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Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2019	Mar. 12, 2020	Jun. 30, 2019
Document Information [Line Items]
Entity Registrant Name	Diffusion Pharmaceuticals Inc.
Entity Central Index Key	0001053691
Trading Symbol	dffn
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)		34,604,436
Entity Public Float			$ 13.1
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(b) Security	Common Stock, par value $0.001 per share

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 14,177,349	$ 7,991,172
Prepaid expenses, deposits and other current assets	472,464	923,059
Total current assets	14,649,813	8,914,231
Property and equipment, net	252,366	350,281
Intangible asset	8,639,000	8,639,000
Right of use asset	247,043
Other assets	322,301	298,480
Total assets	24,110,523	18,201,992
Current liabilities:
Accounts payable	1,251,412	198,818
Accrued expenses and other current liabilities	358,532	605,226
Current operating lease liability	111,477
Total current liabilities	1,721,421	804,044
Deferred income taxes	2,119,274	1,786,389
Noncurrent operating lease liability	135,566
Total liabilities	3,976,261	2,590,433
Commitments and Contingencies (Note 6)
Stockholders’ Equity:
Common stock, $0.001 par value: 1,000,000,000 shares authorized; 33,480,365 and 3,376,230 shares issued and outstanding at December 31, 2019 and 2018, respectively	33,481	3,377
Additional paid-in capital	111,824,859	95,532,881
Accumulated deficit	(91,724,078)	(79,924,699)
Total stockholders' equity	20,134,262	15,611,559
Total liabilities and stockholders' equity	$ 24,110,523	$ 18,201,992

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, issued (in shares)	33,480,365	3,376,230
Common stock, outstanding (in shares)	33,480,365	3,376,230

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 6,619,597	$ 5,751,940
General and administrative	4,834,284	6,167,177
Goodwill impairment		6,929,258
Depreciation	97,915	110,371
Loss from operations	11,551,796	18,958,746
Other expense (income):
Interest (income) expense, net	(85,302)	(151,647)
Loss from operations before income taxes	(11,466,494)	(18,807,099)
Income tax expense (benefit)	332,885	(437,289)
Net loss	(11,799,379)	(18,369,810)
Accretion of Series A cumulative preferred dividends		(85,993)
Deemed dividend related to the make-whole provision for the conversion of Series A convertible preferred stock into common stock		(8,167,895)
Net loss attributable to common stockholders	$ (11,799,379)	$ (26,623,698)
Per share information:
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (1.76)	$ (8.21)
Weighted average shares outstanding, basic and diluted (in dollars per share)	$ 6,706,509	$ 3,242,301

Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Pre-funded Warrants [Member] Common Stock [Member]	Pre-funded Warrants [Member]	Preferred Stock [Member] Series A Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2017			8,306,278	967,976
Balance at Dec. 31, 2017				$ 968	$ 82,783,865	$ (61,554,889)	$ 21,229,944
Conversion of Series A convertible preferred stock to common stock (in shares)			(8,306,278)	553,752
Conversion of Series A convertible preferred stock to common stock				$ 554	(554)
Issuance of common stock to Series A convertible preferred stockholders under make-whole adjustment feature (in shares)				777,895
Issuance of common stock to Series A convertible preferred stockholders under make-whole adjustment feature				$ 778	(778)
Issuance of common stock related to accrued dividends (in shares)				68,815
Issuance of common stock related to accrued dividends				$ 69	1,148,238		1,148,307
Series A cumulative preferred dividend					(85,993)		(85,993)
Series A cumulative preferred dividend					(85,993)		(85,993)
Issuance of common stock and warrants, net of issuance costs (in shares)				1,000,000
Issuance of common stock and warrants, net of issuance costs				$ 1,000	10,416,520		10,417,520
Common stock issued for advisory services (in shares)				7,792
Common stock issued for advisory services				$ 8	49,992		50,000
Stock-based compensation expense					1,221,591		1,221,591
Net loss						(18,369,810)	(18,369,810)
Balance (in shares) at Dec. 31, 2018				3,376,230
Balance at Dec. 31, 2018				$ 3,377	95,532,881	(79,924,699)	15,611,559
Stock-based compensation expense					515,762		515,762
Net loss						(11,799,379)	(11,799,379)
Issuance of common stock, pre-funded warrants and warrants, net of issuance costs (in shares)				12,688,276
Issuance of common stock, pre-funded warrants and warrants, net of issuance costs				$ 12,688	11,905,207		11,917,895
Proceeds from warrants (in shares)	17,415,859
Proceeds from warrants	$ 17,416	$ 3,888,425
Balance (in shares) at Dec. 31, 2019				33,480,365
Balance at Dec. 31, 2019				$ 33,481	$ 111,824,859	$ (91,724,078)	$ 20,134,262

Consolidated Statements of Cash Flow - USD ($)	12 Months Ended
Consolidated Statements of Cash Flow - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (11,799,379)	$ (18,369,810)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	97,915	110,371
Stock-based compensation expense	515,762	1,221,591
Common stock issued for advisory services		50,000
Change in deferred income taxes	332,885	(437,289)
Goodwill impairment		6,929,258
Changes in operating assets and liabilities:
Prepaid expenses, deposits and other assets	426,774	(1,102)
Accounts payable, accrued expenses and other liabilities	567,668	(275,835)
Net cash used in operating activities	(9,858,375)	(10,772,816)
Cash flows provided by financing activities:
Proceeds from sale of common stock, pre-funded warrants and warrants	12,318,956	10,846,062
Proceeds from the exercise of common stock warrants and pre-funded warrants	3,888,425
Repayment of convertible debt		(550,000)
Payment of offering costs	(162,829)	(428,542)
Net cash provided by financing activities	16,044,552	9,867,520
Net increase (decrease) in cash and cash equivalents	6,186,177	(905,296)
Cash and cash equivalents at beginning of year	7,991,172	8,896,468
Cash and cash equivalents at end of year	14,177,349	7,991,172
Supplemental disclosure of cash flow information:
Cash paid for interest		40,142
Supplemental disclosure of non-cash investing and financing activities:
Offering costs in accounts payable and accrued expenses	238,232
Operating lease right of use asset and liability	334,205
Reclassification of accrued dividends related to the issuance of common stock to Series A convertible preferred stock holders		1,148,307
Series A cumulative preferred dividends		$ 85,993

Note 1 - Organization and Description of Business	12 Months Ended
Note 1 - Organization and Description of Business	Dec. 31, 2019
Notes to Financial Statements
Nature of Operations [Text Block]	1. Organization and Description of Business Diffusion Pharmaceuticals Inc. (“Diffusion” or the “Company”), a Delaware corporation, is a clinical stage biotechnology company developing new treatments for life-threatening conditions by improving the body’s ability to bring oxygen to the areas where it is needed most. The Company is developing its lead product candidate, transcrocetinate sodium, also known as trans sodium crocetinate (“TSC”), for use in those life-threatening conditions in which cellular oxygen deprivation (“hypoxia”) is the basis for significant unmet medical needs. TSC is designed to safely and selectively target and re-oxygenate the micro-environment of hypoxic cells, and can potentially be used in many indications, including stroke, oncology and cardiovascular disease. In stroke, TSC helps promote the diffusion of oxygen into those brain cells in which oxygen-deprivation causes neuronal death resulting in patient mortality or morbidity. In cancer, TSC re-oxygenates treatment-resistant cancerous tissue, making the cancer cells up to three times more susceptible to the therapeutic effects of standard-of-care radiation therapy and chemotherapy. In addition to the TSC programs, the Company is exploring alternatives regarding how best to capitalize upon our product candidate RES- 529, which may include possible out-licensing and other options. RES- 529 is a novel PI3K/Akt/mTOR pathway inhibitor which has completed two Phase 1 clinical trials for age-related macular degeneration and is in preclinical development in oncology, specifically GBM. RES- 529 has shown activity in both in vitro and in vivo glioblastoma animal models and has been demonstrated to be orally bioavailable and capable of crossing the blood brain barrier.

Note 2 - Liquidity	12 Months Ended
Note 2 - Liquidity	Dec. 31, 2019
Notes to Financial Statements
Liquidity Disclosure [Text Block]	2. Liquidity The Company has not generated any revenues from product sales and has funded operations primarily from the proceeds of public and private offerings of equity, convertible debt and convertible preferred stock. Substantial additional financing will be required by the Company to continue to fund its research and development activities. No assurance can be given that any such financing will be available when needed or that the Company’s research and development efforts will be successful. The Company regularly explores alternative means of financing its operations and seeks funding through various sources, including public and private securities offerings, collaborative arrangements with third parties and other strategic alliances and business transactions. During 2019, the Company raised approximately $16.0 million in three separate financings, including the proceeds from the exercise of warrants issued in such financing. See Note 7 for further details. The Company currently does not have any commitments to obtain additional funds and may be unable to obtain sufficient funding in the future on acceptable terms, if at all. If the Company cannot obtain the necessary funding, it will need to delay, scale back or eliminate some or all of its research and development programs or enter into collaborations with third parties to: commercialize potential products or technologies that it might otherwise seek to develop or commercialize independently; consider other various strategic alternatives, including a merger or sale of the Company; or cease operations. If the Company engages in collaborations, it may receive lower consideration upon commercialization of such products than if it had not entered into such arrangements or if it entered into such arrangements at later stages in the product development process. The Company has prepared its financial statements assuming that it will continue as a going concern, which contemplates realization of assets and the satisfaction of liabilities in the normal course of business. The Company has incurred net losses since inception and it expects to generate losses from operations for the foreseeable future primarily due to research and development costs for its potential product candidates, which raises substantial doubt about the Company’s ability to continue as a going concern. The Company currently has no sources of revenue and its ability to continue as a going concern is dependent on its ability to raise capital to fund its future business plans. Additionally, volatility in the capital markets and general economic conditions in the United States may be a significant obstacle to raising the required funds. These factors raise substantial doubt about its ability to continue as a going concern. The financial statements included herein do not include any adjustments that might be necessary should the Company be unable to continue as a going concern. If the going concern basis were not appropriate for these financial statements, adjustments would be necessary in the carrying value of assets and liabilities, the reported expenses and the balance sheet classifications used. Operations of the Company are subject to certain risks and uncertainties including various internal and external factors that will affect whether and when the Company’s product candidates become approved drugs and how significant their market share will be, some of which are outside of the Company’s control. The length of time and cost of developing and commercializing these product candidates and/or failure of them at any stage of the drug approval process will materially affect the Company’s financial condition and future operations. The Company believes its cash and cash equivalents as of December 31, 2019 are sufficient to fund operations into January of 2021.

Note 3 - Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Significant Accounting Policies [Text Block]

Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements of the Company have been prepared in accordance with US GAAP. Any reference in these notes to applicable guidance is meant to refer to US GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Use of Estimates

The preparation of financial statements in conformity with US GAAP requires the Company 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 financial statements and the reported amounts of expenses during the reporting period.

On an ongoing basis, the Company evaluates its estimates using historical experience and other factors, including the current economic environment. Significant items subject to such estimates are assumptions used for purposes of determining stock-based compensation and accounting for research and development activities. Management believes its estimates to be reasonable under the circumstances. Actual results could differ significantly from those estimates.

Fair Value of Financial Instruments

Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The carrying amounts of certain of the Company’s financial instruments, including cash equivalents and accounts payable are shown at cost, which approximates fair value due to the short-term nature of these instruments. The Company follows the provisions of FASB ASC Topic

820,

Fair Value Measurement

, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in

one

of the following

three

categories:

•

Level

Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

•

Level

Quoted prices in markets that are

not

active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities.

•

Level

Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or

market activity).

The following fair value hierarchy table presents information about the Company’s cash equivalents measured at fair value on a recurring basis:

	Fair value measurement at reporting date using
(in thousands)	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
December 31, 2019:
Assets:
Cash equivalents	$	14,006,193	$	—	$	—
December 31, 2018:
Assets:
Cash equivalents	$	7,990,900	$	—	$	—

Concentration of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash on deposit with multiple financial institutions, the balances of which frequently exceed federally insured limits.

Cash and Cash Equivalents

The Company considers any highly liquid investments, such as money market funds, with an original maturity of

three

months or less to be cash and cash equivalents.

Property and Equipment

The Company records property and equipment at cost less accumulated depreciation and amortization. Costs of renewals and improvements that extend the useful lives of the assets are capitalized. Maintenance and repairs are expensed as incurred. Depreciation is recognized on a straight-line basis over the estimated useful lives of the assets, which generally range from

years. The Company amortizes leasehold improvements over the shorter of the estimated useful life of the asset or the term of the related lease. Upon retirement or disposition of assets, the costs and related accumulated depreciation and amortization are removed from the accounts with the resulting gains or losses, if any, reflected in results of operations.

Long-Lived Assets

Long-lived assets are reviewed for potential impairment whenever events indicate that the carrying amount of such assets

may

not

be recoverable. The Company does this by comparing the carrying value of the long-lived assets with the estimated future undiscounted cash flows expected to result from the use of the assets, including cash flows from disposition. If it is determined an impairment exists, the asset is written down to its estimated fair value. The Company has

not

recognized any impairment of long-lived assets during the years ended

December 31, 2019

and

2018.

Intangible Asset

The Company has an indefinite-lived In-Process Research and Development Asset (IPR&D) called RES-

529,

which has a balance of

$8.6

million at both

December 31, 2019

and

December 31, 2018.

RES-

529

is a

PI3K/Akt/mTOR

pathway inhibitor in preclinical development for oncology.

Intangible assets deemed to have indefinite lives are

not

amortized but rather are assessed for impairment annually on

October 1

of the Company’s fiscal year or more frequently if impairment indicators exist. There was

impairment to the Company’s RES-

529

intangible asset recognized during the years ended

December 31, 2019

and

2018.

Leases

February 2016,

the FASB issued a new standard related to leases to increase transparency and comparability among organizations by requiring the recognition of operating lease right-of-use (“ROU”) assets and lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. See Note

for further details.

Research and Development

Major components of research and development costs include internal research and development (such as salaries and related employee benefits, equity-based compensation, supplies and allocated facility costs) and contracted services (research and development activities performed on the Company’s behalf). Costs incurred for research and development are expensed as incurred.

At the end of the reporting period, the Company compares payments made to

third

-party service providers to the estimated progress toward completion of the research or development objectives. Such estimates are subject to change as additional information becomes available. Depending on the timing of payments to the service providers and the progress that the Company estimates has been made as a result of the services provided, the Company

may

record net prepaid or accrued expenses relating to these costs.

Upfront payments made to

third

parties who perform research and development services on the Company’s behalf are expensed as services are rendered.

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and are recorded within general and administrative expenses in the statements of operations.

Income Taxes

As a corporation, the Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided when it is more likely than

not

that some portion or all of a deferred tax asset will

not

be realized. The Company recognizes the benefit of an uncertain tax position that it has taken or expects to take on its income tax return it files, if such a position is more likely than

not

to be sustained.

Stock-based Compensation

The Company measures stock-based awards at grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the award. The Company uses the Black-Scholes option pricing model to value its stock option awards. Estimating the fair value of stock option awards requires management to apply judgment and make estimates, including the volatility of the Company’s common stock, the expected term of the Company’s stock options, the expected dividend yield and the fair value of the Company’s common stock on the measurement date. As a result, if factors change and management uses different assumptions, stock-based compensation expense could be materially different for future awards.

The expected term of stock options was estimated using the “simplified method” for employee options as the Company has

historical information to develop reasonable expectations about future exercise patterns and post vesting employment termination behavior for its stock option grants. The simplified method is based on the average of the vesting tranches and the contractual life of each grant. For options granted to non-employees, the Company uses the remaining contractual life. For stock price volatility, the Company uses a combination of their own historical stock price and comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The Company assumes

dividend yield because dividends are

not

expected to be paid in the near future, which is consistent with the Company’s history of

not

paying dividends. The risk-free interest rate is based on U.S. Treasury notes with a term approximating the expected life of the option. The Company accounts for forfeitures in the periods they occur.

Net Loss Per Common Share

Basic net loss per share is computed by dividing net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during each period. Diluted net loss per share includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock, common stock warrants, stock options and unvested restricted stock that would result in the issuance of incremental shares of common stock. In computing the basic and diluted net loss per share applicable to common stockholders, the weighted average number of shares remains the same for both calculations due to the fact that when a net loss exists, dilutive shares are

not

included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti-dilutive:

	December 31,
	2019		2018
Common stock warrants		22,385,141		2,087,012
Stock options		309,276		203,736
		22,694,417		2,290,748

Recently Issued But

Not

Yet Adopted Accounting Pronouncements

August 2018,

the FASB issued ASU

2018

03,

Disclosure Framework- Changes to the Disclosure Requirements for Fair Value Measurements,

which changes the fair value measurement disclosure requirements of ASC

820.

The goal of the ASU is to improve the effectiveness of ASC

820's

disclosure requirements. The guidance is applicable to public business entities for fiscal years beginning after

December 15, 2019

and interim periods within those years. The Company does

not

believe that the adoption of this standard will have a material impact on its related disclosures.

Recently Adopted Accounting Pronouncements

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

to increase transparency and comparability among organizations by requiring the recognition of operating lease right-of-use assets and lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under ASC

842,

disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases.

The Company adopted ASC

842,

effective

January 1, 2019

using a modified retrospective approach and elected to apply the available practical expedients. The standard had an impact on the Company’s consolidated balance sheet but did

not

have an impact on the Company’s consolidated statements of operations or consolidated statements of cash flows upon adoption. The most significant impact of ASC

842

was the recognition of a

$0.3

million ROU asset and corresponding lease liability for the Company's single operating lease.

January 1, 2019,

the Company adopted ASU

2018

07,

Compensation—Stock Compensation (Topic

718

): Improvements to Non-employee Share-Based Payment Accounting

(“ASU

No.

2018

07”

) which simplifies the accounting for share-based payments granted to non-employees for goods and services. The ASU supersedes ASC

505

Equity-based Payments to Non-employees

and expands the scope of ASC

718

to include all share-based payment arrangements related to the acquisition of goods and services from both non-employees and employees. The adoption of ASU

No.

2018

did

not

have an impact on the consolidated financial statements of the Company.

Note 4 - Property and Equipment

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Property, Plant and Equipment Disclosure [Text Block]

Property and Equipment

Property and equipment consists of the following:

	December 31,
	2019			2018
Laboratory equipment	$	182,357		$	182,357
Furniture and office equipment		151,442			155,113
Leasehold improvements		430,000			430,000
Total property and equipment		763,799			767,470
Less: accumulated depreciation		(511,433	)		(417,189	)
Property and equipment, net	$	252,366		$	350,281

Depreciation expense was approximately

$0.1

million for both the years ended

December 31, 2019

and

2018,

respectively.

Note 5 - Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:

	December 31,
	2019		2018
Accrued payroll and payroll related expenses	$	182,708	$	409,889
Accrued professional fees		48,338		69,231
Accrued clinical studies expenses		57,378		34,000
Other		70,108		92,106
Total	$	358,532	$	605,226

Note 6 - Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Commitments and Contingencies Disclosure [Text Block]

Commitments and Contingencies

Office Space Lease Commitment

The Company has a non-cancelable operating lease for office and laboratory space in Charlottesville, Virginia, which began in

April 2017

and, as of

December 31, 2019,

has a remaining lease term of approximately

2.3

years. As disclosed in Note

the Company adopted ASC

842

in the

first

quarter of

2019

and as a result of the adoption, the Company recognized a current operating lease liability of

$0.1

million and a noncurrent operating lease liability of

$0.2

million with a corresponding ROU asset of the combined amounts, which is based on the present value of the minimum rental payments of the lease. The discount rate used to account for the Company's operating lease under ASC

842

is the Company’s estimated incremental borrowing rate of

10%.

The original term of the lease ends in the

second

quarter of

2022

and the Company has an option to extend for another

years. This option to extend was

not

recognized as part of the Company's measurement of the ROU asset and operating lease liability as of

December 31, 2019.

Rent expense related to the Company's operating lease for both the years ended

December

31,

2019

and

2018

was approximately

$0.1

million. Future minimum rental payments under the Company's non-cancelable operating lease at

December

31,

2019

were as follows:

	Rental Commitments
2020	$	116,464
2021		118,519
2022		39,735
Total		274,718
Less: imputed interest		(27,675	)
	$	247,043

Future minimum rental payments under the Company's non-cancelable operating lease was as follows as of

December 31, 2018:

	Rental Commitments
2019	$	114,409
2020		116,464
2021		118,519
2022		39,735
Total	$	389,127

Research and Development Arrangements

In the course of normal business operations, the Company enters into agreements with universities and contract research organizations, or CROs, to assist in the performance of research and development activities and contract manufacturers to assist with chemistry, manufacturing, and controls related expenses. Expenditures to CROs represent a significant cost in clinical development for the Company. The Company could also enter into additional collaborative research, contract research, manufacturing, and supplier agreements in the future, which

may

require upfront payments and long-term commitments of cash.

Defined Contribution Retirement Plan

The Company has established a

401

(k) defined contribution plan (the

401

(k) Plan) that covers all employees who qualify under the terms of the plan. Eligible employees

may

elect to contribute to the

401

(k) Plan up to

90%

of their compensation, limited by the IRS-imposed maximum. The Company provides a safe harbor match with a maximum amount of

of the participant’s compensation. The Company made matching contributions under the

401

(k) Plan of approximately

$68,000

for both the years ended

December

31,

2019

and

2018.

Legal Proceedings

August 7, 2014,

a complaint was filed in the Superior Court of Los Angeles County, California by Paul Feller, the Company’s former Chief Executive Officer under the caption

Paul Feller v. RestorGenex Corporation, Pro Sports & Entertainment, Inc., ProElite, Inc. and Stratus Media Group, GmbH

(Case

No.

BC553996

). The complaint asserts various causes of action, including, among other things, promissory fraud, negligent misrepresentation, breach of contract, breach of employment agreement, breach of the covenant of good faith and fair dealing, violations of the California Labor Code and common counts. The plaintiff is seeking, among other things, compensatory damages in an undetermined amount, punitive damages, accrued interest and an award of attorneys’ fees and costs. On

December 30, 2014,

the Company filed a petition to compel arbitration and a motion to stay the action. On

April 1, 2015,

the plaintiff filed a petition in opposition to the Company’s petition to compel arbitration and a motion to stay the action. After a hearing for the petition and motion on

April 14, 2015,

the Court granted the Company’s petition to compel arbitration and a motion to stay the action. On

January 8, 2016,

the plaintiff filed an arbitration demand with the American Arbitration Association. On

November 19, 2018

at an Order to Show Cause Re Dismissal Hearing, the Court found sufficient grounds

not

to dismiss the case, and an arbitration hearing has been scheduled for

November 2020.

The Company believes this matter is without merit and intends to defend the arbitration vigorously. Because this matter is in an early stage, the Company is unable to predict its outcome and the possible loss or range of loss, if any, associated with its resolution or any potential effect the matter

may

have on the Company’s financial position. Depending on the outcome or resolution of this matter, it could have a material effect on the Company’s financial position.

Note 7 - Stockholders' Equity and Common Stock Warrants

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

Stockholders' Equity and Common Stock Warrants

2019

Common Stock Offerings

December 2019,

Company completed an offering (the

“December 2019

Offering”) of

6,266,787

shares of its common stock and warrants to purchase

6,266,787

shares of common stock. The shares of common stock and warrants were sold for a combined purchase price of

$0.5585

per share for net proceeds of

$3.0

million. The

December 2019

Offering warrants are exercisable beginning on the date of their issuance until

June 13, 2025

at an initial exercise price equal to

$0.4335

per share.

In addition, at the closing of the

December 2019

Offering, the Company issued warrants to purchase up to

313,339

shares of common stock to designees of the placement agent. The placement agent's warrants have an exercise price of

$0.6981

per share and a term of

five

years from the date of issuance.

November 2019,

the Company completed a registered direct public offering (the

“November 2019

Offering”) of

5,104,429

shares of its common stock, and

6,324,143

pre-funded warrants each to purchase

one

share of common stock, together with warrants to purchase up to

22,857,144

shares of common stock at a combined public offering price of

$0.35

per share and associated warrants for total net proceeds of

$3.3

million. The warrants were issued with an exercise price of

$0.35

per warrant and are exercisable beginning on their date of issuance. Of the warrants issued,

11,428,572

have a term of

months and

11,428,572

have a term of

years. During the year ended

December 31, 2019,

11,091,716

of those warrants were exercised for proceeds of

$3.9

million.

In addition, at the closing of the

November 2019

Offering, the Company issued warrants to purchase up to

571,429

shares of common stock to designees of the placement agent. The placement agent's warrants have an exercise price of

$0.4375

per share and a term of

five

years from the date of issuance.

May 2019,

the Company completed a registered direct public offering (the

“May 2019

Offering”) of

1,317,060

shares of common stock and a private placement of warrants to purchase

1,317,060

shares of common stock. The shares of common stock and warrants were sold for a combined purchase price of

$4.895

for total net proceeds of

$5.6

million. The warrants are exercisable beginning on the date of their issuance until

November 29, 2024

at an initial exercise price equal to

$5.00.

In addition, at the closing of the

May 2019

Offering, the Company issued warrants to purchase up to

65,853

shares of common stock to designees of the placement agent. The placement agent's warrants have an exercise price of

$6.11875

per share and a term of

years from the date of issuance.

2018

Common Stock Offering

January 2018,

the Company entered into an Underwriting Agreement (the “Agreement”) pursuant to which it issued

1,000,000

shares of common stock and warrants to purchase

1,000,000

shares of common stock with an initial exercise price of

$12.00

per share for cash proceeds of

$10.8

million. In addition, as compensation for its services, the Company granted to the underwriter in the transaction an option (the “Over-Allotment Option”) to purchase, in the aggregate,

150,000

shares of common stock (the “Option Shares”) and warrants to purchase up to

150,000

shares of common stock (the “Option Warrants”). The underwriter exercised its right to purchase a portion of the Option Warrants and received an additional

131,375

warrants to purchase common stock with an initial exercise price

$12.00

per share.

In addition, at the closing, the Company issued to designees of the underwriter warrants to purchase up to

50,000

shares of common stock. The underwriter’s warrants have an exercise price of

$15.00

per share and a term of

five

years from the date of issuance.

As a result of the Company's common stock offering in

January 2018,

all outstanding shares of the Company's Series A convertible preferred stock converted into

1,400,462

shares of common stock of which (i)

553,752

shares were issued for the automatic conversion of Series A convertible preferred stock (ii)

68,815

shares were issued upon settlement of accrued dividends and (iii)

777,895

shares were issued for the settlement of the “make-whole” adjustment feature. A deemed dividend of

$8.2

million was recognized for the value of the common shares issued for the settlement of the make-whole adjustment feature.

Common Stock Warrants

During its evaluation of equity classification for the Company's common stock warrants issued in

2019

and

2018,

the Company considered the conditions as prescribed within ASC

815

40,

Derivatives and Hedging, Contracts in an Entity’s own Equity

(“ASC

815

40”

). The conditions within ASC

815

are

not

subject to a probability assessment. The warrants do

not

fall under the liability criteria within ASC

480

Distinguishing Liabilities from Equity

as they are

not

puttable and do

not

represent an instrument that has a redeemable underlying security. The warrants do meet the definition of a derivative instrument under ASC

815,

but are eligible for the scope exception as they are indexed to the Company’s own stock and would be classified in permanent equity if freestanding.

As of

December

31,

2019,

the Company had the following warrants outstanding to acquire shares of its common stock:

	Outstanding		Range of exercise price per share			Expiration dates
Common stock warrants issued in 2017 related to Series A convertible preferred stock offering		903,870		$33.30		March 2022
Common stock warrants issued in 2018 related to the common stock offering		1,181,375	$12.00	-	$15.00	January 2023
Common stock warrants issued related to the May 2019 Offering		1,382,913	$5.00	-	$6.11875	May and December 2024
Common stock warrants issued related to the November 2019 Offering		12,336,857	$0.35	-	$0.4375	May 2024
Common stock warrants issued related to the December 2019 Offering		6,580,126	$0.4335	-	$0.6981	December 2024 and June 2025
		22,385,141

During the years ended

December

31,

2019

and

2018,

1,767

and

28,123

warrants expired, respectively.

Note 8 - Stock-based Compensation

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Share-based Payment Arrangement [Text Block]

Stock-Based Compensation

2015

Equity Plan

The Diffusion Pharmaceuticals Inc.

2015

Equity Incentive Plan, as amended (the

"2015

Equity Plan"), provides for increases to the number of shares reserved for issuance thereunder each

January 1

equal to

4.0%

of the total shares of the Company’s common stock outstanding as of the immediately preceding

December 31,

unless a lesser amount is stipulated by the Compensation Committee of the Company's board of directors. Accordingly,

1,339,215

shares were added to the reserve as of

January 1, 2020,

which shares

may

be issued in connection with the grant of stock-based awards, including stock options, restricted stock, restricted stock units, stock appreciation rights and other types of awards as deemed appropriate, in each case, in accordance with the terms of the

2015

Equity Plan. As of

December

31,

2019,

there were

19,740

shares of common stock available for future issuance under the

2015

Equity Incentive Plan. Generally, the options have a

ten

(

) year contractual term and vest in equal monthly installments over

three

(

) years.

The Company recorded stock-based compensation expense in the following expense categories of its consolidated statements of operations for the periods indicated:

	Year ended December 31,
	2019		2018
Research and development	$	54,155	$	62,161
General and administrative		461,607		1,159,430
Total stock-based compensation expense	$	515,762	$	1,221,591

The following table summarizes the activity related to all stock option:

	Number of Options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate Intrinsic Value
Balance at January 1, 2018		170,461		$	109.74
Granted		44,005			15.37
Forfeited		(10,583	)		131.25
Expired		(147	)		256.50
Balance at January 1, 2019		203,736		$	88.14		6.70	$	143
Granted		117,270			2.62
Forfeited		(11,583	)		83.81
Expired		(147	)		276.00
Outstanding at December 31, 2019		309,276		$	55.78		6.98	$	—
Exercisable at December 31, 2019		235,415		$	71.75		6.34	$	—
Vested and expected to vest at December 31, 2019		309,276		$	55.78		6.98	$	—

The weighted average grant date fair value of stock option awards granted was

$2.16

and

$12.63

during the years ended

December

31,

2019

and

2018,

respectively. The total fair value of options vested during the years ended

December

31,

2019

and

2018

were

$0.6

million and

$1.2

million, respectively.

options were exercised during any of the periods presented. At

December

31,

2019,

there was

$0.3

million of unrecognized compensation cost related to unvested options that will be recognized as expense over a weighted-average period of

1.06

years.

The grant date fair value of employee stock options is determined using the Black-Scholes model. The following assumptions were used during the years ended

December

31,

2019

and

2018:

	2019						2018
Expected term (in years)		5.25		—	5.77			5.27		—	5.66
Risk-free interest rate		1.9	%	—	2.5	%		2.3	%	—	2.8	%
Expected volatility		112.4	%	—	114.4	%		113.6	%	—	115.0	%
Dividend yield		—		—	—			—		—	—

Note 9 - Income Taxes

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Income Tax Disclosure [Text Block]

Income Taxes

Since inception, the Company has incurred net losses, and until

2018,

had

not

recorded any U.S. federal or state income tax benefits for the losses. In

2018,

as a result of the change in net operating loss carryforward period associated with the Tax Cuts and Jobs Act ("the

2017

Tax Act"), the Company recognized an income tax benefit to reflect the adjustment allowed by the

2017

Tax Act to utilize indefinite deferred tax liabilities as a source of income against indefinite lived portions of the Company’s deferred tax assets. In

2019,

as a result of a change in ownership under the provisions of Internal Revenue Code Section

382,

the cumulative benefit of net operating losses was remeasured which resulted in tax expense to reverse the

2018

benefit recorded and record a benefit relative to losses incurred in

2019

after the date of the change in ownership.

Deferred tax assets and liabilities are determined based on the differences between the financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for years in which differences are expected to reverse.

Significant components of the Company's deferred tax assets for federal income taxes consisted of the following:

Deferred tax assets	December 31, 2019			December 31, 2018
Net operating loss carryforwards	$	1,504,496		$	5,875,074
Stock option compensation		1,381,750			2,456,410
Orphan Drug credits		81,700			2,847,803
Lease liability		63,589
Capitalized start-up costs and other		9,187,898			7,349,092
Valuation allowance		(12,051,440	)		(18,091,090	)
Deferred tax assets		167,993			437,289

Deferred tax liabilities
Intangible assets		(2,223,678	)		(2,223,678	)
Right of use asset		(63,589	)		—
Deferred tax liabilities		(2,287,267	)		(2,223,678	)

Net deferred tax liability	$	(2,119,274	)	$	(1,786,389	)

The Company does

not

have unrecognized tax benefits as of

December

31,

2019

December 31, 2018.

The Company's policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense.

The Company had net operating loss carryforwards (“NOL”) for federal and state income tax purposes at

December

31,

2019

and

2018

of approximately:

Combined NOL Carryforwards:	December 31, 2019		December 31, 2018
Federal	$	5,844,972	$	22,819,972
State		5,844,972		22,845,568

The pre-

2018

net operating loss carryforwards begin expiring in

2020

for both federal and state income tax purposes. In

November 2019,

as a result of a change of ownership under the provisions of Internal Revenue Code Section

382

and similar state provisions, the Company’s ability to utilize their net operating loss carryforwards to offset future income was limited. The Company recorded a valuation allowance against a portion of their deferred tax assets as of

December 31, 2019

because of the uncertainty of their realization.

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

Rate reconciliation:	December 31, 2019			December 31, 2018
Federal tax benefit at statutory rate		(21.0	)%		(21.0	)%
State tax, net of Federal benefit		(2.5	)%		(2.9	)%
Goodwill impairment		—	%		7.7	%
Orphan drug credit		25.3	%		(1.3	)%
Change in valuation allowance		(7.5	)%		15.2	%
Stock compensation		8.6	%		—	%
Other		0.1	%		—	%
Total provision		3.0	%		(2.3	)%

The Company files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. The Company’s

2016

2018

tax years remain open and subject to examination.

Note 10 - Related Party Transactions	12 Months Ended
Note 10 - Related Party Transactions	Dec. 31, 2019
Notes to Financial Statements
Related Party Transactions Disclosure [Text Block]	10. Related Party Transactions The Company’s Director of Information Technologies is the son of the Chief Executive Officer and he has held that position since December 2014.

Note 11 - Subsequent Event	12 Months Ended
Note 11 - Subsequent Event	Dec. 31, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	11. Subsequent Event Through March 17, 2020, 1,124,071 warrants were exercised at $0.35 per warrant resulting in proceeds received of $0.4 million.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value of Financial Instruments

820,

Fair Value Measurement

, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in

one

of the following

three

categories:

•

Level

Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

•

Level

Quoted prices in markets that are

not

active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities.

•

Level

Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or

market activity).

The following fair value hierarchy table presents information about the Company’s cash equivalents measured at fair value on a recurring basis:

	Fair value measurement at reporting date using
(in thousands)	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
December 31, 2019:
Assets:
Cash equivalents	$	14,006,193	$	—	$	—
December 31, 2018:
Assets:
Cash equivalents	$	7,990,900	$	—	$	—

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Credit Risk

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

The Company considers any highly liquid investments, such as money market funds, with an original maturity of

three

months or less to be cash and cash equivalents.

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Long-Lived Assets

Long-lived assets are reviewed for potential impairment whenever events indicate that the carrying amount of such assets

may

not

recognized any impairment of long-lived assets during the years ended

December 31, 2019

and

2018.

Goodwill and Intangible Assets, Policy [Policy Text Block]

Intangible Asset

The Company has an indefinite-lived In-Process Research and Development Asset (IPR&D) called RES-

529,

which has a balance of

$8.6

million at both

December 31, 2019

and

December 31, 2018.

RES-

529

is a

PI3K/Akt/mTOR

pathway inhibitor in preclinical development for oncology.

Intangible assets deemed to have indefinite lives are

not

amortized but rather are assessed for impairment annually on

October 1

of the Company’s fiscal year or more frequently if impairment indicators exist. There was

impairment to the Company’s RES-

529

intangible asset recognized during the years ended

December 31, 2019

and

2018.

Lessee, Leases [Policy Text Block]

Leases

February 2016,

for further details.

Research and Development Expense, Policy [Policy Text Block]

Research and Development

At the end of the reporting period, the Company compares payments made to

third

may

record net prepaid or accrued expenses relating to these costs.

Upfront payments made to

third

parties who perform research and development services on the Company’s behalf are expensed as services are rendered.

Legal Costs, Policy [Policy Text Block]

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and are recorded within general and administrative expenses in the statements of operations.

Income Tax, Policy [Policy Text Block]

Income Taxes

not

that some portion or all of a deferred tax asset will

not

be realized. The Company recognizes the benefit of an uncertain tax position that it has taken or expects to take on its income tax return it files, if such a position is more likely than

not

to be sustained.

Share-based Payment Arrangement [Policy Text Block]

Stock-based Compensation

The expected term of stock options was estimated using the “simplified method” for employee options as the Company has

dividend yield because dividends are

not

expected to be paid in the near future, which is consistent with the Company’s history of

not

Earnings Per Share, Policy [Policy Text Block]

Net Loss Per Common Share

not

included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti-dilutive:

	December 31,
	2019		2018
Common stock warrants		22,385,141		2,087,012
Stock options		309,276		203,736
		22,694,417		2,290,748

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Issued But

Not

Yet Adopted Accounting Pronouncements

August 2018,

the FASB issued ASU

2018

03,

Disclosure Framework- Changes to the Disclosure Requirements for Fair Value Measurements,

which changes the fair value measurement disclosure requirements of ASC

820.

The goal of the ASU is to improve the effectiveness of ASC

820's

disclosure requirements. The guidance is applicable to public business entities for fiscal years beginning after

December 15, 2019

and interim periods within those years. The Company does

not

believe that the adoption of this standard will have a material impact on its related disclosures.

Recently Adopted Accounting Pronouncements

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

842,

disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases.

The Company adopted ASC

842,

effective

January 1, 2019

using a modified retrospective approach and elected to apply the available practical expedients. The standard had an impact on the Company’s consolidated balance sheet but did

not

have an impact on the Company’s consolidated statements of operations or consolidated statements of cash flows upon adoption. The most significant impact of ASC

842

was the recognition of a

$0.3

million ROU asset and corresponding lease liability for the Company's single operating lease.

January 1, 2019,

the Company adopted ASU

2018

07,

Compensation—Stock Compensation (Topic

718

): Improvements to Non-employee Share-Based Payment Accounting

(“ASU

No.

2018

07”

) which simplifies the accounting for share-based payments granted to non-employees for goods and services. The ASU supersedes ASC

505

Equity-based Payments to Non-employees

and expands the scope of ASC

718

to include all share-based payment arrangements related to the acquisition of goods and services from both non-employees and employees. The adoption of ASU

No.

2018

did

not

have an impact on the consolidated financial statements of the Company.

Note 3 - Basis of Presentation and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	Fair value measurement at reporting date using
(in thousands)	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
December 31, 2019:
Assets:
Cash equivalents	$	14,006,193	$	—	$	—
December 31, 2018:
Assets:
Cash equivalents	$	7,990,900	$	—	$	—

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	December 31,
	2019		2018
Common stock warrants		22,385,141		2,087,012
Stock options		309,276		203,736
		22,694,417		2,290,748

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Note 4 - Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Property, Plant and Equipment [Table Text Block]

	December 31,
	2019			2018
Laboratory equipment	$	182,357		$	182,357
Furniture and office equipment		151,442			155,113
Leasehold improvements		430,000			430,000
Total property and equipment		763,799			767,470
Less: accumulated depreciation		(511,433	)		(417,189	)
Property and equipment, net	$	252,366		$	350,281

Note 5 - Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Other Current Liabilities [Table Text Block]

	December 31,
	2019		2018
Accrued payroll and payroll related expenses	$	182,708	$	409,889
Accrued professional fees		48,338		69,231
Accrued clinical studies expenses		57,378		34,000
Other		70,108		92,106
Total	$	358,532	$	605,226

Note 6 - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Lessee, Operating Lease, Liability, Maturity [Table Text Block]

	Rental Commitments
2020	$	116,464
2021		118,519
2022		39,735
Total		274,718
Less: imputed interest		(27,675	)
	$	247,043

	Rental Commitments
2019	$	114,409
2020		116,464
2021		118,519
2022		39,735
Total	$	389,127

Note 7 - Stockholders' Equity and Common Stock Warrants (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Outstanding		Range of exercise price per share			Expiration dates
Common stock warrants issued in 2017 related to Series A convertible preferred stock offering		903,870		$33.30		March 2022
Common stock warrants issued in 2018 related to the common stock offering		1,181,375	$12.00	-	$15.00	January 2023
Common stock warrants issued related to the May 2019 Offering		1,382,913	$5.00	-	$6.11875	May and December 2024
Common stock warrants issued related to the November 2019 Offering		12,336,857	$0.35	-	$0.4375	May 2024
Common stock warrants issued related to the December 2019 Offering		6,580,126	$0.4335	-	$0.6981	December 2024 and June 2025
		22,385,141

Note 8 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Year ended December 31,
	2019		2018
Research and development	$	54,155	$	62,161
General and administrative		461,607		1,159,430
Total stock-based compensation expense	$	515,762	$	1,221,591

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate Intrinsic Value
Balance at January 1, 2018		170,461		$	109.74
Granted		44,005			15.37
Forfeited		(10,583	)		131.25
Expired		(147	)		256.50
Balance at January 1, 2019		203,736		$	88.14		6.70	$	143
Granted		117,270			2.62
Forfeited		(11,583	)		83.81
Expired		(147	)		276.00
Outstanding at December 31, 2019		309,276		$	55.78		6.98	$	—
Exercisable at December 31, 2019		235,415		$	71.75		6.34	$	—
Vested and expected to vest at December 31, 2019		309,276		$	55.78		6.98	$	—

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2019						2018
Expected term (in years)		5.25		—	5.77			5.27		—	5.66
Risk-free interest rate		1.9	%	—	2.5	%		2.3	%	—	2.8	%
Expected volatility		112.4	%	—	114.4	%		113.6	%	—	115.0	%
Dividend yield		—		—	—			—		—	—

Note 9 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred tax assets	December 31, 2019			December 31, 2018
Net operating loss carryforwards	$	1,504,496		$	5,875,074
Stock option compensation		1,381,750			2,456,410
Orphan Drug credits		81,700			2,847,803
Lease liability		63,589
Capitalized start-up costs and other		9,187,898			7,349,092
Valuation allowance		(12,051,440	)		(18,091,090	)
Deferred tax assets		167,993			437,289

Deferred tax liabilities
Intangible assets		(2,223,678	)		(2,223,678	)
Right of use asset		(63,589	)		—
Deferred tax liabilities		(2,287,267	)		(2,223,678	)

Net deferred tax liability	$	(2,119,274	)	$	(1,786,389	)

Summary of Operating Loss Carryforwards [Table Text Block]

Combined NOL Carryforwards:	December 31, 2019		December 31, 2018
Federal	$	5,844,972	$	22,819,972
State		5,844,972		22,845,568

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

Rate reconciliation:	December 31, 2019			December 31, 2018
Federal tax benefit at statutory rate		(21.0	)%		(21.0	)%
State tax, net of Federal benefit		(2.5	)%		(2.9	)%
Goodwill impairment		—	%		7.7	%
Orphan drug credit		25.3	%		(1.3	)%
Change in valuation allowance		(7.5	)%		15.2	%
Stock compensation		8.6	%		—	%
Other		0.1	%		—	%
Total provision		3.0	%		(2.3	)%

Note 2 - Liquidity (Details Textual) $ in Millions	12 Months Ended
Note 2 - Liquidity (Details Textual) $ in Millions	Dec. 31, 2019 USD ($)
Proceeds from Issuance or Sale of Equity, Total	$ 16

Note 3 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Indefinite-lived Intangible Assets (Excluding Goodwill), Ending Balance	$ 8,639,000	$ 8,639,000
Operating Lease, Right-of-Use Asset	247,043
Operating Lease, Liability, Total	247,043
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			$ 300,000
Operating Lease, Liability, Total			$ 300,000
In-Process Research and Development Asset [Member]
Indefinite-lived Intangible Assets (Excluding Goodwill), Ending Balance	8,600,000	8,600,000
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0	$ 0
Minimum [Member]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	15 years

Note 3 - Basis of Presentation and Summary of Significant Accounting Policies - Fair Value on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Inputs, Level 1 [Member]
Cash equivalents	$ 14,006,193	$ 7,990,900
Fair Value, Inputs, Level 2 [Member]
Cash equivalents
Fair Value, Inputs, Level 3 [Member]
Cash equivalents

Note 3 - Basis of Presentation and Summary of Significant Accounting Policies - Outstanding Dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Anti-dilutive securities (in shares)	22,694,417	2,290,748
Warrant [Member]
Anti-dilutive securities (in shares)	22,385,141	2,087,012
Share-based Payment Arrangement, Option [Member]
Anti-dilutive securities (in shares)	309,276	203,736

Note 4 - Property and Equipment (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Depreciation, Total	$ 97,915	$ 110,371

Note 4 - Property and Equipment - Property and Equipment (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Property and equipment, gross	$ 763,799	$ 767,470
Less: accumulated depreciation	(511,433)	(417,189)
Property and equipment, net	252,366	350,281
Laboratory Equipment [Member]
Property and equipment, gross	182,357	182,357
Furniture and Fixtures [Member]
Property and equipment, gross	151,442	155,113
Leasehold Improvements [Member]
Property and equipment, gross	$ 430,000	$ 430,000

Note 5 - Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accrued payroll and payroll related expenses	$ 182,708	$ 409,889
Accrued professional fees	48,338	69,231
Accrued clinical studies expenses	57,378	34,000
Other	70,108	92,106
Total	$ 358,532	$ 605,226

Note 6 - Commitments and Contingencies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Operating Lease, Remaining Lease Term	2 years 109 days
Operating Lease, Liability, Current	$ 111,477		$ 100,000
Operating Lease, Liability, Noncurrent	135,566		$ 200,000
Lessee, Operating Lease, Discount Rate			10.00%
Lessee, Operating Lease, Renewal Term			5 years
Operating Lease, Expense	$ 100,000	100,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	90.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 68,000	$ 68,000

Note 6 - Commitments and Contingencies - Future Minimum Rental Payments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
2020	$ 116,464	$ 114,409
2021	118,519	116,464
2022	39,735	118,519
Total	274,718	389,127
Less: imputed interest	(27,675)
	$ 247,043
2022		$ 39,735

Note 7 - Stockholders' Equity and Common Stock Warrants (Details Textual) - USD ($)	1 Months Ended				12 Months Ended
	Dec. 31, 2019	Nov. 30, 2019	May 31, 2019	Jan. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Proceeds from Issuance or Sale of Equity, Total					$ 16,000,000
Proceeds from Warrant Exercises					3,888,425
Conversion of Stock, Shares Issued				1,400,462
Stock Issued During Period, Shares, Conversion of Convertible Securities				553,752
Common Stock Dividends, Shares				68,815
Stock Issued During Period, Shares, Make-whole Adjustment				777,895
Dividends, Make-whole Adjustment				$ 8,200,000		$ 8,167,895
Class of Warrant or Rights, Expired					1,767	28,123
Warrants Issued in Connection with the December 2019 Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	6,266,787				6,266,787
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.4335				$ 0.4335
Warrants Issued in Connection with the December 2019 Offering [Member] \| Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.6981				$ 0.6981
Placement Agent Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	313,339	571,429	65,853		313,339
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.6981	$ 0.4375	$ 6.11875		$ 0.6981
Warrants and Rights Outstanding, Term	5 years	5 years	5 years		5 years
Warrants Issued in Connection with the November 2019 Offering [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.35
Class of Warrant or Right, Issued During Period		6,324,143
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Class of Warrant or Right, Exercised During Period					11,091,716
Proceeds from Warrant Exercises					$ 3,900,000
Warrants Issued in Connection with the November 2019 Offering [Member] \| Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.4375				$ 0.4375
Warrants with 18 Months Term Issued in Connection with the November 2019 Offering [Member]
Warrants and Rights Outstanding, Term		1 year 180 days
Class of Warrant or Right, Issued During Period		11,428,572
Warrants with 5 Years Term Issued in Connection with the November 2019 Offering [Member]
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Issued During Period		11,428,572
Warrants Issued in Connection with the January 2018 Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 12
Warrants Issued in Connection with the January 2018 Offering [Member] \| Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 15				15
Option Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				150,000
Additional Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 12
Class of Warrant or Right, Granted				131,375
Underwriter Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 15
Class of Warrant or Right, Term				5 years
Underwriter Warrants [Member] \| Maximum [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				50,000
December 2019 Public Offering [Member]
Stock Issued During Period, Shares, New Issues	6,266,787
Shares Issued, Price Per Share	$ 0.5585				$ 0.5585
Proceeds from Issuance or Sale of Equity, Total	$ 3,000,000
November 2019 Public Offering [Member]
Stock Issued During Period, Shares, New Issues		5,104,429
Shares Issued, Price Per Share		$ 0.35
Proceeds from Issuance or Sale of Equity, Total		$ 3,300,000
Stock and Warrants Issued During Period, Number of Securities Called by Stock and Warrants		22,857,144
May 2019 Public Offering [Member]
Stock Issued During Period, Shares, New Issues			1,317,060
Shares Issued, Price Per Share			$ 4.895
Proceeds from Issuance or Sale of Equity, Total			$ 5,600,000
Warrants Issued in Connection with May 2019 Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,317,060
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 5
January 2018 Offering [Member]
Stock Issued During Period, Shares, New Issues				1,000,000
Proceeds from Issuance or Sale of Equity, Total				$ 10,800,000
Stock Issued During Period, Shares, Issued for Services				150,000

Note 7 - Stockholders' Equity and Common Stock Warrants - Warrants Outstanding to Acquire Shares of Its Common Stock (Details) - $ / shares	Dec. 31, 2019	Nov. 30, 2019	Jan. 31, 2018
Common stock warrants, outstanding (in shares)	22,385,141
Warrants Attached to Series A Convertible Preferred Stock [Member]
Common stock warrants, outstanding (in shares)	903,870
Range of exercise price (in dollars per share)	$ 33.30
Warrants Issued in Connection with the January 2018 Offering [Member]
Common stock warrants, outstanding (in shares)	1,181,375
Range of exercise price (in dollars per share)			$ 12
Warrants Issued in Connection with the January 2018 Offering [Member] \| Minimum [Member]
Range of exercise price (in dollars per share)	$ 12
Warrants Issued in Connection with the January 2018 Offering [Member] \| Maximum [Member]
Range of exercise price (in dollars per share)	$ 15
Warrants Issued in Connection with May 2019 Public Offering [Member]
Common stock warrants, outstanding (in shares)	1,382,913
Warrants Issued in Connection with May 2019 Public Offering [Member] \| Minimum [Member]
Range of exercise price (in dollars per share)	$ 5
Warrants Issued in Connection with May 2019 Public Offering [Member] \| Maximum [Member]
Range of exercise price (in dollars per share)	$ 6.11875
Warrants Issued in Connection with the November 2019 Offering [Member]
Common stock warrants, outstanding (in shares)	12,336,857
Range of exercise price (in dollars per share)		$ 0.35
Warrants Issued in Connection with the November 2019 Offering [Member] \| Minimum [Member]
Range of exercise price (in dollars per share)	$ 0.35
Warrants Issued in Connection with the November 2019 Offering [Member] \| Maximum [Member]
Range of exercise price (in dollars per share)	$ 0.4375
Warrants Issued in Connection with the December 2019 Offering [Member]
Common stock warrants, outstanding (in shares)	6,580,126
Range of exercise price (in dollars per share)	$ 0.4335
Warrants Issued in Connection with the December 2019 Offering [Member] \| Minimum [Member]
Range of exercise price (in dollars per share)	0.4335
Warrants Issued in Connection with the December 2019 Offering [Member] \| Maximum [Member]
Range of exercise price (in dollars per share)	$ 0.6981

Note 8 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 2.16	$ 12.63
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value		$ 0.6	$ 1.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		0	0
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		$ 0.3
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition		1 year 21 days
Equity Incentive Plan 2015 [Member]
Percentage of Total Shares Eligible for Plan Reserve, On an Annual Basis		4.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		19,740
Equity Incentive Plan 2015 [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,339,215

Note 8 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock-based compensation expense	$ 515,762	$ 1,221,591
Research and Development Expense [Member]
Stock-based compensation expense	54,155	62,161
General and Administrative Expense [Member]
Stock-based compensation expense	$ 461,607	$ 1,159,430

Note 8 - Stock-based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Options outstanding, number (in shares)	203,736	170,461
Options outstanding, weighted-average exercise price (in dollars per share)	$ 88.14	$ 109.74
Granted (in shares)	117,270	44,005
Granted, weighted-average exercise price (in dollars per share)	$ 2.62	$ 15.37
Forfeited (in shares)	(11,583)	(10,583)
Forfeited, weighted-average exercise price (in dollars per share)	$ 83.81	$ 131.25
Expired (in shares)	(147)	(147)
Expired, weighted-average exercise price (in dollars per share)	$ 276	$ 256.50
Options outstanding, weighted-average remaining contractual life (Year)	6 years 357 days	6 years 255 days
Options outstanding, aggregate intrinsic value		$ 143
Options outstanding, number (in shares)	309,276	203,736
Options outstanding, weighted-average exercise price (in dollars per share)	$ 55.78	$ 88.14
Options outstanding, weighted-average remaining contractual life (Year)	6 years 357 days	6 years 255 days
Exercisable (in shares)	235,415
Exercisable, weighted-average exercise price (in dollars per share)	$ 71.75
Exercisable, weighted-average remaining contractual life (Year)	6 years 124 days
Exercisable, aggregate intrinsic value
Vested and expected to vest (in shares)	309,276
Vested and expected to vest, weighted-average exercise price (in dollars per share)	$ 55.78
Vested and expected to vest, weighted-average remaining contractual life (Year)	6 years 357 days
Vested and expected to vest, aggregate intrinsic value

Note 8 - Stock-based Compensation - Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Minimum [Member]
Expected term (Year)	5 years 91 days	5 years 98 days
Risk-free interest rate	1.90%	2.30%
Expected volatility	112.40%	113.60%
Dividend yield
Maximum [Member]
Expected term (Year)	5 years 281 days	5 years 240 days
Risk-free interest rate	2.50%	2.80%
Expected volatility	114.40%	115.00%
Dividend yield

Note 9 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefits, Ending Balance	$ 0	$ 0
Open Tax Year	2016 2017 2018

Note 9 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Net operating loss carryforwards	$ 1,504,496	$ 5,875,074
Stock option compensation	1,381,750	2,456,410
Orphan Drug credits	81,700	2,847,803
Lease liability	63,589
Capitalized start-up costs and other	9,187,898	7,349,092
Valuation allowance	(12,051,440)	(18,091,090)
Deferred tax assets	167,993	437,289
Intangible assets	(2,223,678)	(2,223,678)
Right of use asset	(63,589)
Deferred tax liabilities	(2,287,267)	(2,223,678)
Net deferred tax liability	$ (2,119,274)	$ (1,786,389)

Note 9 - Income Taxes - Operating Loss Carryforwards (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Domestic Tax Authority [Member]
Operating loss carryforwards	$ 5,844,972	$ 22,819,972
State and Local Jurisdiction [Member]
Operating loss carryforwards	$ 5,844,972	$ 22,845,568

Note 9 - Income Taxes - Reconciliation of Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Federal tax benefit at statutory rate	(21.00%)	(21.00%)
State tax, net of Federal benefit	(2.50%)	(2.90%)
Goodwill impairment		7.70%
Orphan drug credit	25.30%	(1.30%)
Change in valuation allowance	(7.50%)	15.20%
Stock compensation	8.60%
Other	0.10%
Total provision	3.00%	(2.30%)

Note 11 - Subsequent Event (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
Note 11 - Subsequent Event (Details Textual) - USD ($)	Mar. 17, 2020	Dec. 31, 2019	Dec. 31, 2018
Proceeds from Warrant Exercises		$ 3,888,425
Subsequent Event [Member]
Class of Warrant or Right, Exercised	1,124,071
Class of Warrant or Right, Exercised During Period, Exercise Price	$ 0.35
Proceeds from Warrant Exercises	$ 400,000