Panbela Therapeutics (PBLA) 10-K 24 Mar 20 2019 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 20, 2020	Jun. 30, 2019
Document Information [Line Items]
Entity Registrant Name	Sun BioPharma, Inc.
Entity Central Index Key	0001029125
Trading Symbol	snbp
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding (in shares)		6,631,308
Entity Public Float			$ 9,495,538
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Title of 12(g) Security	Common Stock, $0.001 par value

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 2,449,000	$ 1,405,000
Prepaid expenses and other current assets	283,000	110,000
Income tax receivable	361,000	332,000
Total current assets	3,093,000	1,847,000
Other noncurrent assets	51,000	51,000
Total assets	3,144,000	1,898,000
Current liabilities:
Accounts payable	597,000	1,064,000
Accrued expenses	304,000	216,000
Convertible notes payable, net of debt discounts		64,000
Term debt, current portion	116,000	286,000
Unsecured promissory note payable	742,000
Total current liabilities	1,759,000	1,630,000
Total liabilities	1,759,000	1,630,000
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 authorized; no shares issued or outstanding as of December 31, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value; 100,000,000 authorized; 6,631,308 and 5,077,483 shares issued and outstanding, as of December 31, 2019 and December 31, 2018, respectively	7,000	5,000
Additional paid-in capital	42,331,000	35,038,000
Accumulated deficit	(41,258,000)	(35,058,000)
Accumulated comprehensive income	305,000	283,000
Total stockholders' equity	1,385,000	268,000
Total liabilities and stockholders' equity	$ 3,144,000	$ 1,898,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	6,631,308	5,077,483
Common stock, shares outstanding (in shares)	6,631,308	5,077,483

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
General and administrative	$ 1,973	$ 2,108
Research and development	2,349	1,783
Operating loss	(4,322)	(3,891)
Other (expense) income:
Grant income		54
Interest expense	(2,194)	(1,814)
Other expense	(99)	(508)
Total other expense	(2,293)	(2,268)
Loss before income tax benefit	(6,615)	(6,159)
Income tax benefit	415	254
Net loss	(6,200)	(5,905)
Foreign currency translation adjustment	22	448
Comprehensive loss	$ (6,178)	$ (5,457)
Basic and diluted net loss per share (in dollars per share)	$ (1.09)	$ (1.27)
Weighted average shares outstanding - basic and diluted (in shares)	5,700,314	4,662,080

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ 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, 2017	3,842
Balances at Dec. 31, 2017	$ 4	$ 25,625	$ (29,153)	$ (165)	$ (3,689)
Sale of common stock and warrants (in shares)	485
Sale of common stock and warrants		2,328			2,328
Beneficial conversion feature		716			716
Conversion of convertible notes payable and accrued interest into common stock and warrants (in shares)	751
Conversion of convertible notes payable and accrued interest into common stock and warrants	$ 1	3,257			3,258
Warrants issued with sale of convertible notes payable		739			739
Stock-based compensation		2,373			2,373
Net loss			(5,905)		(5,905)
Foreign currency translation adjustment				448	448
Common stock converted into convertible notes payable
Balances (in shares) at Dec. 31, 2018	5,078
Balances at Dec. 31, 2018	$ 5	35,038	(35,058)	283	268
Sale of common stock and warrants (in shares)	909
Sale of common stock and warrants	$ 1	3,159			3,160
Beneficial conversion feature		353			353
Warrants issued with sale of convertible notes payable		419			419
Stock-based compensation		1,093			1,093
Net loss			(6,200)		(6,200)
Foreign currency translation adjustment				22	22
Conversion of convertible notes payable and accrued interest into common stock (in shares)	651
Conversion of convertible notes payable and accrued interest into common stock	$ 1	2,280			2,281
Common stock converted into convertible notes payable (in shares)	(7)
Common stock converted into convertible notes payable		(25)			(25)
Warrants issued in exchange for modification of term debt		14			14
Balances (in shares) at Dec. 31, 2019	6,631
Balances at Dec. 31, 2019	$ 7	$ 42,331	$ (41,258)	$ 305	$ 1,385

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (6,200)	$ (5,905)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,093	1,279
Amortization of debt discount	2,066	1,732
Amortization of debt issuance costs	12	9
Non-cash interest expense	102	4
Changes in operating assets and liabilities:
Income tax receivable	(31)	50
Prepaid expenses and other current assets	(174)	25
Accounts payable	301	360
Accrued liabilities	92	59
Net cash used in operating activities	(2,739)	(2,387)
Cash flows from financing activities:
Proceeds from the sale of convertible promissory notes and warrants, net of debt issuance costs of $7 and $5 respectively	810	1,329
Proceeds from sale of common stock and warrants, net of offering costs of $16 and $27 respectively	3,160	2,328
Repayment of demand note	(25)
Repayments of term debt	(161)	(14)
Net cash provided by financing activities	3,784	3,643
Effect of exchange rate changes on cash	(1)	(3)
Net change in cash	1,044	1,253
Cash at beginning of period	1,405	152
Cash at end of period	2,449	1,405
Supplemental disclosure of cash flow information:
Cash paid during period for interest	14	67
Supplemental disclosure of non-cash transactions:
Beneficial conversion feature on convertible notes	353	716
Warrants issued with convertible notes	419	739
Warrants issued in exchange for modification of term debt	14
Common stock converted into convertible notes payable	(25)
Conversion of convertible notes payable and accrued interest into common stock and warrants		3,258
Conversion of convertible notes payable and accrued interest into common stock	2,281
Issuance of unsecured promissory note in exchange for vendor accounts payable	742
Options granted in exchange for release from contingent payment obligations		$ 1,094

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Proceeds from the sale of convertible promissory notes, offering costs	$ 7	$ 5
Proceeds from issuance of common stock and warrants, issuance costs	$ 16	$ 27

Note 1 - Business

Note 1 - Business	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. Business Sun BioPharma, Inc. and its wholly owned subsidiary Sun BioPharma Australia Pty Ltd. (collectively “we,” “us,” “our,” and the “Company”) exist for the primary purpose of advancing the commercial development of a proprietary polyamine analogue for pancreatic cancer. We have exclusively licensed the worldwide rights to this compound, which has been designated as SBP- 101, September 21, 2011. May 24, 2013

Note 2 - Risks and Uncertaintie

Note 2 - Risks and Uncertainties	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Nature of Operations [Text Block]	2. Risks and Uncertainties The Company operates in a highly regulated and competitive environment. The development, manufacturing and marketing of pharmaceutical products require approval from, and are subject to ongoing oversight by, the Food and Drug Administration (“FDA”) in the United States, the Therapeutic Goods Administration (“TGA”) in Australia, the European Medicines Agency (“EMA”) in the European Union, and comparable agencies in other countries. Obtaining approval for a new pharmaceutical product is never certain, may We have incurred losses of $41.3 2011. December 31, 2019 $6.2 $2.7 101. December 31, 2019, $2.4 $1.3 $1.4 The accompanying Consolidated Financial Statements have been prepared assuming that we will continue as a going concern which contemplates the realization of assets and liquidation of liabilities in the normal course of business and do not 101,

Note 3 - Liquidity and Business

Note 3 - Liquidity and Business Plan	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Substantial Doubt about Going Concern [Text Block]	3. Liquidity and Management Plans We will need to seek additional sources of funds to support our current business plans. We may no not If we are unable to obtain additional financing when needed, we would need to scale back our operations taking actions that may 101 third 101 In closings occurring in August, September October 2019 909,209 $3.2 five $4.00. In closings occurring in December 2018 January 2019 $2.2 1,243,498 June 30, 2019 $105,000 651,758 $3.50. 6 five $4.50. Our future success is dependent upon our ability to obtain additional financing, the success of our development efforts, our ability to demonstrate clinical progress for our SBP- 101 101 not not There can be no

Note 4 - Summary of Significant

Note 4 - Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Significant Accounting Policies [Text Block]	4. Summary of Significant Accounting Policies Basis of p resentation We have prepared the accompanying Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Our fiscal year ends on December 31. Principles of consolidation The accompanying Consolidated Financial Statements include the assets, liabilities and expenses of Sun BioPharma, Inc. and our wholly owned subsidiary. All significant intercompany transactions and balances have been eliminated in consolidation. Use of estimates The preparation of Consolidated Financial Statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimates. Concentration of c redit r isk Financial instruments that potentially subject the company to significant concentrations of credit risk consist primarily of cash. Cash is deposited in demand accounts at commercial banks. At times, such deposits may not Beneficial conversion feature For convertible debt where the rate of conversion is below fair market value for our common stock, the Company records a charge for the beneficial conversion feature (“BCF”) and related debt discount which is presented as a direct deduction from the carrying amount of the related debt. The discount is amortized to interest expense over the life of the debt. Debt issuance costs Costs associated with the issuance of debt instruments are presented as a direct deduction from the carrying amount of the related debt. These costs are amortized on a straight-line basis, which approximates the effective interest method, over the term of the debt agreements and are included in interest expense. Research and development costs Research and development costs include expenses incurred in the conduct of our Phase 1 third 101 101 We charge research and development costs, including clinical trial costs, to expense when incurred. Our human clinical trials are performed at clinical trial sites and are administered jointly by us with assistance from contract research organizations (“CROs”). Costs of setting up clinical trial sites are accrued upon execution of the study agreement. Expenses related to the performance of clinical trials generally are accrued based on contracted amounts and the achievement of agreed upon milestones, such as patient enrollment, patient follow-up, etc. We monitor levels of performance under each significant contract, including the extent of patient enrollment and other activities through communications with the clinical trial sites and CROs, and adjust the estimates, if required, on a quarterly basis so that clinical expenses reflect the actual effort expended at each clinical trial site and by each CRO. We expense costs associated with obtaining licenses for patented technologies when it is determined there is no S tock -based compensation In accounting for stock-based incentive awards we measure and recognize the cost of employee and non-employee services received in exchange for awards of equity instruments based on the grant date fair value of those awards. Compensation cost is recognized ratably using the straight-line attribution method over the vesting period, which is considered to be the requisite service period. We record forfeitures in the periods in which they occur. The compensation expense for performance-based stock option awards is recognized when “performance” has occurred or is probable of occurring. The fair value of stock-based awards is estimated at the date of grant using the Black-Scholes option pricing model. The determination of the fair value of stock-based awards is affected by our stock price, as well as assumptions regarding a number of complex and subjective variables. Risk free interest rates are based upon U.S. Treasury rates appropriate for the expected term of each award. Expected volatility rates are based primarily on the volatility rates of a set of guideline companies, which consist of public and recently public biotechnology companies. The assumed dividend yield is zero not Income taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the Consolidated Financial Statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted rates, for each of the jurisdictions in which the Company operates, expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. Valuation allowances are established when necessary to reduce deferred tax assets to the amount that is more likely than not December 31, 2019 2018. Foreign c urrency t ranslation The functional currency of Sun BioPharma Australia Pty Ltd is the Australian Dollar (“AUD”). Accordingly, assets and liabilities, and equity transactions of Sun BioPharma Australia Pty Ltd are translated into U.S. dollars at period-end exchange rates. Expenses are translated at the average exchange rate in effect for the period. The resulting translation gains and losses are recorded as a component of accumulated comprehensive gain (loss) in the Consolidated Statements of Operations and Comprehensive Loss. During the years ended December 31, 2019 2018, Grant Income Grant income is derived from a one $225,000 101 December 31, 2018 Comprehensive l oss Comprehensive loss consists of our net loss and the effects of foreign currency translation. Net l oss per s hare We compute net loss per share by dividing our net loss (the numerator) by the weighted-average number of common shares outstanding (the denominator) during the period. Shares issued during the period and shares reacquired during the period, if any, are weighted for the portion of the period that they were outstanding. The computation of diluted earnings per share, or EPS, is similar to the computation of basic EPS except that the denominator is increased to include the number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued. Our diluted EPS is the same as basic EPS due to common equivalent shares being excluded from the calculation, as their effect is anti-dilutive. The following outstanding potential common shares were not not December 31, 2019 2018 Employee and non-employee stock options 1,744,811 1,032,211 Estimated common shares issuable upon conversion of notes payable and accrued interest - 383,947 Common stock issuable under common stock purchase warrants 3,422,099 2,035,197 5,166,910 3,451,355 Recently Adopted Accounting Pronouncement s In June 2018, 2018 07, 718 2018 07 January 1, 2019. In February 2016, 2016 02, 842 12 not January 1, 2019. no no one

Note 5 - Accrued Expenses

Note 5 - Accrued Expenses	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Accrued Liabilities [Text Block]	5 . Accrued Expenses Accrued expenses consisted of the following (in thousands): December 31, 2019 2018 Clinical trial and related expenses $ 147 $ 42 Professional services 125 157 Other 32 17 Total accrued liabilities $ 304 $ 216

Note 6 - Indebtedness

Note 6 - Indebtedness	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Debt Disclosure [Text Block]	6. Indebtedness 2018 Convertible notes payable In December 2018 January 2019, “2018 $2.2 2018 June 30, 2019 10.0% 2018 1 June 30, 2019 2 $6.0 $3.50 2018 two $3.50 2018 1,243,498 December January $4.50 5 $2.5 2018 $0.9 2018 June 30, 2019, $2.2 $105,000 $3.50 651,758 2017 Convertible notes payable In 2017 “2017 $3.1 2017 December 1, 2018 5.0% 2017 2017 $2.0 2017 2017 $10.10 2017 $3.0 2017 2017 On May 16, 2018, $2.0 2017 $3.1 $183,000 104,463 646,279 one 2018 3 9 no $121,000 $1.0 The following table sets forth the changes in convertible notes payable during the year ended December 31, 2019 ( Convertible Notes Payable Principal Accrued Interest Balances at January 1, 2019 $ 1,359 $ 2 Aggregate principal value of notes sold 816 - Accrued Interest on notes - 103 Aggregate principal value of notes and accrued interest converted into common stock (2,175 ) (105 ) - - Balances at December 31, 2019 $ - $ - Term debt On October 26, 2012, $300,000 4.125%. No October 26, 2017, October 26, 2017, May 1, 2019 $10,000 May 1, 2018 May 1, 2019. April 5, 2019 May 1, 2019 December 31, 2019. 5,555 $4.50. five December 16, 2019 $50,000 December 31, 2019 5,000 $4.00 December 31, 2019 December 31, 2020. $14,000 $10,000 first December 31, 2019 $116,000.

Note 7 - Commitments and Contin

Note 7 - Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	7 . Commitments and Contingencies License agreement On December 22, 2011, first December 12, 2016 ( October 3, 2019 ( 2.5% 5% 1 ten first 2 The amended license agreement remains subject to customary and usual termination provisions. The Company must also pay an annual license maintenance fee of $10,000. $10,000 2019 2018

Note 8 - Stockholders' Equity (

Note 8 - Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Stockholders' Equity Note Disclosure [Text Block]	8 . Stockholder s’ Equity ( Deficit ) 2019 On closings occurring in August, September October 2019, 909,209 2019 $3.2 $240,000 2019 five $4.00 4, 201 8 Private placement On February 20, 2018, “2018 two March May 2018, 468,200 2018 three $5.00 $2.3 2018 $125,000 December 31, 2019, 468,200 Shares r eserved Shares of common stock reserved for future issuance were as follows as of December 31, 2019: Stock options outstanding 1,744,811 Shares available for grant under equity incentive plan 19,549 Common shares issuable under outstanding common stock purchase warrants 3,422,099 5,186,459

Note 9 - Stock-based Compensati

Note 9 - Stock-based Compensation	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	9 . Stock- B ased Compensation 2016 Stock-based awards are granted under the Sun BioPharma, Inc. 2016 “2016 2016 2016 no 2016 ten 1,500,000 2016 December 31, 2019, 1,480,451 2016 2011 Prior to approval of the 2016 2011 “2011 2016 2011 2011 2011 ten zero two December 31, 2019, 264,360 2011 We recognize stock-based compensation based on the fair value of each award as estimated using the Black-Scholes option valuation model. Ultimately, the actual expense recognized over the vesting period will only be for those shares that actually vest. A summary of option activity is as follows: Shares Available for Grant Shares Underlying Options Weighted Average Exercise Price Per Share Aggregate Intrinsic Value Balance at January 1, 2018 1,060,400 733,960 $ 9.79 $ 169,495 Granted (404,000 ) 404,000 7.49 Exercised - (30,000 ) 2.20 Cancelled - - - Forfeitures 75,749 (75,749 ) 7.34 Balance at December 31, 2018 732,149 1,032,211 $ 8.90 $ 56,225 Granted (733,400 ) 733,400 3.42 Exercised - - - Cancelled - - - Forfeitures 20,800 (20,800 ) 15.10 Balance at December 31, 2019 19,549 1,744,811 $ 6.53 $ 1,030,547 A summary of the status of our unvested shares during the year ended and as of December 31, 2019 Shares Under Option Weighted Average Grant Date Fair Value Unvested at December 31, 2018 42,500 $ 4.83 Granted 733,400 2.09 Vested (378,025 ) 2.41 Forefeitures - - Unvested at December 31, 2019 397,875 $ 2.03 Information about stock options outstanding, vested and expected to vest as of December 31, 2019, Outstanding, Vested and Expected to Vest Options Vested and Excercisable Per Share Exercise Price Shares Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Options Excercisable Weighted Average Remaining Contractual Life (Years) $0.875 - $1.10 26,360 3.00 $ 1.029 26,360 3.00 $2.275 - $2.50 38,000 4.12 $ 2.464 38,000 4.12 $2.95 - $3.70 774,100 8.32 $ 3.040 411,525 7.36 $4.50 - $8.10 538,300 7.97 $ 6.742 506,500 7.92 $10.00 - $10.10 54,000 7.55 $ 10.007 54,000 7.55 $15.10 314,051 6.41 $ 15.100 310,551 6.46 Totals 1,744,811 7.67 $ 6.526 1,346,936 7.19 As of December 31, 2019, not $372,000 2.4 The assumptions used in calculating the fair value under the Black-Scholes option valuation model are set forth in the following table for options issued by the Company for the years ended December 31, 2019 2018: 2019 2018 Common stock fair value $2.95 - $5.00 $3.50 - $8.10 Risk-free interest rate 1.55% - 2.25% 2.30% - 2.94% Expected dividend yield 0 0 Expected Option life (in years) 5.00 - 5.50 1.25 - 5.75 Expected stock price volatility 72% 72% Nonemployee s tock- b ased c ompensation We account for stock options granted to nonemployees in accordance with Accounting Standards Update (“ASU”) 2018 07, 718 $288,000 $263,000 December 31, 2019 2018,

Note 10 - Income Taxes

Note 10 - Income Taxes	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Income Tax Disclosure [Text Block]	10 . Income Taxes We have incurred net operating losses since inception. We have not At December 31, 2019 2018, $361,000 $332,000, Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes as well as operating losses and tax credit carryforwards. The significant components of our deferred tax assets and liabilities are as follows (in thousands): December 31, Deferred tax assets (liabilities) 2019 2018 Net operating loss carryforwards $ 6,307 $ 4,807 Research credit carryforwards 235 235 Stock-based compensation 1,230 971 Other 72 71 Deferred tax assets 7,844 6,084 Valuation allowance (7,844 ) (5,801 ) Deferred tax assets, net of valuation allowance - 283 Beneficial conversion feature, net - (283 ) Deferrred tax liabilities - (283 ) Net deferred tax asset $ - $ - Realization of the future tax benefits is dependent on our ability to generate sufficient taxable income within the carry-forward period. Because of our history of operating losses, management believes that the deferred tax assets arising from the above-mentioned future tax benefits are currently not A reconciliation of the statutory tax rates and the effective tax rates is as follows: Year Ended December 31, 2019 2018 Statutory rate 21.0 % 21.0 % Permanent differences (5.9 ) 0.1 Change in effective tax rate - 0.6 Valuation allowance (32.4 ) (22.6 ) Foreign research incentives 5.7 5.7 Deferred true-up 16.3 - Other 1.0 0.9 Effective rate 5.7 % 5.7 % Net operating losses and tax credit carryforwards as of December 31, 2019, Amount (in thousands) Expiration Years Net operating losses--federal 12,958 Expires beginning 2031 2019 net operating loss -- federal 3,153 Never expires Tax credits--federal 235 Beginning 2041 Utilization of the net operating loss carryforwards and credits may not 382 The Company is subject to taxation in the United States and Australia. Tax returns for the year ended December 31, 2015 December 31, 2014

Note 11 - Subsequent Events

Note 11 - Subsequent Events	12 Months Ended
	Dec. 31, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	11 . Subsequent Event s On February 21, 2020 75,000 5 $148,000

Significant Accounting Policies

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of p resentation We have prepared the accompanying Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Our fiscal year ends on December 31.
Consolidation, Policy [Policy Text Block]	Principles of consolidation The accompanying Consolidated Financial Statements include the assets, liabilities and expenses of Sun BioPharma, Inc. and our wholly owned subsidiary. All significant intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates, Policy [Policy Text Block]	Use of estimates The preparation of Consolidated Financial Statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Concentration of c redit r isk Financial instruments that potentially subject the company to significant concentrations of credit risk consist primarily of cash. Cash is deposited in demand accounts at commercial banks. At times, such deposits may not
Beneficial Conversion Feature, Policy [Policy Text Block]	Beneficial conversion feature For convertible debt where the rate of conversion is below fair market value for our common stock, the Company records a charge for the beneficial conversion feature (“BCF”) and related debt discount which is presented as a direct deduction from the carrying amount of the related debt. The discount is amortized to interest expense over the life of the debt.
Debt Issuance Costs [Policy Text Block]	Debt issuance costs Costs associated with the issuance of debt instruments are presented as a direct deduction from the carrying amount of the related debt. These costs are amortized on a straight-line basis, which approximates the effective interest method, over the term of the debt agreements and are included in interest expense.
Research and Development Expense, Policy [Policy Text Block]	Research and development costs Research and development costs include expenses incurred in the conduct of our Phase 1 third 101 101 We charge research and development costs, including clinical trial costs, to expense when incurred. Our human clinical trials are performed at clinical trial sites and are administered jointly by us with assistance from contract research organizations (“CROs”). Costs of setting up clinical trial sites are accrued upon execution of the study agreement. Expenses related to the performance of clinical trials generally are accrued based on contracted amounts and the achievement of agreed upon milestones, such as patient enrollment, patient follow-up, etc. We monitor levels of performance under each significant contract, including the extent of patient enrollment and other activities through communications with the clinical trial sites and CROs, and adjust the estimates, if required, on a quarterly basis so that clinical expenses reflect the actual effort expended at each clinical trial site and by each CRO. We expense costs associated with obtaining licenses for patented technologies when it is determined there is no
Share-based Payment Arrangement [Policy Text Block]	S tock -based compensation In accounting for stock-based incentive awards we measure and recognize the cost of employee and non-employee services received in exchange for awards of equity instruments based on the grant date fair value of those awards. Compensation cost is recognized ratably using the straight-line attribution method over the vesting period, which is considered to be the requisite service period. We record forfeitures in the periods in which they occur. The compensation expense for performance-based stock option awards is recognized when “performance” has occurred or is probable of occurring. The fair value of stock-based awards is estimated at the date of grant using the Black-Scholes option pricing model. The determination of the fair value of stock-based awards is affected by our stock price, as well as assumptions regarding a number of complex and subjective variables. Risk free interest rates are based upon U.S. Treasury rates appropriate for the expected term of each award. Expected volatility rates are based primarily on the volatility rates of a set of guideline companies, which consist of public and recently public biotechnology companies. The assumed dividend yield is zero not
Income Tax, Policy [Policy Text Block]	Income taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the Consolidated Financial Statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted rates, for each of the jurisdictions in which the Company operates, expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. Valuation allowances are established when necessary to reduce deferred tax assets to the amount that is more likely than not December 31, 2019 2018.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign c urrency t ranslation The functional currency of Sun BioPharma Australia Pty Ltd is the Australian Dollar (“AUD”). Accordingly, assets and liabilities, and equity transactions of Sun BioPharma Australia Pty Ltd are translated into U.S. dollars at period-end exchange rates. Expenses are translated at the average exchange rate in effect for the period. The resulting translation gains and losses are recorded as a component of accumulated comprehensive gain (loss) in the Consolidated Statements of Operations and Comprehensive Loss. During the years ended December 31, 2019 2018,
Grant Income Policy [Policy Text Block]	Grant Income Grant income is derived from a one $225,000 101 December 31, 2018
Comprehensive Income, Policy [Policy Text Block]	Comprehensive l oss Comprehensive loss consists of our net loss and the effects of foreign currency translation.
Earnings Per Share, Policy [Policy Text Block]	Net l oss per s hare We compute net loss per share by dividing our net loss (the numerator) by the weighted-average number of common shares outstanding (the denominator) during the period. Shares issued during the period and shares reacquired during the period, if any, are weighted for the portion of the period that they were outstanding. The computation of diluted earnings per share, or EPS, is similar to the computation of basic EPS except that the denominator is increased to include the number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued. Our diluted EPS is the same as basic EPS due to common equivalent shares being excluded from the calculation, as their effect is anti-dilutive. The following outstanding potential common shares were not not December 31, 2019 2018 Employee and non-employee stock options 1,744,811 1,032,211 Estimated common shares issuable upon conversion of notes payable and accrued interest - 383,947 Common stock issuable under common stock purchase warrants 3,422,099 2,035,197 5,166,910 3,451,355
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Adopted Accounting Pronouncement s In June 2018, 2018 07, 718 2018 07 January 1, 2019. In February 2016, 2016 02, 842 12 not January 1, 2019. no no one

Note 4 - Summary of Significa_2

Note 4 - Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	December 31, 2019 2018 Employee and non-employee stock options 1,744,811 1,032,211 Estimated common shares issuable upon conversion of notes payable and accrued interest - 383,947 Common stock issuable under common stock purchase warrants 3,422,099 2,035,197 5,166,910 3,451,355

Note 5 - Accrued Expenses (Tabl

Note 5 - Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Schedule of Accrued Liabilities [Table Text Block]	December 31, 2019 2018 Clinical trial and related expenses $ 147 $ 42 Professional services 125 157 Other 32 17 Total accrued liabilities $ 304 $ 216

Note 6 - Indebtedness (Tables)

Note 6 - Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Schedule of Debt Activity [Table Text Block]	Convertible Notes Payable Principal Accrued Interest Balances at January 1, 2019 $ 1,359 $ 2 Aggregate principal value of notes sold 816 - Accrued Interest on notes - 103 Aggregate principal value of notes and accrued interest converted into common stock (2,175 ) (105 ) - - Balances at December 31, 2019 $ - $ -

Note 8 - Stockholders' Equity_2

Note 8 - Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Schedule of Common Stock Reserved for Future Issuance [Table Text Block]	Stock options outstanding 1,744,811 Shares available for grant under equity incentive plan 19,549 Common shares issuable under outstanding common stock purchase warrants 3,422,099 5,186,459

Note 9 - Stock-based Compensa_2

Note 9 - Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Shares Available for Grant Shares Underlying Options Weighted Average Exercise Price Per Share Aggregate Intrinsic Value Balance at January 1, 2018 1,060,400 733,960 $ 9.79 $ 169,495 Granted (404,000 ) 404,000 7.49 Exercised - (30,000 ) 2.20 Cancelled - - - Forfeitures 75,749 (75,749 ) 7.34 Balance at December 31, 2018 732,149 1,032,211 $ 8.90 $ 56,225 Granted (733,400 ) 733,400 3.42 Exercised - - - Cancelled - - - Forfeitures 20,800 (20,800 ) 15.10 Balance at December 31, 2019 19,549 1,744,811 $ 6.53 $ 1,030,547
Schedule of Nonvested Share Activity [Table Text Block]	Shares Under Option Weighted Average Grant Date Fair Value Unvested at December 31, 2018 42,500 $ 4.83 Granted 733,400 2.09 Vested (378,025 ) 2.41 Forefeitures - - Unvested at December 31, 2019 397,875 $ 2.03
Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]	Outstanding, Vested and Expected to Vest Options Vested and Excercisable Per Share Exercise Price Shares Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Options Excercisable Weighted Average Remaining Contractual Life (Years) $0.875 - $1.10 26,360 3.00 $ 1.029 26,360 3.00 $2.275 - $2.50 38,000 4.12 $ 2.464 38,000 4.12 $2.95 - $3.70 774,100 8.32 $ 3.040 411,525 7.36 $4.50 - $8.10 538,300 7.97 $ 6.742 506,500 7.92 $10.00 - $10.10 54,000 7.55 $ 10.007 54,000 7.55 $15.10 314,051 6.41 $ 15.100 310,551 6.46 Totals 1,744,811 7.67 $ 6.526 1,346,936 7.19
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	2019 2018 Common stock fair value $2.95 - $5.00 $3.50 - $8.10 Risk-free interest rate 1.55% - 2.25% 2.30% - 2.94% Expected dividend yield 0 0 Expected Option life (in years) 5.00 - 5.50 1.25 - 5.75 Expected stock price volatility 72% 72%

Note 10 - Income Taxes (Tables)

Note 10 - Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Tables
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	December 31, Deferred tax assets (liabilities) 2019 2018 Net operating loss carryforwards $ 6,307 $ 4,807 Research credit carryforwards 235 235 Stock-based compensation 1,230 971 Other 72 71 Deferred tax assets 7,844 6,084 Valuation allowance (7,844 ) (5,801 ) Deferred tax assets, net of valuation allowance - 283 Beneficial conversion feature, net - (283 ) Deferrred tax liabilities - (283 ) Net deferred tax asset $ - $ -
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2019 2018 Statutory rate 21.0 % 21.0 % Permanent differences (5.9 ) 0.1 Change in effective tax rate - 0.6 Valuation allowance (32.4 ) (22.6 ) Foreign research incentives 5.7 5.7 Deferred true-up 16.3 - Other 1.0 0.9 Effective rate 5.7 % 5.7 %
Summary of Operating Loss and Tax Credit Carryforwards [Table Text Block]	Amount (in thousands) Expiration Years Net operating losses--federal 12,958 Expires beginning 2031 2019 net operating loss -- federal 3,153 Never expires Tax credits--federal 235 Beginning 2041

Note 2 - Risks and Uncertaint_2

Note 2 - Risks and Uncertainties (Details Textual) - USD ($) $ in Thousands	12 Months Ended		108 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Net Income (Loss) Attributable to Parent, Total	$ (6,200)	$ (5,905)	$ (41,300)
Net Cash Provided by (Used in) Operating Activities, Total	(2,739)	(2,387)
Cash and Cash Equivalents, at Carrying Value, Ending Balance	2,449	1,405	2,449	$ 152
Working Capital	1,300		1,300
Stockholders' Equity Attributable to Parent, Ending Balance	$ 1,385	$ 268	$ 1,385	$ (3,689)

Note 3 - Liquidity and Busine_2

Note 3 - Liquidity and Business Plan (Details Textual) - USD ($)	Jun. 30, 2019	Jan. 31, 2019	Oct. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Proceeds from Issuance of Private Placement				$ 3,160,000	$ 2,328,000
Proceeds from Convertible Debt				$ 810,000	$ 1,329,000
Conversion from Debt Notes to Common Stock [Member]
Debt Conversion, Accrued Interest, Amount	$ 105,000
Debt Conversion, Converted Instrument, Shares Issued	651,758
Debt Instrument, Convertible, Conversion Price	$ 3.50
Unsecured Convertible Promissory Notes [Member]
Proceeds from Convertible Debt		$ 2,200,000
Warrants in Connection with the Private Placement [Member]
Warrants and Rights Outstanding, Term			5 years
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			909,209
Warrants In Connection with 2018 Convertible Notes Payable [Member]
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 4.50
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		1,243,498
Warrants in Connection with Securities Purchase Agreement [Member]
Warrants and Rights Outstanding, Term	5 years
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.50		$ 4		$ 5
Private Placement [Member]
Stock Issued During Period, Shares, New Issues			909,209		468,200
Proceeds from Issuance of Private Placement			$ 3,200,000		$ 2,300,000

Note 4 - Summary of Significa_3

Note 4 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%
Grant Agreement, Total Grants		$ 225,000

Note 4 - Summary of Significa_4

Note 4 - Summary of Significant Accounting Policies - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Anti-dilutive securities (in shares)	5,166,910	3,451,355
Share-based Payment Arrangement [Member]
Anti-dilutive securities (in shares)	1,744,811	1,032,211
Convertible Debt Securities [Member]
Anti-dilutive securities (in shares)		383,947
Warrant [Member]
Anti-dilutive securities (in shares)	3,422,099	2,035,197

Note 5 - Accrued Expenses - Acc

Note 5 - Accrued Expenses - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Clinical trial and related expenses	$ 147	$ 42
Professional services	125	157
Other	32	17
Accrued liabilities	$ 304	$ 216

Note 6 - Indebtedness (Details

Note 6 - Indebtedness (Details Textual) - USD ($)	Dec. 16, 2019	Jun. 30, 2019	Apr. 05, 2019	May 16, 2018	May 01, 2018	Mar. 17, 2017	Jan. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Oct. 26, 2012
Proceeds from Convertible Debt								$ 810,000	$ 1,329,000
Intrinsic Value of Convertible Debt with Conversion Feature								353,000	716,000
Debt Instrument, Convertible, Gross Proceeds from Sale of Equity Trigger				$ 2,000,000
Repayments of Long-term Debt, Total								161,000	$ 14,000
Institute [Member]
Debt Instrument, Interest Rate, Stated Percentage										4.125%
Debt Instrument, Face Amount										$ 300,000
Conversion from Debt to Common Stock [Member]
Debt Instrument, Convertible, Conversion Price		$ 3.50
Debt Conversion, Original Debt, Amount		$ 2,200,000		3,100,000
Debt Conversion, Accrued Interest, Amount		$ 105,000		$ 183,000
Debt Conversion, Converted Instrument, Shares Issued		651,758		104,463
Debt Conversion, Converted Instrument, Units Issued				646,279
Debt Instrument, Unamortized Discount, Total				$ 121,000
Warrants In Connection with 2018 Convertible Notes Payable [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							2
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,243,498
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 4.50
Warrants and Rights Outstanding, Term							5 years
Warrants Upon Issuance, Fair Value							$ 2,500,000
Warrants in Connection with Debt Conversion [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				1
Warrants In Connection with Term Debt [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			5,555
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4.50
Warrants and Rights Outstanding, Term			5 years
Warrants Issued in Connection with Second Amended Unsecured Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	5,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4
Warrants Issued for Both Amendments to the Unsecured Loan Agreement [Member]
Warrants and Rights Outstanding	$ 14,000
Convertible Debt [Member]
Proceeds from Convertible Debt								816,000
Debt Conversion, Original Debt, Amount								2,175,000
The 2018 Notes [Member]
Proceeds from Convertible Debt							2,200,000
Convertible Debt, Mandatory Conversion Threshold, Gross Proceeds from Sale of Equity Securities							6,000,000
Class of Warrant or Right, Principal Amount of Every Amount Of Notes Purchased							3.50
Intrinsic Value of Convertible Debt with Conversion Feature							$ 900,000
The 2018 Notes [Member] | Convertible Debt [Member]
Debt Instrument, Interest Rate, Stated Percentage							10.00%
Debt Instrument, Convertible, Conversion Price							$ 3.50
The 2017 Notes [Member]
Proceeds from Convertible Debt, Gross						$ 3,100,000
Unamortized Debt Discount Charged to Interest Expense				$ 1,000,000
The 2017 Notes [Member] | Convertible Debt [Member]
Debt Instrument, Interest Rate, Stated Percentage						5.00%
Debt Instrument, Convertible, Conversion Price						$ 10.10
Debt Instrument, Qualified Financing, Minimum Proceeds						$ 2,000,000
Debt Instrument, Convertible, Beneficial Conversion Feature						$ 3,000,000
Amended Unsecured Loan Agreement [Member] | Institute [Member]
Debt Instrument, Periodic Payment, Total					$ 10,000
Second Amended Unsecured Loan Agreement [Member] | Institute [Member]
Repayments of Long-term Debt, Total	$ 50,000
Term Debt [Member]
Debt Instrument, Periodic Payment, Total			$ 10,000
Long-term Debt, Total								$ 116,000

Note 6 - Indebtedness - Changes

Note 6 - Indebtedness - Changes in Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Proceeds from the sale of convertible promissory notes and warrants, net of debt issuance costs of $7 and $5 respectively	$ 810	$ 1,329
Convertible Debt [Member]
Balances at January 1, 2019	1,359
Accrued interest at January 1, 2019	2
Proceeds from the sale of convertible promissory notes and warrants, net of debt issuance costs of $7 and $5 respectively	816
Accrued Interest	103
Aggregate principal value of notes converted into common stock	(2,175)
Accrued interest converted into common stock and warrants	(105)
Balances at December 31, 2019		1,359
Accrued interest at December 31, 2019		$ 2

Note 7 - Commitments and Cont_2

Note 7 - Commitments and Contingencies (Details Textual) - Licensing Agreement with University of Florida Research Foundation [Member] - USD ($)	Dec. 22, 2011	Dec. 31, 2019	Dec. 31, 2018
Royalty Term	10 years
Annual License Maintenance Fee	$ 10,000
License Maintenance Fee [Member]
Royalty Expense		$ 10,000	$ 10,000
Minimum [Member]
Royalty Fee Percentage of Net Sales	2.50%
Maximum [Member]
Royalty Fee Percentage of Net Sales	5.00%

Note 8 - Stockholders' Equity_3

Note 8 - Stockholders' Equity (Deficit) (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
	Oct. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019
Proceeds from Issuance of Private Placement		$ 3,160,000	$ 2,328,000
Class of Warrant or Right, Outstanding		3,422,099
Warrants in Connection with Securities Purchase Agreement [Member]
Class of Warrant or Right, Expiration Term	5 years		3 years
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4		$ 5	$ 4.50
Class of Warrant or Right, Outstanding		468,200
Warrants in Connection with the Private Placement [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	909,209
Directors and Officers [Member]
Proceeds from Issuance of Private Placement	$ 240,000		$ 125,000
Private Placement [Member]
Stock Issued During Period, Shares, New Issues	909,209		468,200
Proceeds from Issuance of Private Placement	$ 3,200,000		$ 2,300,000

Note 8 - Stockholders' Deficit

Note 8 - Stockholders' Deficit - Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock options outstanding (in shares)	1,744,811
Shares available for grant under equity incentive plan (in shares)	19,549	732,149	1,060,400
Class of Warrant or Right, Outstanding	3,422,099
(in shares)	5,186,459

Note 9 - Stock-based Compensa_3

Note 9 - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Capital Shares Reserved for Future Issuance	5,186,459
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	1,744,811	1,032,211	733,960
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 372,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	2 years 146 days
Non-Employee Stock Option [Member]
Share-based Payment Arrangement, Expense	$ 288,000	$ 263,000
Sun BioPharma, Inc. 2016 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Common Stock, Capital Shares Reserved for Future Issuance	1,480,451
Sun BioPharma, Inc. 2016 Omnibus Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member]
Common Stock, Capital Shares Reserved for Future Issuance	1,500,000
Sun BioPharma, Inc. 2011 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	264,360
Sun BioPharma, Inc. 2011 Stock Option Plan [Member] | Share-based Payment Arrangement, Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	0 years
Sun BioPharma, Inc. 2011 Stock Option Plan [Member] | Share-based Payment Arrangement, Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years

Note 9 - Stock-based Compensa_4

Note 9 - Stock-based Compensation - Summary of Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance, shares available for grant (in shares)	732,149	1,060,400
Balance, shares underlying options (in shares)	1,032,211	733,960
Balance, weighted average exercise price per share (in dollars per share)	$ 6.53	$ 8.90	$ 9.79
Aggregate intrinsic value	$ 1,030,547	$ 56,225	$ 169,495
Granted, shares available for grant (in shares)	(733,400)	(404,000)
Granted, shares underlying options (in shares)	733,400	404,000
Granted, weighted average exercise price per share (in dollars per share)	$ 3.42	$ 7.49
Forfeitures , shares available for grant (in shares)	20,800	75,749
Forfeited, shares underlying options (in shares)	(20,800)	(75,749)
Forfeited, weighted average exercise price per share (in dollars per share)	$ 15.10	$ 7.34
Balance, shares available for grant (in shares)	19,549	732,149
Balance, shares underlying options (in shares)	1,744,811	1,032,211

Note 9 - Stock-based Compensa_5

Note 9 - Stock-based Compensation - Nonvested Share Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Unvested, shares under option (in shares)	42,500
Unvested, weighted average grant-date fair value (in dollars per share)	$ 4.83
Granted, shares under option (in shares)	733,400	404,000
Granted, weighted average grant-date fair value (in dollars per share)	$ 2.09
Vested, shares under option (in shares)	(378,025)
Vested, weighted average grant-date fair value (in dollars per share)	$ 2.41
Forfeitures, shares under option (in shares)
Forfeitures, weighted average grant-date fair value (in dollars per share)
Unvested, shares under option (in shares)	397,875	42,500
Unvested, weighted average grant-date fair value (in dollars per share)	$ 2.03	$ 4.83

Note 9 - Stock-based Compensa_6

Note 9 - Stock-based Compensation - Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Options outstanding (in shares) | shares	1,744,811
Options outstanding, weighted average remaining contractual life (Year)	7 years 244 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.526
Options excercisable (in shares) | shares	1,346,936
Options excercisable, weighted average remaining contractual life (Year)	7 years 69 days
Exercise Price Range 1 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 0.875
Per share exercise price, upper limit (in dollars per share)	$ 1.10
Options outstanding (in shares) | shares	26,360
Options outstanding, weighted average remaining contractual life (Year)	3 years
Options outstanding, weighted average exercise price (in dollars per share)	$ 1.029
Options excercisable (in shares) | shares	26,360
Options excercisable, weighted average remaining contractual life (Year)	3 years
Exercise Price Range 2 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 2.275
Per share exercise price, upper limit (in dollars per share)	$ 2.50
Options outstanding (in shares) | shares	38,000
Options outstanding, weighted average remaining contractual life (Year)	4 years 43 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.464
Options excercisable (in shares) | shares	38,000
Options excercisable, weighted average remaining contractual life (Year)	4 years 43 days
Exercise Price Range 3 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 2.95
Per share exercise price, upper limit (in dollars per share)	$ 3.70
Options outstanding (in shares) | shares	774,100
Options outstanding, weighted average remaining contractual life (Year)	8 years 116 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 3.04
Options excercisable (in shares) | shares	411,525
Options excercisable, weighted average remaining contractual life (Year)	7 years 131 days
Exercise Price Range 4 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 4.50
Per share exercise price, upper limit (in dollars per share)	$ 8.10
Options outstanding (in shares) | shares	538,300
Options outstanding, weighted average remaining contractual life (Year)	7 years 354 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.742
Options excercisable (in shares) | shares	506,500
Options excercisable, weighted average remaining contractual life (Year)	7 years 335 days
Exercise Price Range 5 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 10
Per share exercise price, upper limit (in dollars per share)	$ 10.10
Options outstanding (in shares) | shares	54,000
Options outstanding, weighted average remaining contractual life (Year)	7 years 200 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 10.007
Options excercisable (in shares) | shares	54,000
Options excercisable, weighted average remaining contractual life (Year)	7 years 200 days
Exercise Price Range 6 [Member]
Per share exercise price, lower limit (in dollars per share)	$ 15.10
Options outstanding (in shares) | shares	314,051
Options outstanding, weighted average remaining contractual life (Year)	6 years 149 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 15.10
Options excercisable (in shares) | shares	310,551
Options excercisable, weighted average remaining contractual life (Year)	6 years 167 days

Note 9 - Stock-based Compensa_7

Note 9 - Stock-based Compensation - Assumptions Used in Calculating Fair Value of Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Expected dividend yield	0.00%	0.00%
Expected stock price volatility	72.00%	72.00%
Minimum [Member]
Common stock fair value (in dollars per share)	$ 2.95	$ 3.50
Risk-free interest rate	1.55%	2.30%
Expected option life (Year)	5 years	1 year 91 days
Expected stock price volatility
Maximum [Member]
Common stock fair value (in dollars per share)	$ 5	$ 8.10
Risk-free interest rate	2.25%	2.94%
Expected option life (Year)	5 years 182 days	5 years 273 days
Expected stock price volatility

Note 10 - Income Taxes (Details

Note 10 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes Receivable, Current	$ 361,000	$ 332,000
Foreign Tax Authority [Member] | Australian Taxation Office [Member]
Open Tax Year	2014 2015 2016 2017 2018 2019
Domestic Tax Authority [Member]
Open Tax Year	2015 2016 2017 2018 2019
State and Local Jurisdiction [Member]
Open Tax Year	2015 2016 2017 2018 2019

Note 10 - Income Taxes - Deferr

Note 10 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Net operating loss carryforwards	$ 6,307	$ 4,807
Research credit carryforwards	235	235
Stock-based compensation	1,230	971
Other	72	71
Deferred tax assets	7,844	6,084
Valuation allowance	(7,844)	(5,801)
Deferred tax assets, net of valuation allowance		283
Beneficial conversion feature, net		(283)
Deferrred tax liabilities		(283)
Net deferred tax asset	$ 0	$ 0

Note 10 - Income Taxes - Income

Note 10 - Income Taxes - Income Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statutory rate	21.00%	21.00%
Permanent differences	(5.90%)	0.10%
Change in effective tax rate		0.60%
Valuation allowance	(32.40%)	(22.60%)
Foreign research incentives	5.70%	5.70%
Deferred true-up	16.30%
Other	1.00%	0.90%
Effective rate	5.70%	5.70%

Note 10 - Income Taxes - Net Op

Note 10 - Income Taxes - Net Operating Losses and Tax Credit Carryforwards (Details) - Domestic Tax Authority [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Net operating losses--federal	$ 12,958
Tax credits--federal	$ 235
Earliest Tax Year [Member]
Net operating losses--federal	2031
Tax credits--federal	2041
Tax Year 2018 [Member]
Net operating losses--federal	$ 3,153

Note 11 - Subsequent Events (De

Note 11 - Subsequent Events (Details Textual) - Subsequent Event [Member] - Warrants Issued as Partial Payment of Retainer Fee in Connection with Investment Banking Firm Agreement [Member]	Feb. 21, 2020USD ($)shares
Class of Warrant or Right, Issued During Period | shares	75,000
Warrants and Rights Outstanding, Term	5 years
Warrants and Rights Outstanding | $	$ 148,000