, Closing Price Two (in dollars per share)		$ 2
Purchase Agreement, Regular Purchase, Shares, Closing Price Three (in shares)		200,000
Purchase Agreement, Closing Price Three (in dollars per share)		$ 4
Purchase Agreement, Accelerated Purchase, Maximum Percentage of Regular Purchase		300%
Purchase Agreement, Accelerated Purchase, Maximum Percentage Of Prior Day Volume		30%
Purchase Agreement, Additional Accelerated Purchase, Maximum Percentage of Regular Purchase		300%
Purchase Agreement, Additional Accelerated Purchase, Maximum Percentage of Prior Day Volume		30%
Purchase Agreement, Price Discount of Additional Purchases		97%
Purchase Agreement, Additional Commitment Shares (in shares)		166,334
Purchase Agreement, Shares Sell Limitation (in shares)		15,310,115
Purchase Agreement, Shares Sell Limitation, Percentage Of Outstanding Shares		19.99%
Percentage of Common Stock Beneficial Ownership		4.99%
Derivative, Notional Amount						$ 0	$ 0		$ 0
Lincoln Park Capital Fund, LLC [Member] | Maximum [Member]
Purchase Agreement, Amount Of Shares Commit To Purchase		$ 25,000
Percentage of Common Stock Beneficial Ownership		9.99%
Lincoln Park Capital Fund, LLC [Member] | Minimum [Member]
Purchase Agreement, Minimum Average Price Per Share To Avoid Sell Limitation (in dollars per share)		$ 1.2404
Lincoln Park [Member] | Purchase Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)						0		0
Warrants Originally Issued by Tottenham Acquisition I Limited [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			2,407,500
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)			0.5
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 0.01
Class of Warrant or Right, Redemption, Threshold Stock Price Trigger (in dollars per share)			$ 16.5
Class of Warrant or Right, Redemption, Threshold Consecutive Trading Days (Day)			20 days
Class of Warrant or Right, Redemption, Threshold Trading Days (Day)			30 days
Class of Warrant or Right, Exercised During Period (in shares)						0			0
Chardan Unit Purchase Option [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			24,583
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)			0.5
Class of Warrant or Right, Exercised During Period (in shares)						0			0
New Avenue Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)							3,000,000		3,000,000
Class of Warrant or Right, Exercised During Period (in shares)						0			0
Tranche A Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				50,000,000
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)				1
Class of Warrant or Right, Exercised During Period (in shares)						0			0
Tranche A Warrant [Member] | Canaccord [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)				1
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 1.1
Each Unit, Number of Warrant (in shares)				1
Tranche B Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				50,000,000
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)				1
Class of Warrant or Right, Exercised During Period (in shares)						0			0
Tranche B Warrant [Member] | Canaccord [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)				1
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 1.5
Each Unit, Number of Warrant (in shares)				1

Note 13 - Capital Stock - Outst

Note 13 - Capital Stock - Outstanding Warrants (Details) - $ / shares		Mar. 31, 2024	Dec. 31, 2023
Number of shares issuable (in shares)		105,432,083	105,432,083
Common Stock Warrant Exercisable on December 2020, One [Member]
Exercise price (in dollars per share)		$ 11.5
Number of shares issuable (in shares)	[1]	2,407,500	2,407,500
Common Stock Warrant Exercisable on December 2020, Two [Member]
Exercise price (in dollars per share)		$ 11.5
Number of shares issuable (in shares)	[2]	24,583	24,583
Common Stock Warrant Exercisable on June 2023, One [Member]
Exercise price (in dollars per share)		$ 0.8
Number of shares issuable (in shares)	[3]	3,000,000	3,000,000
Common Stock Warrant Exercisable on June 2023, Two [Member]
Exercise price (in dollars per share)		$ 1.1
Number of shares issuable (in shares)	[4]	50,000,000	50,000,000
Common Stock Warrant Exercisable on June 2023, Three [Member]
Exercise price (in dollars per share)		$ 1.5
Number of shares issuable (in shares)	[5]	50,000,000	50,000,000
[1]Represents 2,407,500 shares of Common Stock underlying warrants to purchase one-half (1/2) of one share of Common Stock, issued during Tottenham’s initial public offering. We may redeem the outstanding warrants at $0.01 per warrant if the last sales price of our Common Stock equals or exceeds $16.50 per share for any 20 trading days within a 30-trading day period. As of March 31, 2024 and December 31, 2023, no warrants had been exercised.[2]Represents 24,583 shares of Common Stock underlying warrants to purchase one-half (1/2) of one share of Common Stock, issued to the financial advisor and lead underwriter of Tottenham’s initial public offering upon their exercise of a unit purchase option in July 2021. As of March 31, 2024 and December 31, 2023, no warrants had been exercised.[3]Represents 3,000,000 shares of Common Stock underlying the New Avenue Warrant, issued pursuant to the Second Amendment (see Note 8). As of March 31, 2024 and December 31, 2023, the warrant had not been exercised.[4]Represents 50,000,000 shares of Common Stock underlying the Tranche A Warrants to purchase one share of Common Stock, issued in our June 2023 public equity offering. As of March 31, 2024 and December 31, 2023, no warrants had been exercised.[5]Represents 50,000,000 shares of Common Stock underlying the Tranche B Warrants to purchase one share of Common Stock, issued in our June 2023 public equity offering. As of March 31, 2024 and December 31, 2023, no warrants had been exercised.

Note 14 - Net Loss Per Share -

Note 14 - Net Loss Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net loss	$ (11,080)	$ (11,770)
Weighted average common shares used to compute basic and diluted net loss per share (in shares)	128,427,231	76,049,665
Net loss per share – basic and diluted (in dollars per share)	$ (0.09)	$ (0.15)

Note 14 - Net Loss Per Share _2

Note 14 - Net Loss Per Share - Antidilutive Securities Excluded from Computation (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive securities (in shares)	136,510,399	29,819,656
Convertible Notes Payable [Member]
Antidilutive securities (in shares)	1,732,703	1,732,703
Common Stock Warrants [Member]
Antidilutive securities (in shares)	105,432,083	4,477,045
Share-Based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	21,985,334	16,205,404
Restricted Stock [Member]
Antidilutive securities (in shares)	767,945	812,170
Contingent Earnout Shares [Member]
Antidilutive securities (in shares)	6,592,334	6,592,334

Note 15 - Related Party Trans_3

Note 15 - Related Party Transactions (Details Textual)	1 Months Ended	3 Months Ended
	Aug. 31, 2018	Mar. 31, 2024
Related Party Transaction, Royalty Fee Rate for Revenues	3%
Supply Agreement [Member] | 4Life [Member]
Related Party Transaction, Rate	20%
License Agreement [Member] | 4Life [Member]
Related Party Transaction, Exclusive Supply Term (Year)		5 years

Note 15 - Related Party Trans_4

Note 15 - Related Party Transactions - Revenue From 4Life Agreement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue	$ 73	$ 107
Related Party [Member]
Revenue	72	106
Product [Member]
Revenue	44	64
Product [Member] | Related Party [Member]
Revenue	43	63
Royalty [Member]
Revenue	29	43
Royalty [Member] | Related Party [Member]
Revenue	$ 29	$ 43

Note 16 - Subsequent Events (De

Note 16 - Subsequent Events (Details Textual) - Subsequent Event [Member] - USD ($) $ in Millions	7 Months Ended
	May 08, 2024	Apr. 09, 2024
NIH Grant Awarded to Clene, Columbia University, and Synapticure [Member]
Government Assistance, Award Amount		$ 45.1
NIH Grant Subawards [Member]
Government Assistance, Award Amount		30.9
NIH Grant Subaward One [Member]
Government Assistance, Award Amount		$ 7.3
NIH Grant [Member]
Research and Development Arrangement with Federal Government, Costs Incurred, Net	$ 3.1