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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Mar. 24, 2020	Jun. 30, 2019
Document And Entity Information
Entity Registrant Name	Celsion CORP
Entity Central Index Key	0000749647
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 38,200,000
Entity Common Stock, Shares Outstanding		29,257,101
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 6,875,273	$ 13,353,543
Investment in debt securities - available for sale, at fair value	7,985,886	14,257,998
Accrued interest receivable on investment securities	21,369	68,309
Advances and deposits on clinical programs and other current assets	1,352,670	451,293
Total current assets	16,235,198	28,131,143
Property and equipment (at cost, less accumulated depreciation and amortization)	405,363	184,627
Other assets:
Deferred income tax asset	1,819,324
In-process research and development, net	15,736,491	15,736,491
Goodwill	1,976,101	1,976,101
Operating lease right-of-use assets, net	1,431,640
Other intangible assets, net	340,976	568,292
Deposits and other assets	333,274	258,933
Total other assets	21,637,806	18,539,817
Total assets	38,278,367	46,855,587
Current liabilities:
Accounts payable - trade	2,862,949	3,020,638
Other accrued liabilities	2,303,547	2,585,898
Notes payable - current portion, net of deferred financing costs	1,840,228
Operating lease liability - current portion	387,733
Deferred revenue - current portion	500,000	500,000
Total current liabilities	7,894,457	6,106,536
Earn-out milestone liability	5,717,709	8,907,664
Note Payable, net of deferred financing costs	7,963,449	9,417,037
Operating lease liability - non-current portion	1,143,717
Deferred revenue - non-current portion	1,000,000	1,500,000
Other liabilities - non-current		63,278
Total liabilities	23,719,332	25,994,515
Commitments and contingencies
Stockholders' equity:
Preferred Stock - $0.01 par value (100,000 shares authorized, and no shares issued or outstanding at December 31, 2019 and 2018)
Common stock - $0.01 par value (112,500,000 shares authorized; 23,256,152 and 18,832,168 shares issued at December 31, 2019 and 2018, respectively, and 23,255,818 and 18,831,834 shares outstanding at December 31, 2019 and 2018, respectively)	232,562	188,322
Additional paid-in capital	304,885,663	294,393,313
Accumulated other comprehensive gain	42,778	29,872
Accumulated deficit	(290,516,780)	(273,665,247)
Total stockholders' equity before treasury stock	14,644,223	20,946,260
Treasury stock, at cost (334 shares at December 31, 2019 and 2018)	(85,188)	(85,188)
Total stockholders' equity	14,559,035	20,861,072
Total liabilities and stockholders' equity	$ 38,278,367	$ 46,855,587

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	112,500,000	112,500,000
Common stock, shares issued	23,256,152	18,832,168
Common stock, shares outstanding	23,255,818	18,831,834
Treasury stock, shares	334	334

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Technology development and licensing revenue	$ 500,000	$ 500,000
Operating expenses:
Research and development	13,065,309	11,865,523
General and administrative	8,000,164	9,699,521
Total operating expenses	21,065,473	21,565,044
Loss from operations	(20,565,473)	(21,065,044)
Other income (expense):
Gain from change in earn-out milestone liability	3,189,955	3,630,861
Fair value of warrants issued in connection with amendment to modify GEN-1 earn-out milestone payments	(400,000)
Impairment of in-process research and development		(4,510,000)
Investment income, net	500,882	353,682
Interest expense	(1,393,400)	(712,025)
Other income	29	52
Total other income (expense)	1,897,466	(1,237,430)
Net loss before income tax benefit	(18,668,007)	(22,302,474)
Income tax benefit	1,816,474	10,419,115
Net loss	$ (16,851,533)	$ (11,883,359)
Net loss per common share - basic and diluted	$ (0.77)	$ (0.68)
Weighted average common shares outstanding - basic and diluted	21,832,932	17,582,879

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
Consolidated Statements of Comprehensive Loss - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (16,851,533)	$ (11,883,359)
Changes in:
Realized (gain) loss on investment securities recognized in investment income, net	(57,895)	10,164
Unrealized gain (loss) on investment securities	70,801	29,872
Other comprehensive income (loss)	12,906	40,036
Comprehensive loss	$ (16,838,627)	$ (11,843,323)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (16,851,533)	$ (11,883,359)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization	721,665	356,859
Change in fair value of earn-out milestone liability	(3,189,955)	(3,630,861)
Fair value of warrants issued in connection with amendment to modify the GEN-1 earn-out milestone payments	400,000
Stock-based compensation	2,286,388	4,604,415
Shares issues in upon vesting of stock awards	5,350
Deferred income tax asset	(1,819,324)
Shares issued in exchange for services		29,841
Impairment of in-process research and development		4,510,000
Amortization of deferred finance charges and debt discount associated with note payable	386,640	199,153
Change in deferred rent liability		(8,432)
Net changes in:
Interest receivable on investments	46,940	(13,869)
Advances and deposits on clinical programs and other current assets	(901,377)	(362,107)
Other assets	(74,341)	(250,172)
Accounts payable - trade	(157,689)	(396,225)
Deferred revenue	(500,000)	(500,000)
Other accrued liabilities	(611,746)	303,071
Net cash used in operating activities	(20,258,982)	(7,041,686)
Cash flows from investing activities:
Purchases of investment in debt securities	(23,829,982)	(16,973,942)
Proceeds from sale and maturity of investment in debt securities	30,115,000	15,480,000
Purchases of property and equipment	(349,158)	(138,399)
Net cash provided by (used in) investing activities	5,935,860	(1,632,341)
Cash flows from financing activities:
Proceeds from issuance of common stock equity, net of issuance costs	7,844,852	858,515
Proceeds from note payable, net of issuance costs		9,725,000
Net cash provided by financing activities	7,844,852	10,583,515
(Decrease) Increase in cash and cash equivalents	(6,478,270)	1,909,488
Cash and cash equivalents at beginning of period	13,353,543	11,444,055
Cash and cash equivalents at end of period	6,875,273	13,353,543
Cash (paid for) received from:
Interest	(760,615)	(512,872)
Income tax benefit		10,419,115
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows from lease payments	485,848
Non-cash financing and investing activities
Fair value of warrants issued in connection with amendment to modify the GEN-1 earn-out milestone payments	400,000
Fair value of common stock issued as equity issuance costs and charged against paid in capital		450,000
Fair value of warrants issued in connection with the debt facility		507,116
Fair value of stock issued in exchange for cancelation of warrants		8,207
Right of use assets obtained in exchange for lease liabilities
Operating leases	1,797,561
Realized and unrealized gains and losses, net, on investment in debt securities	$ 12,906	$ 40,036

Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2017	$ 172,772	$ 288,408,976	$ (85,188)	$ (10,164)	$ (261,781,888)	$ 26,704,508
Balance, shares at Dec. 31, 2017	17,276,965		334
Net loss					(11,883,359)	(11,883,359)
Sale of equity through ATM and common stock purchase agreement	$ 5,572	983,528				989,100
Sale of equity through ATM and common stock purchase agreement, shares	557,070
Common stock issuance in exchange for cancellation of common stock warrants	$ 8,207	(138,792)				(130,585)
Common stock issuance in exchange for cancellation of common stock warrants, shares	820,714
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities	$ 1,648	505,468				507,116
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities, shares	164,835
Realized and unrealized gains and losses, net, on investments securities				40,036		40,036
Stock-based compensation expense		4,604,415				4,604,415
Issuance of restricted stock	$ 123	29,718				29,841
Issuance of restricted stock, shares	12,250
Balance at Dec. 31, 2018	$ 188,322	294,393,313	$ (85,188)	29,872	(273,665,247)	20,861,072
Balance, shares at Dec. 31, 2018	18,831,834		334
Net loss					(16,851,533)	(16,851,533)
Realized and unrealized gains and losses, net, on investments securities				12,906		12,906
Stock-based compensation expense		2,286,388				2,286,388
Issuance of restricted stock	$ 380	4,970				5,350
Issuance of restricted stock, shares	38,000
Sale of equity through equity financing facilities	$ 43,860	7,800,992				7,844,852
Sale of equity through equity financing facilities, shares	4,385,984
Common stock warrants issued in connection with amendment to modify GEN-1 earn-out milestone payments		400,000				400,000
Balance at Dec. 31, 2019	$ 232,562	$ 304,885,663	$ (85,188)	$ 42,778	$ (290,516,780)	$ 14,559,035
Balance, shares at Dec. 31, 2019	23,255,818		334

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Description of Business

Celsion Corporation (“Celsion” and the “Company”) is an integrated development clinical stage oncology drug company focused on advancing innovative cancer treatments, including directed chemotherapies, DNA-mediated immunotherapy and RNA-based therapies. Our lead product candidate is ThermoDox®, a proprietary heat-activated liposomal encapsulation of doxorubicin, currently in a Phase III clinical trial for the treatment of primary liver cancer (the “OPTIMA Study”). Second in our product pipeline is GEN-1, a DNA-mediated immunotherapy for the localized treatment of ovarian cancer. These investigational products are based on platform technologies that provide the basis for future development of a range of therapeutics, largely focused on difficult-to-treat forms of cancer. The first platform technology is Lysolipid Thermally Sensitive Liposomes, a heat sensitive liposomal based dosage form that is designed to target disease with known chemotherapeutics in the presence of mild heat. The second platform technology is TheraPlas, a novel nucleic acid-based investigational candidate under development for local transfection of therapeutic DNA plasmids. Employing these technologies, we are working to develop and commercialize more efficient, effective and targeted oncology therapies that maximize efficacy while minimizing side effects common to cancer treatments.

Basis of Presentation

The accompanying consolidated financial statements of Celsion have been prepared in accordance with generally accepted accounting principles (“GAAP”) in the United States and include the accounts of the Company and CLSN Laboratories, Inc. All significant intercompany balances and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make judgments, estimates, and assumptions that affect the amount reported in the Company’s financial statements and accompanying notes. Actual results could differ materially from these estimates.

Events and conditions arising subsequent to the most recent balance sheet date through the date of the issuance of these consolidated financial statements have been evaluated for their possible impact on the financial statements and accompanying notes. No events and conditions would give rise to any information that required accounting recognition or disclosure in the financial statements other than those arising in the ordinary course of business.

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, the fair value of the earn-out milestone liabilities, estimates for contingent liabilities, if any, and accounting for valuation of in-process research and development assets. Management believes its estimates to be reasonable under the circumstances. Actual results could differ significantly from those estimates. Significant estimates in these financials are the valuation of options granted and valuation methods used to determine the recoverability of goodwill and other intangible assets.

Revenue Recognition

On January 1, 2018, the Company adopted the new accounting standard ASC 606, Revenue from Contracts with Customers and all related amendments (the “new revenue standard”) to all contracts with customers using the modified retrospective method. The adoption of the new revenue standard had no impact on retained earnings as of December 31, 2017 and, accordingly, no cumulative adjustment was required. We do not expect the new revenue standard to have a significant impact on our net income on an ongoing basis. The Company’s sole revenue stream is related to the Hisun agreement described in Note 16. There were no accounts receivable as of December 31, 2019 or 2018. Contract liabilities from the Hisun agreement amounted to $1,500,000, $2,000,000 and $2,500,000 at December 31, 2019, 2018and 2017, respectively. Contract liabilities values represent the value of cash received before the services were provided.

Cash and Cash Equivalents

Cash and cash equivalents include cash on hand and investments purchased with an original maturity of three months or less. A portion of these funds are not covered by FDIC insurance.

Fair Value of Investment in Debt Securities

The carrying values of investment securities approximate their respective fair values.

Short Term Investments

The Company classifies its investments in debt securities with readily determinable fair values as investments available-for-sale in accordance with Accounting Standards Codification (ASC) 320, Investments - Debt and Equity Securities. Available-for-sale securities consist of debt securities not classified as trading securities or as securities to be held to maturity. The Company has classified all of its investments as available-for-sale. Unrealized holding gains and losses on available-for-sale securities are reported as a net amount in accumulated other comprehensive gain or loss in stockholders’ equity until realized. Gains and losses on the sale of available-for-sale securities are determined using the specific identification method. The Company’s short-term investments consist of corporate bonds.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is provided over the estimated useful lives of the related assets, ranging from three to seven years, using the straight-line method. Amortization is recognized over the lesser of the life of the asset or the lease term. Major renewals and improvements are capitalized at cost and ordinary repairs and maintenance are charged against operating expenses as incurred. Depreciation expense was approximately $128,500 and $130,000 for the years ended December 31, 2019 and 2018, respectively.

The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An asset is considered impaired if its carrying amount exceeds the future net undiscounted cash flows that the asset is expected to generate. If such asset is considered to be impaired, the impairment recognized is the amount by which the carrying amount of the asset, if any, exceeds its fair value determined using a discounted cash flow model.

Deposits

Deposits include real property security deposits and other deposits which are contractually required and of a long-term nature.

In-Process Research and Development, Other Intangible Assets and Goodwill

During 2014, the Company acquired certain assets of EGEN, Inc. As more fully described in Note 5, the acquisition was accounted for under the acquisition method of accounting which required the Company to perform an allocation of the purchase price to the assets acquired and liabilities assumed. Under the acquisition method of accounting, the total purchase price is allocated to net tangible and intangible assets and liabilities based on their estimated fair values as of the acquisition date.

Impairment or Disposal of Long-Lived Assets

The Company assesses the impairment of its long-lived assets under accounting standards for the impairment or disposal of long-lived assets whenever events or changes in circumstances indicate that the carrying value may not be recoverable. For long-lived assets to be held and used, the Company recognizes an impairment loss only if its carrying amount is not recoverable through its undiscounted cash flows and measures the impairment loss based on the difference between the carrying amount and fair value.

Comprehensive Income (Loss)

Accounting Standards Codification (“ASC”) 220, Comprehensive Income, establishes standards for the reporting and display of comprehensive income (loss) and its components in the Company’s consolidated financial statements. The objective of ASC 220 is to report a measure comprehensive income (loss) of all changes in equity of an enterprise that result from transactions and other economic events in a period other than transactions with owners. Comprehensive gains (losses) result from changes in unrealized gains and losses from investment in debt securities.

Research and Development

Research and development costs are expensed as incurred. Equipment and facilities acquired for research and development activities that have alternative future uses are capitalized and charged to expense over their estimated useful lives.

Net Loss Per Common Share

Basic and diluted net loss per common share was computed by dividing net loss for the year by the weighted average number of shares of common stock outstanding, both basic and diluted, during each period. The impact of common stock equivalents has been excluded from the computation of diluted weighted average common shares outstanding in periods where there is a net loss, as their effect is anti-dilutive.

For the years ended December 31, 2019 and 2018, the total number of shares of common stock issuable upon exercise of warrants and equity awards is 4,766,990 and 4,764,405 respectively. Warrants with an exercise price of $0.01 (as more fully described in Note 13 of these financial statements) exercisable for 200,000 shares of common stock were considered issued in calculating basic loss per share. For the year ended December 31, 2019 and 2018, diluted loss per common share is the same as basic loss per common share as all options and all other warrants that were convertible into shares of the Company’s common stock were excluded from the calculation of diluted earnings attributable to common stockholders per common share as their effect would be anti-dilutive.

Income Taxes

Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the 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 tax credit carry forwards. 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. The effect on deferred tax asset and liabilities of a change in tax rates is recognized in results of operations in the period that the tax rate change occurs. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. In accordance with ASC 740, Income Taxes, a tax position is recognized as a benefit only if it is “more likely than not” that the tax position taken would be sustained in a tax examination, presuming that a tax examination will occur. The Company recognizes interest and/or penalties related to income tax matters in the income tax expense category.

As more fully discussed in Note 9, the Company received approval from the New Jersey Economic Development Authority to sell $1.9 million of its New Jersey net operating losses recognizing a tax benefit for the year ended December 31, 2019 for the net proceeds (approximately $1.8 million) by reducing the deferred income tax valuation allowance. In early 2020, the Company entered into an agreement to sell these net operating losses and expects to receive net proceeds of approximately $1.8 million in the second quarter of 2020. In 2018, the Company completed the sale of a portion of its New Jersey net operating losses for 2011 - 2017 totaling approximately $11.1 for net proceeds of approximately $10.4 million in December 2018. The proceeds of $10.4 million were reflected as a tax benefit for the year ended December 31, 2018.

Stock-Based Compensation

In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation, which simplifies various aspects of accounting for share-based payments. The areas for simplification involve several aspects of the accounting for share-based payment transactions, including the income tax consequences and classification on the statements of cash flows. The Company recognizes the effect of forfeitures in compensation cost when they occur.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) and are adopted by us as of the specified effective date. Unless otherwise discussed, we believe that the impact of recently issued accounting pronouncements will not have a material impact on the Company’s consolidated financial position, results of operations, and cash flows, or do not apply to our operations.

In February 2016, the FASB issued Accounting Standards Update No. 2016-02, “Leases” - Topic 842 (ASC Topic 842), which requires that lessees recognize assets and liabilities for leases with lease terms greater than twelve months in the statement of financial position. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. This update also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update became effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that reporting period. The FASB subsequently issued the following amendments to ASC Topic 842, which have the same effective date and transition date of January 1, 2019:

●	ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which amends certain narrow aspects of the guidance issued in ASU 2016-02; and

●	ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component.

We adopted Topic ASC 842 effective January 1, 2019 and elected to apply the available practical expedients and implement internal controls to enable the preparation of financial information on adoption. We identified two of our leases consisting of the New Jersey corporate office lease and the Alabama lab facility lease as being subject to Topic ASC 842. The adoption of this standard resulted in the recognition of right-of-use assets of approximately $1.4 million, related operating lease liabilities of $1.5 million and reduced other liabilities by approximately $0.1 million on the consolidated balance sheets as of January 1, 2019 with no material impact to the opening balance of retained earnings. See Note 15 for further discussions regarding the adoption of ASC Topic 842.

In June 2016, the FASB issued Accounting Standard Update No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments”, which modifies the measurement of expected credit losses on certain financial instruments. The Company expects to adopt ASU 2016-13 in its first quarter of 2021 utilizing the modified retrospective transition method. Based on the composition of the Company’s investment portfolio and current market conditions, the adoption of ASU 2016-13 is not expected to have a material impact on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which adds and modifies certain disclosure requirements for fair value measurements. Under the new guidance, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, or valuation processes for Level 3 fair value measurements. However, public companies will be required to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and related changes in unrealized gains and losses included in other comprehensive income. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods, and early adoption is permitted. The Company is in the process of determining the impact the adoption will have on its financial statements.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740). The standard simplifies the accounting for incomes taxes by removing certain exceptions to the general principles in Topic 740 related to the approach for intraperiod tax allocation and the recognition of deferred tax liabilities for outside basis differences. The standard also clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. The standard also improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The amendment is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of this standard will have on its consolidated financial statements.

Financial Condition

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Financial Condition

2. FINANCIAL CONDITION

Since inception, the Company has incurred substantial operating losses, principally from expenses associated with the Company’s research and development programs, clinical trials conducted in connection with the Company’s product candidates, and applications and submissions to the U.S. Food and Drug Administration. We have not generated significant revenue and have incurred significant net losses in each year since our inception. We have incurred approximately $291 million of cumulated net losses. As of December 31, 2019, we had approximately $16.7 million in cash, investment securities, interest receivable and deferred income tax asset. We have substantial future capital requirements to continue our research and development activities and advance our product candidates through various development stages. The Company believes these expenditures are essential for the commercialization of its technologies.

The Company expects its operating losses to continue for the foreseeable future as it continues its product development efforts, and when it undertakes marketing and sales activities. The Company’s ability to achieve profitability is dependent upon its ability to obtain governmental approvals, manufacture, and market and sell its new product candidates. There can be no assurance that the Company will be able to commercialize its technology successfully or that profitability will ever be achieved. The operating results of the Company have fluctuated significantly in the past. We have substantial future capital requirements associated with our continued research and development activities and to advance our product candidates through various stages of development. The Company believes these expenditures are essential for the commercialization of its technologies. In January 2020, the World Health Organization (WHO) declared an outbreak of coronavirus, COVID-19, to be a “Public Health Emergency of International Concern,” and the U.S. Department of Health and Human Services declared a public health emergency to aid the U.S. healthcare community in responding to COVID-19. This virus continues to spread globally and, as of late March 2020, has spread to over 100 countries, including the United States. Our ability to raise additional capital may be adversely impacted by potential worsening global economic conditions and the recent disruptions to, and volatility in, financial markets in the United States and worldwide resulting from the ongoing COVID-19 pandemic.

The disruptions caused by COVID-19 may also disrupt the clinical trials process and enrollment of patients. This may delay commercialization efforts. The Company is currently monitoring its operating activities in light of these events and it is reasonably possible that the virus could have a negative effect on the Company’s financial condition and results of operations, the specific impact is not readily determinable as of the date of these financial statements.

The actual amount of funds the Company will need to operate is subject to many factors, some of which are beyond the Company’s control. These factors include the following:

	●	the progress of research activities;

	●	the number and scope of research programs;

	●	the progress of preclinical and clinical development activities;

	●	the progress of the development efforts of parties with whom the Company has entered into research and development agreements;

	●	the costs associated with additional clinical trials of product candidates;

	●	the ability to maintain current research and development licensing arrangements and to establish new research and development and licensing arrangements;

	●	the ability to achieve milestones under licensing arrangements;

	●	the costs involved in prosecuting and enforcing patent claims and other intellectual property rights; and

	●	the costs and timing of regulatory approvals.

The Company has based its estimate on assumptions that may prove to be wrong. The Company may need to obtain additional funds sooner or in greater amounts than it currently anticipates. Potential sources of financing include strategic relationships, public or private sales of the Company’s shares or debt, the additional sales from the sale of its State of New Jersey net operating losses in the future and other sources. If the Company raises funds by selling additional shares of common stock or other securities convertible into common stock, the ownership interest of existing stockholders may be diluted.

During 2019 and 2018, the Company submitted an application to sell a portion of the Company’s New Jersey NOLs as part of the Technology Business Tax Certificate Program sponsored by The New Jersey Economic Development Authority. Under the program, emerging biotechnology companies with unused NOLs and unused research and development credits are allowed to sell these benefits to other companies. As more fully discussed in Note 9, the Company received approval from the New Jersey Economic Development Authority to sell $1.9 million of its New Jersey net operating losses recognizing a tax benefit for the year ended December 31, 2019 for the net proceeds (approximately $1.8 million) by reducing the deferred income tax valuation allowance. In early 2020, the Company entered into an agreement to sell these net operating losses and expects to receive net proceeds of approximately $1.8 million in the second quarter of 2020. In 2018, the Company completed the sale of a portion of its New Jersey net operating losses for 2011 - 2017 totaling approximately $11.1 for net proceeds of approximately $10.4 million in December 2018. The proceeds of $10.4 million were reflected as a tax benefit for the year ended December 31, 2018. The Company has approximately $2.1 million in future tax benefits remaining under the NOL Program for future years.

With $16.7 million in cash, investment securities, interest receivable and deferred income tax asset at December 31, 2019, as well as the $6.4 million raised in equity financings so far in 2020 (Note 10), the Company believes it has sufficient capital resources to fund its operations and financial commitments thru mid-2021. The Company will be required to obtain additional funding to continue development of its current product candidates within the anticipated time periods, if at all, and to continue to fund operations. As more fully discussed in Note 10, the Company has approximately $15 million available for future sale of equity securities under the common stock sales agreement with JonesTrading International Services LLC.

Investments in Debt Securities Available For Sale

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Investments in Debt Securities Available For Sale

3. INVESTMENTS IN DEBT SECURITIES AVAILABLE FOR SALE

Investments in debt securities available for sale of $7,985,886 and $14,257,998 as of December 31, 2019 and 2018, respectively, consist of corporate debt securities. These investments are valued at estimated fair value, with unrealized gains and losses reported as a separate component of stockholders’ equity in accumulated other comprehensive loss.

Investments in debt securities available for sale are evaluated periodically to determine whether a decline in their value is other than temporary. The term “other than temporary” is not intended to indicate a permanent decline in value. Rather, it means that the prospects for near term recovery of value are not necessarily favorable, or that there is a lack of evidence to support fair values equal to, or greater than, the carrying value of the security. Management reviews criteria such as the magnitude and duration of the decline, as well as the reasons for the decline, to predict whether the loss in value is other than temporary. Once a decline in value is determined to be other than temporary, the value of the security is reduced and a corresponding charge to earnings is recognized.

A summary of the cost, fair value and maturities of the Company’s short-term investments is as follows:

	December 31, 2019				December 31, 2018
	Cost		Fair Value		Cost		Fair Value
Short-term investments
Corporate debt securities	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998
Total	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998

	December 31, 2019				December 31, 2018
	Cost		Fair Value		Cost		Fair Value
Short-term investment maturities
Within 3 months	$	7,943,108	$	7,985,886	$	5,383,488	$	5,393,743
Between 3-12 months		-		-		8,844,638		8,864,255
Total	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998

The following table shows the Company’s investment in debt securities available for sale gross unrealized gains (losses) and fair value by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31, 2019 and 2018. The Company has reviewed individual securities to determine whether a decline in fair value below the amortizable cost basis is other than temporary.

	December 31, 2019				December 31, 2018
Available for sale securities (all unrealized holding gains and losses are less than 12 months at date of measurement)	Fair Value		Unrealized Holding Gains (Losses)		Fair Value		Unrealized Holding Gains (Losses)

Investments in debt securities with unrealized gains	$	7,985,886	$	42,778	$	7,515,676	$	38,068
Investments in debt securities with unrealized losses		-		-		6,742,322		(8,196	)
Total	$	7,985,886	$	42,778	$	14,257,998	$	29,872

Investment income, which includes net realized losses on sales of available for sale securities and investment income interest and dividends, is summarized as follows:

	2019		2018
Interest and dividends accrued and paid	$	442,987	$	363,846
Realized gains (losses)		57,895		(10,164	)
Investment income net	$	500,882	$	353,682

Fair Values of Financial Instruments

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Values of Financial Instruments

4. FAIR VALUES OF FINANCIAL INSTRUMENTS

FASB Accounting Standards Codification (ASC) Section 820 “Fair Value Measurements and Disclosures,” establishes a three-level hierarchy for fair value measurements which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The three levels of inputs that may be used to measure fair value are as follows:

Level 1: Quoted prices (unadjusted) or identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date;

Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data; and

Level 3: Significant unobservable inputs that reflect a reporting entity’s own assumptions that market participants would use in pricing an asset or liability.

Cash and cash equivalents, other current assets, accounts payable and other accrued liabilities are reflected in the condensed consolidated balance sheet at their approximate estimated fair values primarily due to their short-term nature. The fair values of securities available for sale is determined by relying on the securities’ relationship to other benchmark quoted securities and classified its investments as Level 2 items in both 2019 and 2018. There were no transfers of assets or liabilities between Level 1 and Level 2 and no transfers in or out of Level 3 during the year ended December 31, 2019 or 2018. The changes in Level 3 liabilities were the result of changes in the fair value of the earn-out milestone liability included in earnings and in-process R&D. The earnout milestone liability is valued using a risk-adjusted assessment of the probability of payment of each milestone, discounted to present value using an estimated time to achieve the milestone (see Note 12). The in-process R&D – GBM is valued using a multi-period excess earnings method (see note 5).

Assets and liabilities measured at fair value are summarized below:

	Total Fair Value		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:

Recurring items as of December 31, 2019
Corporate debt securities, available for sale	$	7,985,886	$	─	$	7,985,886	$	─

Recurring items as of December 31, 2018
Corporate debt securities, available for sale	$	14,257,998	$	─	$	14,257,998	$	─

Liabilities:

Recurring items as of December 31, 2019
Earn-out milestone liability (Note 13)	$	5,717,709	$	─	$	─	$	5,717,709

Recurring items as of December 31, 2018
Earn-out milestone liability (Note 13)	$	8,907,664	$	─	$	─	$	8,907,664

Intangible Assets

12 Months Ended

Dec. 31, 2019

Intangible Assets, Net (Including Goodwill) [Abstract]

Intangible Assets

5. INTANGIBLE ASSETS.

In June 2014, we completed the acquisition of substantially all of the assets of EGEN, Inc., an Alabama corporation, which has changed its company name to EGWU, Inc. after the closing of the acquisition (“EGEN”). We acquired all of EGEN’s right, title and interest in and to substantially all of the assets of EGEN, including cash and cash equivalents, patents, trademarks and other intellectual property rights, clinical data, certain contracts, licenses and permits, equipment, furniture, office equipment, furnishings, supplies and other tangible personal property. In addition, CLSN Laboratories assumed certain specified liabilities of EGEN, including the liabilities arising out of the acquired contracts and other assets relating to periods after the closing date.

Acquired In-process Research and Development

Acquired in-process research and development (IPR&D) consists of EGEN’s drug technology platforms: TheraPlas and TheraSilence. The fair value of the IPR&D drug technology platforms was estimated to be $24.2 million as of the acquisition date. As of the closing of the acquisition, the IPR&D was considered indefinite lived intangible assets and will not be amortized. IPR&D is reviewed for impairment at least annually as of our third quarter ended September 30, and whenever events or changes in circumstances indicate that the carrying value of the assets might not be recoverable. On December 31, 2016, the Company determined one of its IPR&D assets related to its RNA delivery system was impaired and wrote off its fair value, incurring a non-cash charge of $1.4 million during 2016. During its annual assessments on September 30, 2017 and 2018, the Company determined its IPR&D asset related to its glioblastoma multiforme cancer (GBM) product candidate, originally fair valued at $9.4 million on the date of acquisition, was impaired and wrote this asset’s carrying value down to $2.4 million collectively after those two assessments, incurring non-cash charges of $2.5 million and $4.5 million during 2017 and 2018, respectively. On September 30, 2019, the Company evaluated its IPR&D of the (GBM) product candidate and concluded that it is not more likely than not that the asset is further impaired. As no other indicators of impairment existed during the fourth quarter of 2019, the Company concluded none of the other IPR&D assets were impaired at December 31, 2019. The carrying amount of the GBM) product candidate indication was $2.4 million at December 31, 2019 and 2018.

At September 30, 2019 and 2018, the Company evaluated its IPR&D of the ovarian cancer indication and concluded that it is not more likely than not that the asset is impaired. As no other indicators of impairment existed during the fourth quarter of 2019, the Company concluded none of the other IPR&D assets were impaired at December 31, 2019. The carrying amount of the ovarian cancer indication was $13.3 million at December 31, 2019 and 2018.

Covenants Not to Compete

Pursuant to the EGEN Purchase Agreement, EGEN provided certain covenants (“Covenant Not To Compete”) to the Company whereby EGEN agreed, during the period ending on the seventh anniversary of the closing date of the acquisition on June 20, 2014, not to enter into any business, directly or indirectly, which competes with the business of the Company nor will it contact, solicit or approach any of the employees of the Company for purposes of offering employment. The Covenant Not to Compete which was valued at approximately $1.6 million at the date of the EGEN acquisition has a definitive life and is amortized on a straight-line basis over its life of 7 years. The Company recognized amortization expense of $227,316 in 2019 and 2018. The carrying value of the Covenant Not to Compete was $340,976, net of $1,250,238 accumulated amortization, as of December 31, 2019 and $568,292, net of $1,022,922 accumulated amortization as of December 31, 2018

Following is a schedule of future amortization amounts during the remaining life of the Covenant Not to Compete.

	Year Ended December 31,
2020	$	227,316
2021		113,660
Total	$	340,976

Goodwill

The purchase price exceeded the estimated fair value of the net assets acquired by approximately $2.0 million which was recorded as Goodwill. Goodwill represents the difference between the total purchase price for the net assets purchased from EGEN and the aggregate fair values of tangible and intangible assets acquired, less liabilities assumed. Goodwill is reviewed for impairment at least annually as of our third quarter ended September 30 or sooner if we believe indicators of impairment exist. As of September 30, 2019, we concluded that the Company’s fair value exceeded its carrying value therefore “it is not more likely than not” that the Goodwill was impaired. As no other indicators of impairment existed during the fourth quarter of 2019, the Company concluded it is “not more likely than not” Goodwill was impaired.

Following is a summary of the net fair value of the assets acquired in the EGEN acquisition for the two years ended December 31, 2019:

	IPR&D			Goodwill		Covenant Not to Compete

Balance at January 1, 2018, net	$	20,246,491		$	1,976,101	$	795,608
Amortization		-			-		(227,316	)
Impairment charge		(4,510,000	)		-		-
Balance at December 31, 2018, net		15,736,491			1,976,101		568,292
Amortization		-			-		(227,316	)
Balance at December 31, 2019, net	$	15,736,491		$	1,976,101	$	340,976

Property and Equipment

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property and Equipment

6. PROPERTY AND EQUIPMENT

	Year Ended December 31,
	2019			2018
Machinery and equipment (5-7 year life)	$	2,831,564		$	2,596,170
Furniture and fixtures (3-5 year life)		327,278			267,712
Leasehold improvements (5-7 year life)		343,202			289,004
		3,502,044			3,152,886
Less accumulated depreciation and amortization		(3,096,681	)		(2,968,259	)
Total	$	405,363		$	184,627

Other Accrued Liabilities

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Other Accrued Liabilities

7. OTHER ACCRUED LIABILITIES

Other accrued liabilities at December 31, 2019 and 2018 include the following:

	Year Ended December 31,
	2019		2018
Amounts due to contract research organizations and other contractual agreements	$	475,440	$	749,369
Accrued payroll and related benefits		1,604,541		1,592,590
Accrued professional fees		204,155		198,654
Other		19,411		45,285
Total	$	2,303,547	$	2,585,898

Notes Payable

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Notes Payable

8. NOTES PAYABLE

Horizon Credit Agreement

On June 27, 2018, the Company entered into a loan agreement with Horizon Technology Finance Corporation (“Horizon”) that provided $10 million in new capital (the “Horizon Credit Agreement”). The Company drew down $10 million upon closing of the Horizon Credit Agreement on June 27, 2018. The Company will use the funding provided under the Horizon Credit Agreement for working capital and advancement of its product pipeline.

The obligations under the Horizon Credit Agreement are secured by a first-priority security interest in substantially all assets of Celsion other than intellectual property assets. The obligations will bear interest at a rate calculated based on one-month LIBOR plus 7.625%. The effective interest rate at December 31, 2019 was 9.63%. Payments under the loan agreement are interest only for the first twenty-four (24) months after loan closing, followed by a 24-month amortization period of principal and interest through the scheduled maturity date. At its option, the Company can prepay all of the outstanding principal balance by prepaying the outstanding principal balance and an amount equal to 1-3% of the outstanding principal balance at that time, based on the amount of time prior to the maturity date of the notes.

The Horizon Credit Agreement contains customary representations, warranties and affirmative and negative covenants including, among other things, covenants that limit or restrict Celsion’s ability to grant liens, incur indebtedness, make certain restricted payments, merge or consolidate and make dispositions of assets. Upon the occurrence of an event of default under the Horizon Credit Agreement, the lenders may cease making loans, terminate the Horizon Credit Agreement, declare all amounts outstanding to be immediately due and payable and foreclose on or liquidate Celsion’s assets that comprise the lenders’ collateral. The Horizon Credit Agreement specifies a number of events of default (some of which are subject to applicable grace or cure periods), including, among other things, non-payment defaults, covenant defaults, a material adverse effect on Celsion or its assets, cross-defaults to other material indebtedness, bankruptcy and insolvency defaults and material judgment defaults.

As a fee in connection with the Horizon Credit Agreement, Celsion issued Horizon warrants exercisable for a total of 190,114 shares of Celsion’s common stock (the “Horizon Warrants”) at a per share exercise price of $2.63. The Horizon Warrants are immediately exercisable for cash or by net exercise from the date of grant and will expire after ten years from the date of grant. Celsion registered the Horizon Warrants on Form S-3 (File No. 333 - 227236) filed with the Securities and Exchange Commission on September 7, 2018 and declared effective on October 10, 2018. The Company valued the Horizon Warrants issued using the Black-Scholes option pricing model and recorded a total of $507,116 as a direct deduction from the debt liability consistent with the presentation of a debt discount and are being amortized as interest expense using the effective interest method over the life of the loan.

In connection with the Horizon Credit Agreement, the Company incurred financing fees and expenses totaling $175,000 which are recorded and classified as debt discount. In addition, the Company paid loan origination fees of $100,000 which has been recorded and classified as debt discount. These debt discount amounts totaling $782,116 are being amortized as interest expense using the effective interest method over the life of the loan. Also, in connection with each of the Horizon Credit Agreements, the Company is required to pay an end of term charge equal to 4.0% of the original loan amount at time of maturity. Therefore, these amounts totaling $400,000 are being amortized as interest expense using the effective interest method over the life of the loan.

During 2019, the Company incurred $1,006,760 in interest expense and amortized $386,640 respectively, as interest expense for debt discounts and end of term charges in connection with the Horizon Credit Agreement. During 2018, the Company incurred $512,872 in interest expense and amortized $199,153 respectively, as interest expense for debt discounts and end of term charges in connection with the Horizon Credit Agreement.

Following is a schedule of future principle payments, net of unamortized debt discounts and amortized end of term charges, due on the Horizon Credit Agreement:

	For the year ending December 31,
2020	$	2,083,334
2021		4,583,333
2022		3,333,333
2023 and thereafter		-
Subtotal of future principle payments		10,000,000
Unamortized debt issuance costs, net		(196,323	)
Total	$	9,803,677

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

9. INCOME TAXES

On December 22, 2017, the President of the United States signed into law the Tax Reform Act. The Tax Reform Act significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a quasi-territorial tax system, providing a one -time transition toll charge on foreign earnings, creating a new limitation on the deductibility of interest expenses and modifying the limitation on officer compensation. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018.

The income tax provision (benefit) for the years ended December 31, 2019 and 2018 consists of the following:

	2019			2018
Federal
Current	$	-		$	-
Deferred		-			-
State and Local		-			-
Current		-			(10,419,115	)
Deferred		(1,819,324	)		-
Effective tax rate	$	(1,819,324	)		(10,419,115	)

A reconciliation of the Company’s statutory tax rate to the effective rate for the years ended December 31, 2019 and 2018 is as follows:

	2019			2018
Federal statutory rate		21.0	%		21.0	%
State taxes, net of federal tax benefit		12.2			36.9
Permanent differences		(4.5	)		(3.8	)
Other		(7.0	)		(9.4	)
Change in valuation allowance and deferred rate change, net		(12.0	)		2.0
Effective tax rate		9.7	%		46.7	%

The components of the Company’s deferred tax asset as of December 31, 2019 and 2018 are as follows:

	December 31,
	2019			2018
Net operating loss carryforwards	$	58,243,000		$	51,498,000
Other Deferred tax assets, net		254,283			1,092,000
Subtotal		58,497,283			52,590,000
Valuation allowance		(56,497,283	)		(52,590,000	)
Total deferred tax asset	$	1,819,324		$	-

The evaluation of the realizability of such deferred tax assets in future periods is made based upon a variety of factors that affect the Company’s ability to generate future taxable income, such as intent and ability to sell assets and historical and projected operating performance. As of December 31, 2019, the Company has established a valuation reserve for its deferred income tax assets other than those related to its New Jersey NOLs. At December 31, 2019, after its evaluation of its New Jersey NOL’s as discussed more fully below, reduced the valuation reserve and recognized $1.8 million as a deferred tax asset. Such tax assets are available to be recognized and benefit future periods. As of December 31, 2019, the Company had net operating losses of approximately $289 million of which $247 million, if unused, will expire starting in 2023 through 2037. The Federal net operating loss generated for the year ended December 31, 2018 of approximately $25.8 million can be carried forward indefinitely. However, the deduction for net operating losses incurred in tax years beginning after January 1, 2018 is limited to 80% of annual taxable income

During 2019, 2018 and in prior years, the Company performed analyses to determine if there were changes in ownership, as defined by Section 382 of the Internal Revenue Code that would limit its ability to utilize certain net operating loss and tax credit carry forwards. The Company determined that it experienced ownership changes, as defined by Section 382, in connection with certain common stock offerings in July 2011, February 2013, June 2013, June 2015, February 2017, June 2017, October 2017 and August 2018. As a result, the utilization of the Company’s federal tax net operating loss carry forwards generated prior to the ownership changes are limited. As of December 31, 2018, the Company has net operating loss carry forwards for U.S. federal and state tax purposes of approximately $233 million, before excluding net operating losses that have been limited as a result of Section 382 limitations. The annual limitation due to Section 382 for net operating loss carry forward utilization is approximately $4.2 million per year for approximately $90 million in net operating loss carry forwards existing at the ownership change occurring in July 2011, approximately $1.4 million per year for approximately $34 million of additional net operating losses occurring from July 2011 to the ownership change that occurred in February 2013, approximately $1.5 million per year for approximately $4 million of additional net operating losses occurring from February 2013 to the ownership change that occurred in June 2013, approximately $1.6 million per year for approximately $40 million of additional net operating losses occurring from June 2013 to the ownership change that occurred in June 2015, approximately $0.3 million per year for approximately $35 million of additional net operating losses occurring from June 2015 to the ownership change that occurred in February 2017, approximately $0.3 million per year for approximately $7 million of additional net operating losses occurring from February 2017 to the ownership change that occurred in June 2017, approximately $0.8 million per year for approximately $5 million of additional net operating losses occurring from June 2017 to the ownership change that occurred in October 2017, and approximately $1.5 million per year for approximately $30 million of additional net operating losses occurring from October 2017 to the ownership change that occurred in August 2018. The utilization of these net operating loss carry forwards may be further limited if the Company experiences future ownership changes as defined in Section 382 of the Internal Revenue Code.

Sale of New Jersey Net Operating Losses

During 2019 and 2018, the Company received approval to sell a portion of the Company’s New Jersey NOLs as part of the Technology Business Tax Certificate Program sponsored by The New Jersey Economic Development Authority. Under the program, emerging biotechnology companies with unused NOLs and unused research and development credits are allowed to sell these benefits to other companies. During the first quarter of 2020, the Company entered into an agreement to sell these approved portion of these New Jersey NOL’s for $1.8 million. At December 31, 2019, the Company evaluated the valuation reserve for its tax net operating losses associated with its New Jersey NOLs and reduced the valuation reserve and recognized $1.8 million as a deferred income tax asset and an income tax benefit. The Company expects to complete the sale of these net operating losses in the second quarter of 2020. In 2018, the Company completed the sale of a portion of its New Jersey net operating losses totaling approximately $11.1 million for net proceeds of $10.4 million in December 2018. The Company has approximately $2.1 million in future tax benefits remaining under the NOL Program for future years.

Stockholders' Equity

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Stockholders' Equity

10. STOCKHOLDERS’ EQUITY

In September 2018, the Company filed with the SEC a $75 million shelf registration statement on Form S-3 (the 2018 Shelf Registration Statement) (File No. 333-227236) that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred stock. This shelf registration was declared effective on October 12, 2018 and will expire three years from that date.

Aspire Purchase Agreement

On August 31, 2018, we entered into a common stock purchase agreement (the “2018 Aspire Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”) which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $15.0 million of shares of the Company’s common stock over the 24-month term of the 2018 Aspire Purchase Agreement. On October 12, 2018, the Company filed with the SEC a prospectus supplement to the 2018 Shelf Registration Statement registering all the shares of common stock that may be offered to Aspire Capital from time to time.

Under the 2018 Aspire Purchase Agreement, on any trading day selected by the Company, the Company has the right, in its sole discretion, to present Aspire Capital with a purchase notice (each, a “Purchase Notice”), directing Aspire Capital (as principal) to purchase up to 100,000 shares of the Company’s common stock per business day, up to $15.0 million of the Company’s common stock in the aggregate at a per share price (the “Purchase Price”) equal to the lesser of:

●	the lowest sale price of the Company’s common stock on the purchase date; or

●	the arithmetic average of the three (3) lowest closing sale prices for the Company’s common stock during the ten (10) consecutive trading days ending on the trading day immediately preceding the purchase date.

The Company and Aspire Capital also may mutually agree to increase the number of shares that may be sold to as much as an additional 2,000,000 shares per business day.

In addition, on any date on which the Company submits a Purchase Notice to Aspire Capital in an amount equal to at least 100,000 shares, the Company also has the right, in its sole discretion, to present Aspire Capital with a volume-weighted average price purchase notice (each, a “VWAP Purchase Notice”) directing Aspire Capital to purchase an amount of stock equal to up to 30% of the aggregate shares of the Company’s common stock traded on its principal market on the next trading day (the “VWAP Purchase Date”), subject to a maximum number of shares the Company may determine. The purchase price per share pursuant to such VWAP Purchase Notice is generally 97% of the volume-weighted average price for the Company’s common stock traded on its principal market on the VWAP Purchase Date.

The Purchase Price will be adjusted for any reorganization, recapitalization, non-cash dividend, stock split, or other similar transaction occurring during the period(s) used to compute the Purchase Price. The Company may deliver multiple Purchase Notices and VWAP Purchase Notices to Aspire Capital from time to time during the term of the Purchase Agreement, so long as the most recent purchase has been completed.

There are no trading volume requirements or restrictions under the 2018 Aspire Purchase Agreement, and the Company will control the timing and amount of sales of the Company’s common stock to Aspire Capital. Aspire Capital has no right to require any sales by the Company but is obligated to make purchases from the Company as directed by the Company in accordance with the 2018 Aspire Purchase Agreement. There are no limitations on use of proceeds, financial or business covenants, restrictions on future funding, rights of first refusal, participation rights, penalties or liquidated damages in the Aspire Purchase Agreement. In consideration for entering into the 2018 Aspire Purchase Agreement, concurrently with the execution of the 2018 Aspire Purchase Agreement, the Company issued to Aspire Capital 164,835 shares of the Company’s common stock (the “2018 Commitment Shares”). The Company’s policy is to record specific incremental costs directly attributable to an offering as a charge against the gross proceeds, if any, when the offering becomes effective. The 2018 Commitment Shares valued at $450,000 were recorded in September 2018 as costs of equity financing and charged against additional paid-in capital. The 2018 Aspire Purchase Agreement may be terminated by the Company at any time, at its discretion, without any cost to the Company. Aspire Capital has agreed that neither it nor any of its agents, representatives and affiliates shall engage in any direct or indirect short-selling or hedging of the Company’s common stock during any time prior to the termination of the 2018 Aspire Purchase Agreement. Any proceeds from the Company receives under the 2018 Aspire Purchase Agreement are expected to be used for working capital and general corporate purposes. During 2018, the Company sold and issued an aggregate of 100,000 shares under the 2018 Aspire Purchase Agreement, receiving approximately $0.2 million. During 2019, the Company sold and issued an aggregate of 3.3 million shares under the 2018 Aspire Purchase Agreement, receiving approximately $6.3 million. As a result of the Company and Aspire Capital entering into a new purchase agreement on October 28, 2019 discussed in the next paragraph, the 2018 Aspire Purchase Agreement was terminated.

On October 28, 2019, Company, entered into a new common stock purchase agreement (the “2019 Aspire Purchase Agreement”) with Aspire Capital which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over the 24-month term of the 2019 Aspire Purchase Agreement. Concurrently with entering into the 2019 Aspire Purchase Agreement, the Company also entered into a registration rights agreement with Aspire Capital (the “Registration Rights Agreement”), in which the Company agreed to file one or more registration statements, as permissible and necessary to register under the Securities Act of 1933, as amended (the “Securities Act”), registering the sale of the shares of the Company’s common stock that have been and may be issued to Aspire Capital under the 2019 Aspire Purchase Agreement. On November 8, 2019, the Company filed with the SEC a Registration Statement on Form S-1 registering all the shares of common stock that may be offered to Aspire Capital from time to time under the 2019 Aspire Purchase Agreement.

The terms and conditions pursuant to the 2019 Aspire Purchase Agreement are substantially similar to the 2018 Aspire Purchase Agreement and the more significant terms are restated as follows:

●

Under the terms of the 2019 Aspire Purchase Agreement, on any trading day selected by the Company, the Company has the right, in its sole discretion, to present Aspire Capital with a Purchase Notice, directing Aspire Capital to purchase up to 100,000 shares of the Company’s common stock per business day, up to $10.0 million of the Company’s common stock in the aggregate at a per share Purchase Price equal to the lesser of:

	●	the lowest sale price of the Company’s common stock on the purchase date; or

	●	the arithmetic average of the three (3) lowest closing sale prices for the Company’s common stock during the ten (10) consecutive trading days ending on the trading day immediately preceding the purchase date.

	●	In addition, on any date on which the Company submits a Purchase Notice to Aspire Capital in an amount of 100,000 shares, the Company also has the right, in its sole discretion, to present Aspire Capital with a VWAP Purchase Notice directing Aspire Capital to purchase an amount of stock equal to up to 30% of the aggregate shares of the Company’s common stock traded on the VWAP Purchase Date, subject to a maximum number of shares the Company may determine. The purchase price per share pursuant to such VWAP Purchase Notice is generally 97% of the volume-weighted average price for the Company’s common stock traded on its principal market on the VWAP Purchase Date.

	●	In consideration for entering into the 2019 Aspire Purchase Agreement, the Company issued to Aspire Capital 100,000 shares of the Company’s common stock (the “2019 Commitment Shares”). The Company’s policy is to record specific incremental costs directly attributable to an offering as a charge against the gross proceeds, if any, when the offering becomes effective. The 2019 Commitment Shares will be fair valued and recorded in October 2019 as costs of equity financing and charged against additional paid-in capital.

	●	All other rights, responsibilities and conditions of the 2019 Aspire Purchase Agreement remain the same as the prior agreement in 2018.

During 2019, the Company sold and issued an aggregate of 0.5 million shares under the 2019 Aspire Purchase Agreement, receiving approximately $0.7 million. Subsequent to December 31, 2019 and through March 5, 2020 when the Company delivered notice to Aspire terminating the 2019 Aspire Purchase Agreement, the Company sold 1.0 million shares of common stock under the Aspire Purchase Agreement, receiving approximately $1.6 million in additional gross proceeds.

Capital on Demand^TM Sales Agreement

On December 4, 2018, the Company entered into a Capital on Demand^TM Sales Agreement (the “Capital on Demand Agreement”) with JonesTrading Institutional Services LLC, as sales agent (“JonesTrading”), pursuant to which the Company may offer and sell, from time to time, through JonesTrading shares of Common Stock having an aggregate offering price of up to $16.0 million. The Company intends to use the net proceeds from the offering, if any, for general corporate purposes, including research and development activities, capital expenditures and working capital.

The Company is not obligated to sell any Common Stock under the Capital on Demand Agreement and, subject to the terms and conditions of the Capital on Demand Agreement, JonesTrading will use commercially reasonable efforts, consistent with its normal trading and sales practices and applicable state and federal law, rules and regulations and the rules of The Nasdaq Capital Market, to sell Common Stock from time to time based upon Celsion’s instructions, including any price, time or size limits or other customary parameters or conditions the Company may impose. Under the Capital on Demand Agreement, JonesTrading may sell Common Stock by any method deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended.

The Capital on Demand Agreement will terminate upon the earlier of (i) the sale of all shares of our common stock subject to the Sales Agreement, and (ii) the termination of the Capital on Demand Agreement by JonesTrading or Celsion. The Capital on Demand Agreement may be terminated by JonesTrading or the Company at any time upon 10 days’ notice to the other party, or by JonesTrading at any time in certain circumstances, including the occurrence of a material adverse change in the Company.

The Company will pay JonesTrading a commission of 3.0% of the aggregate gross proceeds from each sale of Common Stock and has agreed to provide JonesTrading with customary indemnification and contribution rights.

The Shares will be issued pursuant to Celsion’s previously filed and effective Registration Statement on Form S-3 (File No. 333-227236), the base prospectus dated October 12, 2018, filed as part of such Registration Statement, and the prospectus supplement dated December 4, 2018, filed by Celsion with the Securities and Exchange Commission. During 2019, the Company sold and issued an aggregate of 0.5 million shares under the Capital on Demand Agreement, receiving approximately $1.0 million in gross proceeds. The Company did not sell any shares under the Capital on Demand Agreement as of December 31, 2018. As of December 31, 2019, the Company has approximately $15 million available under the Capital on Demand Agreement.

Controlled Equity Offering

On February 1, 2013, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “ATM Agreement”) with Cantor Fitzgerald & Co., as sales agent (“Cantor”), pursuant to which Celsion could offer and sell, from time to time, through Cantor, shares of our common stock having an aggregate offering price of up to $25.0 million (the “ATM Shares”) pursuant to the 2015 Shelf Registration Statement. Under the ATM Agreement, Cantor may sell ATM Shares by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on The Nasdaq Capital Market, on any other existing trading market for our common stock or to or through a market maker. On October 10, 2018, the Company delivered notice to Cantor terminating the ATM effective as of October 20, 2018. The Company has no further obligations under the Sales Agreement. During 2018, the Company received approximately $1.2 million in proceeds from the sale of 0.5 million shares of common stock under the ATM Agreement. From February 1, 2013 through September 30, 2018, the Company sold and issued an aggregate of 1,784,396 shares of common stock under the ATM Agreement, receiving approximately $12.8 million in gross proceeds.

Registered Direct Offering

On February 27, 2020, we entered into a Securities Purchase Agreement (the “Purchase Agreement”) with several institutional investors, pursuant to which we agreed to issue and sell, in a registered direct offering (the “February 2020 Offering”), an aggregate of 4,571,428 shares (the “Shares”) of our common stock at an offering price of $1.05 per share for gross proceeds of approximately $4.8 million before the deduction of the Placement Agent fees and offering expenses. The Shares were offered by the Company pursuant to a registration statement on Form S-3 (File No. 333-227236). The Purchase Agreement contains customary representations, warranties and agreements by the Company and customary conditions to closing. In a concurrent private placement (the “Private Placement”), the Company agreed to issue to the investors that participated in the Offering, for no additional consideration, warrants, to purchase up to 2,971,428 shares of Common Stock (the “Original Warrants”). The Original Warrants were initially exercisable six months following their and were set to expire on the five-year anniversary of such initial exercise date. The Warrants had an exercise price of $1.15 per share subject to adjustment as provided therein. On March 12, 2020 the Company entered into private exchange agreements (the “Exchange Agreements”) with holders the Warrants. Pursuant to the Exchange Agreements, in return for a higher exercise price of $1.24 per share of Common Stock, the Company issued new warrants to the Investors to purchase up to 3,200,000 shares of Common Stock (the “Exchange Warrants”) in exchange for the Original Warrants. The Exchange Warrants, like the Original Warrants, are initially exercisable six months following their issuance (the “Initial Exercise Date”) and expire on the five-year anniversary of their Initial Exercise Date. Other than having a higher exercise price, different issue date, Initial Exercise Date and expiration date, the terms of the Exchange Warrants are identical to those of the Original Warrants.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

11. STOCK-BASED COMPENSATION

The Company has long-term compensation plans that permit the granting of equity-based awards in the form of stock options, restricted stock, restricted stock units, stock appreciation rights, other stock awards, and performance awards.

At the 2018 Annual Stockholders Meeting of the Company held on May 15, 2018, stockholders approved the Celsion Corporation 2018 Stock Incentive Plan (the “2018 Plan”). The 2018 Plan, as adopted, permits the granting of 2,700,000 shares of Celsion common stock as equity awards in the form of incentive stock options, nonqualified stock options, restricted stock, restricted stock units, stock appreciation rights, other stock awards, performance awards, or in any combination of the foregoing. At the 2019 Annual Stockholders Meeting of the Company held on May 14, 2019, stockholders approved an amendment to the 2018 Plan whereby the Company increased the number of common stock shares available by 1,200,000 to a total of 3,900,000 under the 2018 Plan, as amended. Prior to the adoption of the 2018 Plan, the Company had maintained the Celsion Corporation 2007 Stock Incentive Plan (the “2007 Plan”).

The Company has issued stock awards to employees and directors in the form of stock options and restricted stock. Options are generally granted with strike prices equal to the fair market value of a share of Celsion common stock on the date of grant. Incentive stock options may be granted to purchase shares of common stock at a price not less than 100% of the fair market value of the underlying shares on the date of grant, provided that the exercise price of any incentive stock option granted to an eligible employee owning more than 10% of the outstanding stock of Celsion must be at least 110% of such fair market value on the date of grant. Only officers and key employees may receive incentive stock options.

Option and restricted stock awards vest upon terms determined by the Compensation Committee of the Board of Directors and are subject to accelerated vesting in the event of a change of control or certain terminations of employment. The Company issues new shares to satisfy its obligations from the exercise of options or the grant of restricted stock awards.

On September 28, 2018, and again on February 19, 2019, the Compensation Committee of the Board of Directors approved the grant of (i) inducement stock options (the “Inducement Option Grants”) to purchase a total of 164,004 and 140,004 shares of Celsion common stock, respectively and (ii) inducement restricted stock awards (the “Inducement Stock Grants”) totaling 19,000 and 13,000 shares of Celsion common stock to five new employees collectively. Each award has a grant date of the date of grant. Each Inducement Option Grant has an exercise price per share equal to $2.77 and $2.18 which represents the closing price of Celsion’s common stock as reported by Nasdaq on September 28, 2018 and February 19, 2019, respectively. Each Inducement Option Grant will vest over three years, with one-third vesting on the one-year anniversary of the employee’s first day of employment with the Company and one-third vesting on the second and third anniversaries thereafter, subject to the new employee’s continued service relationship with the Company on each such date. Each Inducement Option Grant has a ten-year term and is subject to the terms and conditions of the applicable stock option agreement. Each of Inducement Stock Grant will vest on the one-year anniversary of the employee’s first day of employment with the Company and are subject to the new employee’s continued service relationship with the Company through such date and is subject to the terms and conditions of the applicable restricted stock agreement.

As of December 31, 2019, there were a total of 4,580,893 shares of Celsion common stock reserved for issuance under the 2018 Plan, which were comprised of 4,130,886 shares of Celsion common stock subject to equity awards previously granted under the 2018 Plan and 2007 Plan and 450,007 shares of Celsion common stock available for future issuance under the 2018 Plan. As of December 31, 2019, there were a total of 210,006 of Celsion common stock subject to outstanding inducement awards.

Total compensation cost related to stock options and restricted stock awards was approximately $2.3 million and $4.6 million during 2019, and 2018, respectively. Of these amounts, $0.9 million and $1.5 million was charged to research and development during 2019 and 2018, respectively, and $1.4 million and $3.1 million was charged to general and administrative expenses during 2019 and 2018, respectively.

A summary of stock option awards as of December 31, 2019 and changes during the two-year period ended December 31, 2019 is presented below:

Stock Options	Number Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at January 1, 2018		703,442		$	10.34
Granted		2,629,004		$	2.26
Canceled or expired		(183,703	)	$	25.96
Outstanding at December 31, 2018		3,148,743		$	2.67
Granted		1,250,754		$	2.00
Canceled or expired		(67,355	)	$	2.50
Outstanding at December 31, 2019		4,332,142		$	2.63		8.5	$	5,882

Exercisable at December 31, 2019		2,469,033		$	2.98		8.0	$	-

A summary of the status of the Company’s non-vested restricted stock awards as of December 31, 2019 and changes during the two-year period ended December 31, 2019, is presented below:

Restricted Stock	Number Outstanding			Weighted Average Grant Date Fair Value
Non-vested stock awards outstanding at January 1, 2018		–		$	–
Granted		35,000		$	2.71
Vested and issued		(6,000	)	$	2.77
Forfeited		(6,500	)	$	2.64
Non-vested stock awards outstanding at December 31, 2018		22,500		$	2.72
Granted		29,250		$	1.99
Vested and issued		(5,000	)	$	2.14
Forfeited		(38,000	)	$	2.48
Non-vested stock awards outstanding at December 31, 2019		8,750		$	1.59

A summary of stock options outstanding at December 31, 2019 by price range is as follows:

	Options Outstanding						Options Exercisable

Range of Exercise Prices	Number		Weighted Average Remaining Contractual Term (in years)		Weighted Average Exercise Price		Number		Weighted Average Remaining Contractual Term (in years)		Weighted Average Exercise Price

Up to $5.00		3,821,470		8.4	$	2.47		2,404,611		8.0	$	2.55
Above $5.00 to $81.90		64,422		6.0	$	19.00		64,422		6.0	$	19.00
		3,885,892						2,469,033

The fair values of stock options granted were estimated at the date of grant using the Black-Scholes option pricing model. The Black-Scholes model was originally developed for use in estimating the fair value of traded options, which have different characteristics from Celsion’s stock options. The model is also sensitive to changes in assumptions, which can materially affect the fair value estimate. The Company used the following assumptions for determining the fair value of options granted under the Black-Scholes option pricing model:

	Year Ended December 31,
	2019			2018
Risk-free interest rate		2.82 to 3.02	%		2.82 to 3.02	%
Expected volatility		101.3 – 106.2	%		99.9 - 102.1	%
Expected life (in years)		7.5 to 9.3			8.5 to 10
Expected dividend yield		0.0	%		0.0	%

Expected volatilities utilized in the model are based on historical volatility of the Company’s stock price. As of December 31, 2019, there was $1.6 million of total unrecognized compensation cost related to non-vested stock-based compensation arrangements. That cost is expected to be recognized over a weighted-average period of 1.1 years.

Earn-out Milestone Liability

12 Months Ended

Dec. 31, 2019

Hercules Warrant [Member]

Earn-out Milestone Liability

12. EARN-OUT MILESTONE LIABILITY

The total aggregate purchase price for the EGEN Acquisition included potential future Earn-out Payments contingent upon achievement of certain milestones. The difference between the aggregate $30.4 million in future Earn-out Payments and the $13.9 million included in the fair value of the acquisition consideration at June 20, 2014 was based on the Company’s risk-adjusted assessment of each milestone (10% to 67%) and utilizing a discount rate based on the estimated time to achieve the milestone (1.5 to 2.5 years). The earn-out milestone liability will be fair valued at the end of each quarter and any change in their value will be recognized in the financial statements.

On March 28, 2019, the Company and EGWU, Inc, entered into the Amended Asset Purchase Agreement. Pursuant to the Amended Asset Purchase Agreement, payment of the earnout milestone liability related to the Ovarian Cancer Indication of $12.4 million has been modified. The Company has the option to make the payment as follows:

a)	$7.0 million in cash within 10 business days of achieving the milestone; or
b)	$12.4 million in cash, common stock of the Company, or a combination of either, within one year of achieving the milestone.

The Company provided EGWU, Inc. 200,000 warrants to purchase common stock at a strike price of $0.01 per warrant share as consideration for entering into this amended agreement. The warrant shares have no expiration and were fair valued at $2.00 using the closing price of a share of Celsion stock on the date of issuance offset by the exercise price and recorded as a non-cash expense in the income statement and were classified as equity on the balance sheet.

At December 31, 2019, the Company fair valued the earn-out milestone liability at $6.2 million and recognized a non-cash gain of $2.7 million during 2019 as a result of the change in the fair value of earn-out milestone liability of $8.9 million at December 31, 2018. In assessing the earnout milestone liability at December 31, 2019, the Company fair valued each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 65% and 35% probability for the $7.0 million and the $12.4 million payments, respectively.

At December 31, 2018, the Company fair valued the earn-out milestone liability at $8.9 million and recognized a non-cash gain of $3.6 million during 2018 as a result of the change in the fair value of earn-out milestone liability of $12.5 million at December 31, 2017. Included in the non-cash gain during 2018, was the reduction of the liability by $3.9 million during the third quarter of 2017 related to the write down of one of the in-process research and development assets (see Note 5) as the Company believes there is a de minimis probability of the payout of the related earn-out milestone liabilities. The fair value of the remaining earn-out milestone liabilities at December 31, 2018 was based on the Company’s risk-adjusted assessment of each milestone (80%) utilizing a discount rate based on the estimated time to achieve the milestone (1.25 years).

The following is a summary of the changes in the earn-out milestone liability for 2018 and 2019:

Balance at January 1, 2018	$	12,538,525
Non-cash gain from the adjustment for the change in fair value included in 2018 net loss		(3,630,861	)
Balance at December 31, 2018		8,907,664
Non-cash gain from the adjustment for the change in fair value included in 2019 net loss		(3,189,955	)
Balance at December 31, 2019	$	5,717,709

Warrants

12 Months Ended

Dec. 31, 2019

Warrants and Rights Note Disclosure [Abstract]

Warrants

13. WARRANTS

Warrants to purchase 1,167,064 and 13,927 shares of common stock expired during 2019 and 2018, respectively. During 2018, the Company and certain investors holding warrants to collectively purchase 1.6 million shares of the Company’s common stock, entered into warrant exchange agreements whereby the Company issued 820,714 shares of its common stock in exchange for the cancellation of the warrants.

Following is a summary of all warrant activity for the two years ended December 31, 2019:

Warrants	Number of Warrants Issued			Weighted Average Exercise Price
Warrants outstanding at January 1, 2018		3,058,402		$	5.29
Warrants issued in connection with 2018 equity transactions		190,114		$	2.63
Warrants cancelled in exchange for common stock		(1,641,427	)	$	3.04
Warrants expired during 2018		(13,927	)	$	226.24
Warrants outstanding at December 31, 2018		1,593,162		$	5.36
Warrants issued during 2019 (see Note 12)		200,000		$	0.01
Warrants expired during 2019		(1,167,064	)	$	6.32
Warrants outstanding and exercisable at December 31, 2019		626,098		$	1.87

Aggregate intrinsic value of outstanding warrants at December 31, 2019	$	340,000

Weighted average remaining contractual terms (years)		1.87

Schedule of weighted average remaining contractual terms at December 31, 2019	Number of Warrants Issued		Weighted Average Exercise Price		Weighted Average Contractual Terms Remaining

Warrants provided to EGWU, Inc (Note 12)		200,000	$	0.01	No expiration

All other warrants outstanding		426,098	$	2.74	5.3 years

Celsion Employee Benefit Plans

12 Months Ended

Dec. 31, 2019

Postemployment Benefits [Abstract]

Celsion Employee Benefit Plans

14. CELSION EMPLOYEE BENEFIT PLANS

Celsion maintains a defined-contribution plan under Section 401(k) of the Internal Revenue Code. The plan covers substantially all employees over the age of 21. Participating employees may defer a portion of their pretax earnings, up to the IRS annual contribution limit. The Company makes a matching contribution up to a maximum of 3% of an employee’s annual salary. The Company’s total matching contributions for the years ended December 31, 2019 and 2018 was $105,999 and $93,948 respectively. During 2018, the Company also provided a discretionary contribution totaling $181,999 which represented 6% of each eligible participant’s annual salary in each of 2018. This amount was paid in January 2019.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

15. LEASES

In 2011, the Company executed a lease (the “Lease”) with Brandywine Operating Partnership, L.P. (Brandywine), a Delaware limited partnership for a 10,870 square foot premises located in Lawrenceville, New Jersey and relocated its offices to Lawrenceville, New Jersey from Columbia, Maryland. The Lease had an initial term of 66 months. In late 2015, Lenox Drive Office Park LLC, purchased the real estate and office building and assumed the Lease. This Lease was set to expire on April 30, 2017. In April 2017, the Company and the landlord amended the Lease effective May 1, 2017. The 1^st Lease Amendment extended the term of the agreement for an additional 64 months, reduced the premises to 7,565 square feet, reduced the monthly rent and provided four months free rent. The monthly rent ranged from approximately $18,900 in the first year to approximately $20,500 in the final year of the 1^st Lease Amendment. The Company also had a one-time option to cancel the lease as of the 40th month after the commencement date of the 1^st Lease Amendment and must provide the landlord notice by the 28^th month of the lease. Effective January 9, 2019, the Company amended the current terms of the 1^st Lease Amendment to increase the size of the premises by 2,285 square feet to 9,850 square feet and also extended the lease term by one year to September 1, 2023. In conjunction with this 2^nd Lease Amendment, we agreed to modify our one-time option to cancel the lease as of the end of August 2021 and we must provide notice to the landlord by the end of August 2020. The monthly rent will range from approximately $25,035 in the first year to approximately $27,088 in the final year of the 2^nd Lease Amendment.

In connection with the EGEN Asset Purchase Agreement in June 2014, the Company assumed the existing lease with another landlord for an 11,500 square foot premises located in Huntsville Alabama. In January 2018, the Company and the Huntsville landlord entered into a new 60-month lease which reduced the premises to 9,049 square feet with rent payments of approximately $18,100 per month.

As previously mentioned in Note 4, we adopted ASC Topic 842 on January 1, 2019 using the modified retrospective transition method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with our historic accounting under Topic 840, Leases. The standard had a material impact on our Consolidated Condensed Balance Sheet but had no impact on our consolidated net earnings and cash flows. The most significant impact of adopting ASC Topic 842 was the recognition of the right-of-use (ROU) asset and lease liabilities for operating leases, which are presented in the following three-line items on the Consolidated Condensed Balance Sheet: (i) operating lease right-of-use asset; (ii) current operating lease liabilities; and (iii) operating lease liabilities. Therefore, on date of adoption of ASC Topic 842, the Company recognized a ROU asset of $1.4 million, operating lease liabilities, current and non-current collectively, of $1.5 million and reduced other liabilities by approximately $0.1 million. We elected the package of practical expedients for leases that commenced before the effective date of ASC Topic 842 whereby we elected to not reassess the following: (i) whether any expired or existing contracts contain leases; (ii) the lease classification for any expired or existing leases; and (iii) initial direct costs for any existing leases. In addition, we have lease agreements with lease and non-lease components, and we have elected the practical expedient for all underlying asset classes and account for them as a single lease component. We have no finance leases. We determine if an arrangement is a lease at inception. We have operating leases for office space and research and development facilities. Neither of our leases include options to renew, however, one contains an option for early termination. We considered the option of early termination in measurement of right-of-use assets and lease liabilities and we determined it is not reasonably certain to be terminated. In connection with the 2^nd Lease Amendment for the New Jersey office lease in January 2019, the Company considered this as one modified lease and not as two separate leases. Therefore, in January 2019, the Company determined this lease was an operating lease and remeasured the ROU asset and lease liability. Therefore, the Company increased the ROU asset and operating lease liabilities by $0.4 million to $1.8 million and $1.9 million, respectively.

Following is a table of the lease payments and maturity of our operating lease liabilities as of December 31, 2019:

	For the year ending December 31,
2020	$	525,809
2021		530,734
2022		535,579
2023		233,117
2024 and thereafter		-
Subtotal future lease payments		1,825,239
Less imputed interest		(293,790	)
Total lease liabilities	$	1,531,450

Weighted average remaining life		3.45 years

Weighted average discount rate		9.98	%

For the 2019, operating lease expense was $522,380 and cash paid for operating leases included in operating cash flows was $485,848. For 2018, operating lease expense was $450,430 and cash paid for operating leases included in operating cash flows was $457,321.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

16. COMMITMENTS AND CONTINGENCIES

On September 20, 2019, a purported stockholder of the Company filed a derivative and putative class action lawsuit against the Company and certain officers and directors (the “Shareholder Action”). The Shareholder Action alleges breaches of fiduciary duty in connection with the shareholder approval process associated with the 2018 Stock Incentive Plan. The matter is in the early stages and the ultimate outcome of this matter is not currently determinable at this time.

Licenses of Intellectual Property and Patents

12 Months Ended

Dec. 31, 2019

Intangible Assets, Net (Including Goodwill) [Abstract]

Licenses of Intellectual Property and Patents

17. LICENSES OF INTELLECTUAL PROPERTY AND PATENTS

On November 10, 1999, the Company entered into a license agreement with Duke University (“Duke”) under which the Company received worldwide exclusive rights (subject to certain exceptions) to commercialize and use Duke’s thermally sensitive liposome technology. The license agreement contains annual royalty and minimum payment provisions due on net sales. The agreement also required milestone-based royalty payments measured by various events, including product development stages, FDA applications and approvals, foreign marketing approvals and achievement of significant sales. However, in lieu of such milestone-based cash payments, Duke agreed to accept shares of the Company’s common stock to be issued in installments at the time each milestone payment is due, with each installment of shares to be calculated at the average closing price of the common stock during the 20 trading days prior to issuance.

The total number of shares issuable to Duke under these provisions is subject to adjustment in certain cases, and Duke has piggyback registration rights for public offerings taking place more than one year after the effective date of the license agreement. On January 31, 2003, the Company issued 253,691 shares of common stock to Duke University valued at $2.2 million as payment for milestone-based royalties under this license agreement. An amendment to the Duke license agreement contains certain development and regulatory milestones, and other performance requirements that the Company has met with respect to the use of the licensed technologies. The Company will be obligated to make royalty payments based on sales to Duke upon commercialization, until the last of the Duke patents expire. For the years ended December 31, 2019 and 2018, the Company has not incurred any expense under this agreement and will not incur any future liabilities until commercial sales commence.

Under the November 1999 license agreement with Duke, the Company has rights to the thermally sensitive liposome technology, including Duke’s U.S. patents covering the technology as well as all foreign counter parts and related pending applications. Foreign counterpart applications have been issued in the EU, Hong Kong, Australia and Canada and have been allowed in Japan. The EU patent has been validated in Austria, Belgium, France, Germany, Great Britain, Italy, Luxembourg, Monaco, Spain and Switzerland. In addition, the Duke license agreement provides the Company with rights to multiple issued and pending U.S. patents related to the formulation, method of making and use of heat sensitive liposomes. The Company’s rights under the license agreement with Duke extend for the life of the last-to-expire of the licensed patents.

The Company has licensed from Valentis, CA certain global rights covering the use of pegylation for temperature sensitive liposomes.

In addition to the rights available to the Company under completed or pending license agreements, the Company is actively pursuing patent protection for technologies developed by the Company. Among these patents is a family of pending US and international patent applications which seek to protect the Company’s proprietary method of storing ThermoDox® which is critical for worldwide distribution channels.

ThermoDox® is a registered trademark in the U.S., Argentina, Australia, Canada, China, Columbia, the EU Member States: (Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Korea, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, the United Kingdom), Hong Kong, Israel, Japan, New Zealand, Peru, Philippines, Russia, Singapore, South Korea and Taiwan. The Company has registered transliterations of ThermoDox® in China, Hong Kong, Japan, Singapore, South Korea and Taiwan. The Company has an additional 14 trademark protection applications pending for ThermoDox® in countries world-wide.

Finally, through proprietary information agreements with employees, consultants and others, the Company seeks to protect its own proprietary know-how and trade secrets. The Company cannot offer assurances that these confidentiality agreements will not be breached, that the Company will have adequate remedies for any breach, or that these agreements, even if fully enforced, will be adequate to prevent third-party use of the Company’s proprietary technology. Similarly, the Company cannot guarantee that technology rights licensed to it by others will not be successfully challenged or circumvented by third parties, or that the rights granted will provide the Company with adequate protection.

Technology Development and Licensing Agreements

12 Months Ended

Dec. 31, 2019

Technology Development And Licensing Agreements

Technology Development and Licensing Agreements

18. TECHNOLOGY DEVELOPMENT AND LICENSING AGREEMENTS

On May 7, 2012, the Company entered into a long-term commercial supply agreement with Zhejiang Hisun Pharmaceutical Co. Ltd. (Hisun) for the production of ThermoDox® in the China territory. In accordance with the terms of the agreement, Hisun will be responsible for providing all of the technical and regulatory support services, including the costs of all technical transfer, registration and bioequivalence studies, technical transfer costs, Celsion consultative support costs and the purchase of any necessary equipment and additional facility costs necessary to support capacity requirements for the manufacture of ThermoDox®. Celsion will repay Hisun for the aggregate amount of these development costs and fees commencing on the successful completion of three registration batches of ThermoDox®. Hisun is also obligated to certain performance requirements under the agreement. The agreement will initially be limited to a percentage of the production requirements of ThermoDox® in the China territory with Hisun retaining an option for additional global supply after local regulatory approval in the China territory. In addition, Hisun will collaborate with Celsion around the regulatory approval activities for ThermoDox® with the China State Food and Drug Administration (CHINA FDA).

On January 18, 2013, we entered into a technology development contract with Hisun, pursuant to which Hisun paid us a non-refundable research and development fee of $5 million to support our development of ThermoDox ^® in mainland China, Hong Kong and Macau (the China territory). Following our announcement on January 31, 2013 that the HEAT study failed to meet its primary endpoint, Celsion and Hisun have agreed that the Technology Development Contract entered into on January 18, 2013 will remain in effect while the parties continue to collaborate and are evaluating the next steps in relation to ThermoDox^®, which include the sub-group analysis of patients in the Phase III HEAT Study for the hepatocellular carcinoma clinical indication and other activities to further the development of ThermoDox ^® for the Greater China market. The $5.0 million received as a non-refundable payment from Hisun in the first quarter 2013 has been recorded to deferred revenue and will continue to be amortized over the 10 -year term of the agreement, until such time as the parties find a mutually acceptable path forward on the development of ThermoDox ^® based on findings of the ongoing post-study analysis of the HEAT Study data.

Subsequent Events

12 Months Ended

Dec. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

19. SUBSEQUENT EVENTS

As more fully discussed in Note 10, the Company sold 4.6 million shares of common stock for gross proceeds of $4.8 million under the February 2020 Offering. On March 5, 2020, the Company also terminated the 2019 Aspire Purchase Agreement.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Description of Business

Description of Business

Basis of Presentation

Basis of Presentation

Use of Estimates

Use of Estimates

Revenue Recognition

Revenue Recognition

Cash and Cash Equivalents

Cash and Cash Equivalents

Cash and cash equivalents include cash on hand and investments purchased with an original maturity of three months or less. A portion of these funds are not covered by FDIC insurance.

Fair Value of Investment in Debt Securities

Fair Value of Investment in Debt Securities

The carrying values of investment securities approximate their respective fair values.

Short Term Investments

Short Term Investments

Property and Equipment

Property and Equipment

Deposits

Deposits

Deposits include real property security deposits and other deposits which are contractually required and of a long-term nature.

In-Process Research and Development, Other Intangible Assets and Goodwill

In-Process Research and Development, Other Intangible Assets and Goodwill

Impairment or Disposal of Long-Lived Assets

Impairment or Disposal of Long-Lived Assets

Comprehensive Income (Loss)

Comprehensive Income (Loss)

Research and Development

Research and Development

Net Loss Per Common Share

Net Loss Per Common Share

Income Taxes

Income Taxes

Stock-Based Compensation

Stock-Based Compensation

Recent Accounting Pronouncements

Recent Accounting Pronouncements

●	ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which amends certain narrow aspects of the guidance issued in ASU 2016-02; and

●	ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component.

Investments in Debt Securities Available For Sale (Tables)

12 Months Ended

Dec. 31, 2019

Short-term Investments [Abstract]

Schedule of Cost, Fair Value and Maturities of Short Term Investments

A summary of the cost, fair value and maturities of the Company’s short-term investments is as follows:

	December 31, 2019				December 31, 2018
	Cost		Fair Value		Cost		Fair Value
Short-term investments
Corporate debt securities	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998
Total	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998

	December 31, 2019				December 31, 2018
	Cost		Fair Value		Cost		Fair Value
Short-term investment maturities
Within 3 months	$	7,943,108	$	7,985,886	$	5,383,488	$	5,393,743
Between 3-12 months		-		-		8,844,638		8,864,255
Total	$	7,943,108	$	7,985,886	$	14,228,126	$	14,257,998

Summary of Investment Securities Gross Unrealized Gains (Losses)

The Company has reviewed individual securities to determine whether a decline in fair value below the amortizable cost basis is other than temporary.

	December 31, 2019				December 31, 2018
Available for sale securities (all unrealized holding gains and losses are less than 12 months at date of measurement)	Fair Value		Unrealized Holding Gains (Losses)		Fair Value		Unrealized Holding Gains (Losses)

Investments in debt securities with unrealized gains	$	7,985,886	$	42,778	$	7,515,676	$	38,068
Investments in debt securities with unrealized losses		-		-		6,742,322		(8,196	)
Total	$	7,985,886	$	42,778	$	14,257,998	$	29,872

Summary of Net Realized Losses On Sales of Available for Sale Securities and Investment Income Interest and Dividends

Investment income, which includes net realized losses on sales of available for sale securities and investment income interest and dividends, is summarized as follows:

	2019		2018
Interest and dividends accrued and paid	$	442,987	$	363,846
Realized gains (losses)		57,895		(10,164	)
Investment income net	$	500,882	$	353,682

Fair Values of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Assets and liabilities measured at fair value are summarized below:

	Total Fair Value		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:

Recurring items as of December 31, 2019
Corporate debt securities, available for sale	$	7,985,886	$	─	$	7,985,886	$	─

Recurring items as of December 31, 2018
Corporate debt securities, available for sale	$	14,257,998	$	─	$	14,257,998	$	─

Liabilities:

Recurring items as of December 31, 2019
Earn-out milestone liability (Note 13)	$	5,717,709	$	─	$	─	$	5,717,709

Recurring items as of December 31, 2018
Earn-out milestone liability (Note 13)	$	8,907,664	$	─	$	─	$	8,907,664

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Intangible Assets, Net (Including Goodwill) [Abstract]

Schedule of Future Amortization Amounts During the Remaining Life

Following is a schedule of future amortization amounts during the remaining life of the Covenant Not to Compete.

	Year Ended December 31,
2020	$	227,316
2021		113,660
Total	$	340,976

Schedule of Fair Value of Assets Acquired

Following is a summary of the net fair value of the assets acquired in the EGEN acquisition for the two years ended December 31, 2019:

	IPR&D			Goodwill		Covenant Not to Compete

Balance at January 1, 2018, net	$	20,246,491		$	1,976,101	$	795,608
Amortization		-			-		(227,316	)
Impairment charge		(4,510,000	)		-		-
Balance at December 31, 2018, net		15,736,491			1,976,101		568,292
Amortization		-			-		(227,316	)
Balance at December 31, 2019, net	$	15,736,491		$	1,976,101	$	340,976

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

	Year Ended December 31,
	2019			2018
Machinery and equipment (5-7 year life)	$	2,831,564		$	2,596,170
Furniture and fixtures (3-5 year life)		327,278			267,712
Leasehold improvements (5-7 year life)		343,202			289,004
		3,502,044			3,152,886
Less accumulated depreciation and amortization		(3,096,681	)		(2,968,259	)
Total	$	405,363		$	184,627

Other Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Payables and Accruals [Abstract]

Schedule of Other Accrued Liabilities

Other accrued liabilities at December 31, 2019 and 2018 include the following:

	Year Ended December 31,
	2019		2018
Amounts due to contract research organizations and other contractual agreements	$	475,440	$	749,369
Accrued payroll and related benefits		1,604,541		1,592,590
Accrued professional fees		204,155		198,654
Other		19,411		45,285
Total	$	2,303,547	$	2,585,898

Note Payable (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Future Principle Payments, Net of Unamortized Debt Discounts

Following is a schedule of future principle payments, net of unamortized debt discounts and amortized end of term charges, due on the Horizon Credit Agreement:

	For the year ending December 31,
2020	$	2,083,334
2021		4,583,333
2022		3,333,333
2023 and thereafter		-
Subtotal of future principle payments		10,000,000
Unamortized debt issuance costs, net		(196,323	)
Total	$	9,803,677

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Income Tax Provision (Benefit)

The income tax provision (benefit) for the years ended December 31, 2019 and 2018 consists of the following:

	2019			2018
Federal
Current	$	-		$	-
Deferred		-			-
State and Local		-			-
Current		-			(10,419,115	)
Deferred		(1,819,324	)		-
Effective tax rate	$	(1,819,324	)		(10,419,115	)

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the Company’s statutory tax rate to the effective rate for the years ended December 31, 2019 and 2018 is as follows:

	2019			2018
Federal statutory rate		21.0	%		21.0	%
State taxes, net of federal tax benefit		12.2			36.9
Permanent differences		(4.5	)		(3.8	)
Other		(7.0	)		(9.4	)
Change in valuation allowance and deferred rate change, net		(12.0	)		2.0
Effective tax rate		9.7	%		46.7	%

Schedule of Deferred Tax Assets and Liabilities

The components of the Company’s deferred tax asset as of December 31, 2019 and 2018 are as follows:

	December 31,
	2019			2018
Net operating loss carryforwards	$	58,243,000		$	51,498,000
Other Deferred tax assets, net		254,283			1,092,000
Subtotal		58,497,283			52,590,000
Valuation allowance		(56,497,283	)		(52,590,000	)
Total deferred tax asset	$	1,819,324		$	-

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Summary of Stock Option Awards

A summary of stock option awards as of December 31, 2019 and changes during the two-year period ended December 31, 2019 is presented below:

Stock Options	Number Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at January 1, 2018		703,442		$	10.34
Granted		2,629,004		$	2.26
Canceled or expired		(183,703	)	$	25.96
Outstanding at December 31, 2018		3,148,743		$	2.67
Granted		1,250,754		$	2.00
Canceled or expired		(67,355	)	$	2.50
Outstanding at December 31, 2019		4,332,142		$	2.63		8.5	$	5,882

Exercisable at December 31, 2019		2,469,033		$	2.98		8.0	$	-

Summary of Non-vested Restricted Stock Awards

A summary of the status of the Company’s non-vested restricted stock awards as of December 31, 2019 and changes during the two-year period ended December 31, 2019, is presented below:

Restricted Stock	Number Outstanding			Weighted Average Grant Date Fair Value
Non-vested stock awards outstanding at January 1, 2018		–		$	–
Granted		35,000		$	2.71
Vested and issued		(6,000	)	$	2.77
Forfeited		(6,500	)	$	2.64
Non-vested stock awards outstanding at December 31, 2018		22,500		$	2.72
Granted		29,250		$	1.99
Vested and issued		(5,000	)	$	2.14
Forfeited		(38,000	)	$	2.48
Non-vested stock awards outstanding at December 31, 2019		8,750		$	1.59

Summary of Stock Options Outstanding

A summary of stock options outstanding at December 31, 2019 by price range is as follows:

	Options Outstanding						Options Exercisable

Range of Exercise Prices	Number		Weighted Average Remaining Contractual Term (in years)		Weighted Average Exercise Price		Number		Weighted Average Remaining Contractual Term (in years)		Weighted Average Exercise Price

Up to $5.00		3,821,470		8.4	$	2.47		2,404,611		8.0	$	2.55
Above $5.00 to $81.90		64,422		6.0	$	19.00		64,422		6.0	$	19.00
		3,885,892						2,469,033

Schedule of Assumptions Used to Determine Fair Value of Options Granted

The Company used the following assumptions for determining the fair value of options granted under the Black-Scholes option pricing model:

	Year Ended December 31,
	2019			2018
Risk-free interest rate		2.82 to 3.02	%		2.82 to 3.02	%
Expected volatility		101.3 – 106.2	%		99.9 - 102.1	%
Expected life (in years)		7.5 to 9.3			8.5 to 10
Expected dividend yield		0.0	%		0.0	%

Earn-out Milestone Liability (Tables)

12 Months Ended

Dec. 31, 2019

Hercules Warrant [Member]

Schedule of Changes in Earn-out Milestone Liability

The following is a summary of the changes in the earn-out milestone liability for 2018 and 2019:

Balance at January 1, 2018	$	12,538,525
Non-cash gain from the adjustment for the change in fair value included in 2018 net loss		(3,630,861	)
Balance at December 31, 2018		8,907,664
Non-cash gain from the adjustment for the change in fair value included in 2019 net loss		(3,189,955	)
Balance at December 31, 2019	$	5,717,709

Warrants (Tables)

12 Months Ended

Dec. 31, 2019

Warrants and Rights Note Disclosure [Abstract]

Summary of Warrant Activity

Following is a summary of all warrant activity for the two years ended December 31, 2019:

Warrants	Number of Warrants Issued			Weighted Average Exercise Price
Warrants outstanding at January 1, 2018		3,058,402		$	5.29
Warrants issued in connection with 2018 equity transactions		190,114		$	2.63
Warrants cancelled in exchange for common stock		(1,641,427	)	$	3.04
Warrants expired during 2018		(13,927	)	$	226.24
Warrants outstanding at December 31, 2018		1,593,162		$	5.36
Warrants issued during 2019 (see Note 12)		200,000		$	0.01
Warrants expired during 2019		(1,167,064	)	$	6.32
Warrants outstanding and exercisable at December 31, 2019		626,098		$	1.87

Aggregate intrinsic value of outstanding warrants at December 31, 2019	$	340,000

Weighted average remaining contractual terms (years)		1.87

Schedule of Weighted Average Remaining Contractual Terms

Schedule of weighted average remaining contractual terms at December 31, 2019	Number of Warrants Issued		Weighted Average Exercise Price		Weighted Average Contractual Terms Remaining

Warrants provided to EGWU, Inc (Note 12)		200,000	$	0.01	No expiration

All other warrants outstanding		426,098	$	2.74	5.3 years

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Lease Payments and Maturity of Our Operating Lease Liabilities

Following is a table of the lease payments and maturity of our operating lease liabilities as of December 31, 2019:

	For the year ending December 31,
2020	$	525,809
2021		530,734
2022		535,579
2023		233,117
2024 and thereafter		-
Subtotal future lease payments		1,825,239
Less imputed interest		(293,790	)
Total lease liabilities	$	1,531,450

Weighted average remaining life		3.45 years

Weighted average discount rate		9.98	%

Summary of Significant Accounting Policies (Details Narrative) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 02, 2019	Dec. 31, 2017
Accounts receivable
Depreciation		$ 128,500	$ 130,000
Number of shares of common stock issuable upon exercise of warrants and equity awards		4,766,990	4,764,405
Warrants exercise price		$ 0.01
Number of shares of common stock issued in calculation basic loss per share		200,000
Right-of-use assets		$ 1,431,640		$ 400,000
Related lease liabilities		1,531,450		$ 1,900,000
Other liabilities		100,000
Subsequent Event [Member]
Net proceeds from sale of net operating losses	$ 1,800,000
New Jersey [Member]
Tax benefits of EDA		1,900,000	10,400,000
Net proceeds from sale of net operating losses		1,800,000	11,100,000
Hisun Agreement [Member]
Contract liabilities		$ 1,500,000	$ 2,000,000		$ 2,500,000

Financial Condition (Details Narrative) - USD ($)	6 Months Ended	12 Months Ended
Financial Condition (Details Narrative) - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Cumulated net losses		$ (290,516,780)	$ (273,665,247)
Cash, investment securities and interest receivable		16,700,000
Raised in equity financing		6,400,000
Proceeds from available future sale of equity under common stock purchase agreement		15,000,000
Subsequent Event [Member]
Net proceeds from sale of net operating losses	$ 1,800,000
New Jersey [Member]
Tax benefits of EDA		1,900,000	10,400,000
Net proceeds from sale of net operating losses		1,800,000	$ 11,100,000
Future tax benefits		$ 2,100,000

Investments in Debt Securities Available for Sale (Details Narrative) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Short-term investments - Fair Value	$ 7,985,886	$ 14,257,998
Corporate Debt Securities [Member]
Short-term investments - Fair Value	7,985,886	14,257,998
Short-term Investments [Member] \| Corporate Debt Securities [Member]
Short-term investments - Fair Value	$ 7,985,886	$ 14,257,998

Investments in Debt Securities Available for Sale - Schedule of Cost, Fair Value and Maturities of Short Term Investments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Short-term investments - Cost	$ 7,943,108	$ 14,228,126
Short-term investments - Fair Value	7,985,886	14,257,998
Short-term investment maturities - Within 3 months, cost	7,943,108	5,383,488
Short-term investment maturities - Between 3-12 months, cost		8,844,638
Total, cost	7,943,108	14,228,126
Short-term investment maturities - Within 3 months, fair value	7,985,886	5,393,743
Short-term investment maturities - Between 3-12 months, fair value		8,864,255
Total, fair value	7,985,886	14,257,998
Corporate Debt Securities [Member]
Short-term investments - Cost	7,943,108	14,228,126
Short-term investments - Fair Value	$ 7,985,886	$ 14,257,998

Investments in Debt Securities Available for Sale - Summary of Investment Securities Gross Unrealized Gains (Losses) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Investments in debt securities with unrealized gains, Less than 12 months , Fair Value	$ 7,985,886	$ 7,515,676
Investments in debt securities with unrealized losses, Less than 12 months, unrealized losses, Fair Value		6,742,322
Investment securities - available for sale, Fair Value	7,985,886	14,257,998
Investments in debt securities with unrealized gains, Less than 12 months, Unrealized Holding Gains (Losses)	42,778	38,068
Investments in debt securities with unrealized losses, Less than 12 months, Unrealized Holding Gains (Losses)		(8,196)
Unrealized Holding Gains (Losses)	$ 42,778	$ 29,872

Investments in Debt Securities Available for Sale - Summary of Net Realized Losses On Sales of Available for Sale Securities and Investment Income Interest and Dividends (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Interest and dividends accrued and paid	$ 442,987	$ 363,846
Realized gains (losses	57,895	(10,164)
Investment income, net	$ 500,882	$ 353,682

Fair Values of Financial Instruments - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Investment securities, available for sale	$ 7,985,886	$ 14,257,998
Earn-out milestone liability	5,717,709	8,907,664
Corporate Debt Securities [Member]
Investment securities, available for sale	7,985,886	14,257,998
Fair Value, Measurements, Recurring [Member]
Earn-out milestone liability	5,717,709	8,907,664
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Earn-out milestone liability
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Earn-out milestone liability
Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Earn-out milestone liability	5,717,709	8,907,664
Fair Value, Measurements, Recurring [Member] \| Corporate Debt Securities [Member]
Investment securities, available for sale	7,985,886	14,257,998
Fair Value, Measurements, Recurring [Member] \| Corporate Debt Securities [Member] \| Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Investment securities, available for sale
Fair Value, Measurements, Recurring [Member] \| Corporate Debt Securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investment securities, available for sale	7,985,886	14,257,998
Fair Value, Measurements, Recurring [Member] \| Corporate Debt Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investment securities, available for sale

Intangible Assets (Details Narrative) - USD ($)					12 Months Ended
Intangible Assets (Details Narrative) - USD ($)	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2016	Jun. 20, 2014	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset impairment charges, total					$ 2,400,000
Business combination, consideration transferred, liabilities incurred						$ 4,500,000	$ 2,500,000
IPR&D costs					2,400,000	2,400,000
Finite-lived intangible assets, net					340,976	568,292
2018 Aspire Purchase Agreements [Member]
Finite-lived intangible assets, net					340,976
Finite-lived intangible assets, accumulated amortization					1,250,238
Aspire Purchase Agreement [Member]
Finite-lived intangible assets, net						568,292
Finite-lived intangible assets, accumulated amortization						1,022,922
IPR&D Drug Technology Platforms [Member]
Asset impairment charges, total			$ 1,400,000
EGEN Inc [Member]
Business combination, consideration transferred, liabilities incurred				$ 13,900,000
Goodwill, acquisition					2,000,000
EGEN Inc [Member] \| Purchase Agreement [Member]
Finite-lived intangible assets acquired					$ 1,600,000
Finite-lived intangible asset, useful life					7 years
Amortization expense					$ 227,316	227,316
EGEN Inc [Member] \| Glioblastoma Multiforme Brain Cancer [Member]
Asset impairment charges, total	$ 9,400,000	$ 9,400,000
EGEN Inc [Member] \| Ovarian Cancer [Member]
Finite-lived intangible assets, net					13,300,000	$ 13,300,000
EGEN Inc [Member] \| IPR&D Drug Technology Platforms [Member]
Indefinite lived intangible assets					$ 24,200,000

Intangible Assets - Schedule of Future Amortization Amounts During the Remaining Life (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total	$ 340,976	$ 568,292
Noncompete Agreements [Member]
2020	227,316
2021	113,660
Total	$ 340,976	$ 568,292	$ 795,608

Intangible Assets - Schedule of Fair Value of Assets Acquired (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible assets, beginning balance	$ 568,292
Impairment charge	2,400,000
Intangible assets, ending balance	340,976	$ 568,292
Noncompete Agreements [Member]
Intangible assets, beginning balance	568,292	795,608
Amortization	(227,316)	(227,316)
Impairment charge
Intangible assets, ending balance	340,976	568,292
IPR&D [Member]
Intangible assets, beginning balance	15,736,491	20,246,491
Amortization
Impairment charge		(4,510,000)
Intangible assets, ending balance	15,736,491	15,736,491
Goodwill [Member]
Intangible assets, beginning balance	1,976,101	1,976,101
Amortization
Impairment charge
Intangible assets, ending balance	$ 1,976,101	$ 1,976,101

Property and Equipment - Summary of Property and Equipment (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Property and equipment gross	$ 3,502,044	$ 3,152,886
Less accumulated depreciation and amortization	(3,096,681)	(2,968,259)
Total	405,363	184,627
Machinery and Equipment [Member]
Property and equipment gross	2,831,564	2,596,170
Furniture and Fixtures [Member]
Property and equipment gross	327,278	267,712
Leasehold Improvements [Member]
Property and equipment gross	$ 343,202	$ 289,004

Property and Equipment - Summary of Property and Equipment (Details) (Parenthetical)	12 Months Ended
	Dec. 31, 2019
Machinery and Equipment [Member] \| Minimum [Member]
Estimated useful life	5 years
Machinery and Equipment [Member] \| Maximum [Member]
Estimated useful life	7 years
Furniture and Fixtures [Member] \| Minimum [Member]
Estimated useful life	3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Estimated useful life	5 years
Leasehold Improvements [Member] \| Minimum [Member]
Estimated useful life	5 years
Leasehold Improvements [Member] \| Maximum [Member]
Estimated useful life	7 years

Other Accrued Liabilities - Schedule of Other Accrued Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Amounts due to contract research organizations and other contractual agreements	$ 475,440	$ 749,369
Accrued payroll and related benefits	1,604,541	1,592,590
Accrued professional fees	204,155	198,654
Other	19,411	45,285
Total	$ 2,303,547	$ 2,585,898

Note Payable (Details Narrative) - USD ($)		12 Months Ended
Note Payable (Details Narrative) - USD ($)	Jun. 27, 2018	Dec. 31, 2019	Dec. 31, 2018
Warrant exercise price		$ 0.01
Financing fees and expenses		$ 1,393,400	$ 712,025
Horizon Credit Agreement [Member]
Debt effective interest rate		9.63%
Interest expense, debt, total		$ 1,006,760	512,872
Amortization of debt issuance costs		$ 386,640	$ 199,153
Horizon Credit Agreement [Member] \| Horizon Warrants [Member]
Class of warrant or right exercisable	190,114
Warrant exercise price	$ 2.63
Debt instrument, unamortized discount, total	$ 507,116
Horizon Credit Agreement [Member] \| LIBOR plus [Member]
Interest rate	7.625%
Horizon Credit Agreement [Member]
Line of credit facility, maximum borrowing capacity	$ 10,000,000
Proceeds from lines of credit, total	$ 10,000,000
Percentage of outstanding principle balance, description	An amount equal to 1-3%
Debt instrument, unamortized discount, total	$ 782,116
Financing fees and expenses	175,000
Loan origination fees	$ 100,000
Percentage for original debt, amount	4.00%
Interest expense, debt, total	$ 400,000

Note Payable - Schedule of Future Principle Payments, Net of Unamortized Debt Discounts (Details)	Dec. 31, 2019 USD ($)
Debt Disclosure [Abstract]
2020	$ 2,083,334
2021	4,583,333
2022	3,333,333
2023 and thereafter
Subtotal of future principal payments	10,000,000
Unamortized debt issuance costs, net	(196,323)
Total	$ 9,803,677

Income Taxes (Details Narrative) - USD ($)	1 Months Ended		3 Months Ended	5 Months Ended			11 Months Ended	12 Months Ended		20 Months Ended	25 Months Ended
Income Taxes (Details Narrative) - USD ($)	Dec. 31, 2018	Jul. 31, 2011	Mar. 31, 2020	Oct. 31, 2017	Jun. 30, 2017	Jun. 30, 2013	Aug. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2013	Feb. 28, 2017	Jun. 30, 2015
Income tax, description								The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018.
Income tax, u.s. Corporate income tax rate								21.00%	21.00%
Deferred tax asset								$ 1,819,324
Net operating losses		$ 4,200,000		$ 800,000	$ 300,000	$ 1,500,000	$ 1,500,000	289,000,000		$ 1,400,000	$ 300,000	$ 1,600,000
Net operating losses, unused								$ 247,000,000
Net operating losses expiration, description								Expire starting in 2023 through 2037
Net operating losses carryforward limits, description								The deduction for net operating losses incurred in tax years beginning after January 1, 2018 is limited to 80% of annual taxable income
Operating loss carry forwards, limitation on use								The Company determined that it experienced ownership changes, as defined by Section 382, in connection with certain common stock offerings in July 2011, February 2013, June 2013, June 2015, February 2017, June 2017, October 2017 and August 2018. As a result, the utilization of the Company's federal tax net operating loss carry forwards generated prior to the ownership changes are limited. As of December 31, 2018, the Company has net operating loss carry forwards for U.S. federal and state tax purposes of approximately $233 million, before excluding net operating losses that have been limited as a result of Section 382 limitations. The annual limitation due to Section 382 for net operating loss carry forward utilization is approximately $4.2 million per year for approximately $90 million in net operating loss carry forwards existing at the ownership change occurring in July 2011, approximately $1.4 million per year for approximately $34 million of additional net operating losses occurring from July 2011 to the ownership change that occurred in February 2013, approximately $1.5 million per year for approximately $4 million of additional net operating losses occurring from February 2013 to the ownership change that occurred in June 2013, approximately $1.6 million per year for approximately $40 million of additional net operating losses occurring from June 2013 to the ownership change that occurred in June 2015, approximately $0.3 million per year for approximately $35 million of additional net operating losses occurring from June 2015 to the ownership change that occurred in February 2017, approximately $0.3 million per year for approximately $7 million of additional net operating losses occurring from February 2017 to the ownership change that occurred in June 2017, approximately $0.8 million per year for approximately $5 million of additional net operating losses occurring from June 2017 to the ownership change that occurred in October 2017, and approximately $1.5 million per year for approximately $30 million of additional net operating losses occurring from October 2017 to the ownership change that occurred in August 2018. The utilization of these net operating loss carry forwards may be further limited if the Company experiences future ownership changes as defined in Section 382 of the Internal Revenue Code.
Operating loss carry forwards, limitation on use		$ 90,000,000		$ 5,000,000	$ 7,000,000	$ 4,000,000	$ 30,000,000			$ 34,000,000	$ 35,000,000	$ 40,000,000
New Jersey [Member]
Deferred tax asset								$ 1,800,000
Proceeds from sale of nols	10,400,000								11,100,000
Future tax benefits remaining under the nol program									2,100,000
New Jersey [Member] \| Subsequent Event [Member]
Payments from sale of nols			$ 1,800,000
Federal Income Tax [Member]
Net operating losses	25,800,000								25,800,000
U.S. Federal and State Tax [Member]
Net operating losses	$ 233,000,000								$ 233,000,000

Income Taxes - Schedule of Income Tax Provision (Benefit) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal, Current
Federal, Deferred
State and Local, Current		(10,419,115)
State and Local, Deferred	(1,819,324)
Effective tax rate	$ (1,816,474)	$ (10,419,115)

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%
State taxes, net of federal tax benefit	12.20%	36.90%
Permanent differences	(4.50%)	(3.80%)
Other	(7.00%)	(9.40%)
Change in valuation allowance and deferred rate change, net	(12.00%)	2.00%
Effective tax rate	9.70%	46.70%

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 58,243,000	$ 51,498,000
Other Deferred tax assets, net	254,283	1,092,000
Subtotal	58,497,283	52,590,000
Valuation allowance	(56,497,283)	(52,590,000)
Total deferred tax asset	$ 1,819,324

Stockholders' Equity (Details Narrative) - USD ($)						1 Months Ended	2 Months Ended	12 Months Ended		68 Months Ended
Stockholders' Equity (Details Narrative) - USD ($)	Feb. 27, 2020	Oct. 28, 2019	Dec. 04, 2018	Aug. 31, 2018	Feb. 01, 2013	Sep. 30, 2018	Mar. 05, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 12, 2020
Shelf registration statement amount						$ 75,000,000
Fair value of common stock issued as equity issuance costs and charged against paid in capital									$ 450,000
Proceeds from issuance of common stock								$ 7,844,852	$ 858,515
Warrants exercise price								$ 0.01
2018 Aspire Purchase Agreements [Member]
Fair value of common stock issued as equity issuance costs and charged against paid in capital						$ 450,000
2018 Aspire Purchase Agreements [Member]
Aggregate offering price, additions				$ 15,000,000
Aggregate offering price, term				24 months
Maximum number of shares purchased per business day				100,000
Aggregate offering price				$ 15,000,000
Aggregate offering price, description				The lowest sale price of the Company's common stock on the purchase date; or the arithmetic average of the three (3) lowest closing sale prices for the Company's common stock during the ten (10) consecutive trading days ending on the trading day immediately preceding the purchase date.
Aspire purchase agreement, terms				In addition, on any date on which the Company submits a Purchase Notice to Aspire Capital in an amount equal to at least 100,000 shares, the Company also has the right, in its sole discretion, to present Aspire Capital with a volume-weighted average price purchase notice (each, a "VWAP Purchase Notice") directing Aspire Capital to purchase an amount of stock equal to up to 30% of the aggregate shares of the Company's common stock traded on its principal market on the next trading day (the "VWAP Purchase Date"), subject to a maximum number of shares the Company may determine. The purchase price per share pursuant to such VWAP Purchase Notice is generally 97% of the volume-weighted average price for the Company's common stock traded on its principal market on the VWAP Purchase Date.
Maximum number of shares purchased per business day, additional				2,000,000
Stock issued during period, shares, new issues				164,835				3,300,000	100,000
Proceeds from issuance of common stock								$ 6,300,000	$ 200,000
2019 Aspire Purchase Agreements [Member]
Aggregate offering price, additions		$ 10,000,000
Aggregate offering price, term		24 months
Maximum number of shares purchased per business day		100,000
Aggregate offering price		$ 10,000,000
Aggregate offering price, description		The lowest sale price of the Company's common stock on the purchase date; or the arithmetic average of the three (3) lowest closing sale prices for the Company's common stock during the ten (10) consecutive trading days ending on the trading day immediately preceding the purchase date.
Aspire purchase agreement, terms		In addition, on any date on which the Company submits a Purchase Notice to Aspire Capital in an amount of 100,000 shares, the Company also has the right, in its sole discretion, to present Aspire Capital with a VWAP Purchase Notice directing Aspire Capital to purchase an amount of stock equal to up to 30% of the aggregate shares of the Company's common stock traded on the VWAP Purchase Date, subject to a maximum number of shares the Company may determine. The purchase price per share pursuant to such VWAP Purchase Notice is generally 97% of the volume-weighted average price for the Company's common stock traded on its principal market on the VWAP Purchase Date.
Stock issued during period, shares, new issues		100,000						500,000
Proceeds from issuance of common stock								$ 700,000
2019 Aspire Purchase Agreements [Member] \| Subsequent Event [Member]
Stock issued during period, shares, new issues							1,000,000
Proceeds from issuance of common stock							$ 1,600,000
Capital on DemandTM Sales Agreement [Member]
Aggregate offering price			$ 16,000,000
Aggregate offering price, description			(i) the sale of all shares of our common stock subject to the Sales Agreement, and (ii) the termination of the Capital on Demand Agreement by JonesTrading or Celsion. The Capital on Demand Agreement may be terminated by JonesTrading or the Company at any time upon 10 days' notice to the other party, or by JonesTrading at any time in certain circumstances, including the occurrence of a material adverse change in the Company.
Commission percentage for gross proceeds from common stock			3.00%
Capital on Demand Agreement [Member]
Stock issued during period, shares, new issues								500,000
Proceeds from issuance of common stock								$ 1,000,000
Aggregate value available for issuance								$ 15,000,000
Controlled Equity Offering SM Sales Agreement [Member]
Aggregate offering price					$ 25,000,000
Stock issued during period, shares, new issues										1,784,396
Proceeds from issuance of common stock										$ 12,800,000
Proceeds from sale equity									$ 1,200,000
Sale of common stock, shares									500,000
Securities Purchase Agreement [Member] \| Subsequent Event [Member]
Stock issued during period, shares, new issues	4,571,428
Proceeds from issuance of common stock	$ 4,800,000
Shares issued, price per share	$ 1.05
Securities Purchase Agreement [Member] \| Subsequent Event [Member] \| Original Warrants [Member]
Number of warrants to purchase common stock	2,971,428
Warrants term	5 years
Warrants exercise price	$ 1.15
Private Exchange Agreements [Member] \| Subsequent Event [Member] \| Warrant [Member]
Number of warrants to purchase common stock											3,200,000
Warrants term											5 years
Warrants exercise price											$ 1.24

Stock-Based Compensation (Details Narrative) - USD ($)			12 Months Ended
Stock-Based Compensation (Details Narrative) - USD ($)	Feb. 19, 2019	Sep. 28, 2018	Dec. 31, 2019	Dec. 31, 2018
Unrecognized compensation cost related to non-vested stock based compensation			$ 1,600,000
Stock based compensation cost expected to be recognized, weighted average period			1 year 1 month 6 days
Research and Development Expense [Member]
Compensation cost			$ 900,000	$ 1,500,000
General and Administrative Expense [Member]
Compensation cost			1,400,000	3,100,000
Restricted Stock Awards [Member]
Compensation cost			$ 4,600,000	$ 4,600,000
Equity Stock Awards [Member]
Number of shares reserved for future issuance			4,130,886
Inducement Awards [Member]
Number of shares reserved for future issuance			210,006
Stock Options [Member]
Inducement option grant, exercise price per share			$ 2.00	$ 2.26
Compensation cost			$ 2,300,000	$ 2,300,000
2018 Stock Incentive Plan [Member]
Equity awards, number of stock authorized			2,700,000
Percentage of fair market value of shares			100.00%
Percentage of outstanding stock determining factor for incentive stock price			10.00%
Number of shares reserved for future issuance			4,580,893
2018 Stock Incentive Plan [Member] \| Minimum [Member]
Number of equity awards available for future issuance			1,200,000
Percentage of fair market value of shares			110.00%
2018 Stock Incentive Plan [Member] \| Maximum [Member]
Number of equity awards available for future issuance			3,900,000
Inducement Option Grants [Member] \| Five New Employees [Member]
Inducement option grant, exercise price per share	$ 2.18	$ 2.77
Option vested period	3 years	3 years
Options expiration period	10 years	10 years
Inducement Option Grants [Member] \| Five New Employees [Member] \| Restricted Stock Awards [Member]
Number of shares issued	13,000	19,000
Inducement Option Grants [Member] \| Five New Employees [Member] \| Common Stock [Member]
Number of shares issued	140,004	164,004
2007 Stock Incentive Plan [Member]
Number of shares reserved for future issuance			450,007

Stock-Based Compensation - Summary of Stock Option Awards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number Outstanding, Ending Balance	3,885,892
Number Outstanding, Exercisable	2,469,033
Stock Options [Member]
Number Outstanding, Outstanding, Beginning Balance	3,148,743	703,442
Number Outstanding, Granted	1,250,754	2,629,004
Number Outstanding, Cancelled or expired	(67,355)	(183,703)
Number Outstanding, Ending Balance	4,332,142	3,148,743
Number Outstanding, Exercisable	2,469,033
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 2.67	$ 10.34
Weighted Average Exercise Price, Granted	2.00	2.26
Weighted Average Exercise Price, Cancelled or expired	2.50	25.96
Weighted Average Exercise Price, Outstanding, Ending Balance	2.63	$ 2.67
Weighted Average Exercise Price, Exercisable	$ 2.98
Weighted Average Remaining Contractual Term (years), Outstanding, Ending Balance	8 years 6 months
Weighted Average Remaining Contractual Term (years), Exercisable	8 years
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 5,882
Aggregate Intrinsic Value, Exercisable

Stock-Based Compensation - Summary of Non-vested Restricted Stock Awards (Details) - Restricted Stock Awards [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number Outstanding, Non-vested stock awards outstanding, Beginning Balance	22,500
Number Outstanding, Non-vested stock awards outstanding, Granted	29,250	35,000
Number Outstanding, Non-vested stock awards outstanding, Vested and issued	(5,000)	(6,000)
Number Outstanding, Non-vested stock awards outstanding, Forfeited	(38,000)	(6,500)
Number Outstanding, Non-vested stock awards outstanding, Ending Balance	8,750	22,500
Weighted Average Grant Date Fair Value, Beginning Balance	$ 2.72
Weighted Average Grant Date Fair Value, Granted	1.99	2.71
Weighted Average Grant Date Fair Value, Vested and issued	2.14	2.77
Weighted Average Grant Date Fair Value, Forfeited	2.48	2.64
Weighted Average Grant Date Fair Value, Ending Balance	$ 1.59	$ 2.72

Stock-Based Compensation - Summary of Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Options Outstanding, Number \| shares	3,885,892
Options Exercisable, Number \| shares	2,469,033
Exercise Price One [Member]
Range of Exercise Prices, Upper	$ 5.00
Options Outstanding, Number \| shares	3,821,470
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	8 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 2.47
Options Exercisable, Number \| shares	2,404,611
Options Exercisable, Weighted Average Remaining Contractual Term (in years)	8 years
Options Exercisable, Weighted Average Exercise Price	$ 2.55
Exercise Price Two [Member]
Range of Exercise Prices, Upper	81.90
Range of Exercise Prices, Lower	$ 5.00
Options Outstanding, Number \| shares	64,422
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years
Options Outstanding, Weighted Average Exercise Price	$ 19.00
Options Exercisable, Number \| shares	64,422
Options Exercisable, Weighted Average Remaining Contractual Term (in years)	6 years
Options Exercisable, Weighted Average Exercise Price	$ 19.00

Stock-Based Compensation - Schedule of Assumptions Used to Determine Fair Value of Options Granted (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Risk-free interest rate, minimum	2.82%	2.82%
Risk-free interest rate, maximum	3.02%	3.02%
Expected volatility, minimum	101.30%	99.90%
Expected volatility, maximum	106.20%	102.10%
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Expected life (in years)	7 years 6 months	8 years 6 months
Maximum [Member]
Expected life (in years)	9 years 3 months 19 days	10 years

Earn-out Milestone Liability (Details Narrative) - USD ($)			3 Months Ended	12 Months Ended
	Jun. 20, 2014	Jun. 20, 2014	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 28, 2019	Sep. 30, 2018
Fair value of acquisition consideration					$ 4,500,000	$ 2,500,000
Warrants to purchase common stock				1,167,064	13,927
Warrant exercise price				$ 0.01
Gain (loss) from change in fair value of earn out milestone liability				$ (3,189,955)	$ (3,630,861)
EGEN Inc [Member]
Future earn-out payments	$ 30,400,000	$ 30,400,000
Fair value of acquisition consideration	$ 13,900,000
Risk adjusted assessment of each milestone					80.00%
Estimated time to achieve the milestone					1 year 2 months 30 days
Warrants to purchase common stock								200,000
Warrants strike price								$ 0.01
Warrant exercise price								$ 2.00
EGEN Inc [Member] \| Amended Asset Purchase Agreement [Member]
Earnout milestone liability							$ 12,400,000
EGEN Inc [Member] \| Amended Asset Purchase Agreement [Member] \| 10 Business Days of Achieving Milestone [Member]
Earnout milestone liability							7,000,000
EGEN Inc [Member] \| Amended Asset Purchase Agreement [Member] \| Within One Year of Achieving Milestone [Member]
Earnout milestone liability							$ 12,400,000
EGEN Inc [Member] \| Fair Value Earnout Milestone Liability [Member]
Fair value of acquisition consideration				6,200,000	$ 8,900,000	$ 12,500,000
Gain on non-cash benefit				$ 2,700,000	$ 3,600,000
Gain (loss) from change in fair value of earn out milestone liability			$ 3,900,000
EGEN Inc [Member] \| Amended Asset Purchase Agreement Option Payment 1 [Member]
Risk adjusted assessment of each milestone				665.00%
Gain (loss) from change in fair value of earn out milestone liability				$ 7,000,000
EGEN Inc [Member] \| Amended Asset Purchase Agreement Option Payment 2 [Member]
Risk adjusted assessment of each milestone				35.00%
Gain (loss) from change in fair value of earn out milestone liability				$ 12,400,000
EGEN Inc [Member] \| Minimum [Member]
Risk adjusted assessment of each milestone	10.00%	10.00%
Estimated time to achieve the milestone	1 year 6 months
EGEN Inc [Member] \| Maximum [Member]
Risk adjusted assessment of each milestone	67.00%	67.00%
Estimated time to achieve the milestone		2 years 6 months

Earn-out Milestone Liability - Schedule of Changes in Earn-out Milestone Liability (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Hercules Warrant [Member]
Earn-out liabilities, beginning balance	$ 8,907,664	$ 12,538,525
Non-cash gain from the adjustment for the change in fair value included in net loss	(3,189,955)	(3,630,861)
Earn-out liabilities, ending balance	$ 5,117,709	$ 8,907,664

Warrants (Details Narrative) - shares	12 Months Ended
Warrants (Details Narrative) - shares	Dec. 31, 2018	Dec. 31, 2019
Number of shares, warrant rights	13,927	1,167,064
Warrant Exchange Agreements [Member]
Common stock shares issued	820,714
Investor [Member]
Number of shares, warrant rights	1,600,000

Warrants - Summary of Warrant Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Warrants and Rights Note Disclosure [Abstract]
Number of Warrants Issued, Warrants Outstanding, Beginning Balance	1,593,162	3,058,402
Number of Warrants Issued, Warrants Issued	200,000	190,114
Number of Warrants Issued, Warrants cancelled in exchange for common stock		(1,641,427)
Number of Warrants Issued, Warrants Expired	(1,167,064)	(13,927)
Number of Warrants Issued, Warrants Outstanding, Ending Balance	626,098	1,593,162
Weighted Average Exercise Price, Warrants Outstanding, Beginning Balance	$ 5.36	$ 5.29
Weighted Average Exercise Price, Warrants Issued	0.01	2.63
Weighted Average Exercise Price, Warrants cancelled in exchange for common stock		3.04
Weighted Average Exercise Price, Warrants Expired	6.32	226.24
Weighted Average Exercise Price, Warrants Outstanding and Exercisable, Ending Balance	$ 1.87	$ 5.36
Aggregate Intrinsic Value of Outstanding Warrants	$ 340,000
Weighted average remaining contractual terms (years)	1 year 10 months 14 days

Warrants - Schedule of Weighted Average Remaining Contractual Terms (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number of Warrants Issued	200,000	190,114
Number of Warrants Issued, Warrants Outstanding, Ending Balance	626,098	1,593,162
All Other Warrants [Member]
Weighted Average Exercise Price	$ 2.74
Weighted Average Contractual Terms Remaining (in years)	5 years 3 months 19 days
Number of Warrants Issued, Warrants Outstanding, Ending Balance	426,098
EGWU, Inc [Member]
Number of Warrants Issued	200,000
Weighted Average Exercise Price	$ 0.01
Weighted Average Contractual Terms Remaining (in years)	0 years

Celsion Employee Benefit Plans (Details Narrative) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Postemployment Benefits [Abstract]
Maximum annual contributions per employee, percent	3.00%
Matching contributions of employee	$ 105,999	$ 105,999
Discretionary contribution		$ 181,999
Discretionary contribution, rate		6.00%

Leases (Details Narrative)		1 Months Ended		12 Months Ended
Leases (Details Narrative)	Jan. 02, 2019 USD ($)	Jan. 31, 2018 USD ($) ft²	Jul. 31, 2011 ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lease description			In 2011, the Company executed a lease (the "Lease") with Brandywine Operating Partnership, L.P. (Brandywine), a Delaware limited partnership for a 10,870 square foot premises located in Lawrenceville, New Jersey and relocated its offices to Lawrenceville, New Jersey from Columbia, Maryland.
Area of land \| ft²			10,870
Lease, term of contract			66 months
Lease expiration date			Apr. 30, 2017
Lease, renewal term			64 months
Lease, option to extend				The 1st Lease Amendment extended the term of the agreement for an additional 64 months, reduced the premises to 7,565 square feet, reduced the monthly rent and provided four months free rent. The monthly rent ranged from approximately $18,900 in the first year to approximately $20,500 in the final year of the 1st Lease Amendment. The Company also had a one-time option to cancel the lease as of the 40th month after the commencement date of the 1st Lease Amendment and must provide the landlord notice by the 28th month of the lease. Effective January 9, 2019, the Company amended the current terms of the 1st Lease Amendment to increase the size of the premises by 2,285 square feet to 9,850 square feet and also extended the lease term by one year to September 1, 2023. In conjunction with this 2nd Lease Amendment, we agreed to modify our one-time option to cancel the lease as of the end of August 2021 and we must provide notice to the landlord by the end of August 2020. The monthly rent will range from approximately $25,035 in the first year to approximately $27,088 in the final year of the 2nd Lease Amendment.
ROU asset	$ 400,000			$ 1,431,640
Operating lease liabilities	1,900,000			1,531,450
Other liabilities				100,000
Increased ROU asset	$ 1,800,000			1,797,561
Operating lease costs					450,430
Operating lease expense				485,848
Accounting Standards Update 2016-02 [Member]
ROU asset				1,400,000
Operating lease liabilities				1,500,000
Other liabilities				100,000
1st Lease Amendment [Member] \| First Year [Member]
Lease, rent payment				18,900
1st Lease Amendment [Member] \| Final Year [Member]
Lease, rent payment				20,500
2nd Lease Amendment [Member] \| First Year [Member]
Lease, rent payment				25,035
2nd Lease Amendment [Member] \| Final Year [Member]
Lease, rent payment				27,088
EGEN Asset Purchase Agreement [Member]
Lease description		In connection with the EGEN Asset Purchase Agreement in June 2014, the Company assumed the existing lease with another landlord for an 11,500 square foot premises located in Huntsville Alabama. In January 2018, the Company and the Huntsville landlord entered into a new 60-month lease which reduced the premises to 9,049 square feet with rent payments of approximately $18,100 per month.
Area of land \| ft²		11,500
Lease, rent payment		$ 18,100
60 Month Lease [Member]
Area of land \| ft²		9,049
Operating Leases [Member]
Operating lease expense				522,380
Cash paid for operating leases, including operating cash flows				$ 457,321

Leases - Schedule of Lease Payments and Maturity of Our Operating Lease Liabilities (Details) - USD ($)	Dec. 31, 2019	Jan. 02, 2019
Leases [Abstract]
2020	$ 525,809
2021	530,734
2022	535,579
2023	233,117
2024 and thereafter
Subtotal future lease payments	1,825,239
Less imputed interest	(293,790)
Total lease liabilities	$ 1,531,450	$ 1,900,000
Weighted average remaining life	3 years 5 months 12 days
Weighted average discount rate	9.98%

Licenses of Intellectual Property and Patents (Details Narrative)	12 Months Ended
	Dec. 31, 2019 USD ($) Integer shares	Dec. 31, 2018 USD ($) shares	Jan. 31, 2003 USD ($) shares
Common stock, shares, issued \| shares	23,256,152	18,832,168
Common stock, value, issued \| $	$ 232,562	$ 188,322
Number of trademark protection application pending for thermo dox \| Integer	14
License Agreement [Member] \| Duke University [Member]
Number of days before issuance factoring into average closing price	20 days
Amount of time after effective date of license agreement for registration rights to take place	1 year
Common stock, shares, issued \| shares			253,691
Common stock, value, issued \| $			$ 2,200,000

Technology Development and Licensing Agreements (Details Narrative) - Hisun [Member]	Jan. 18, 2013 USD ($)
Non-refundable research and development fee	$ 5,000,000
Deferred revenue	$ 5,000,000
Deferred revenue amortization period	10 years

Subsequent Events (Details Narrative) - Subsequent Event [Member] - February 2020 Offering [Member]	Feb. 27, 2020 USD ($) shares
Sale of common stock, shares \| shares	4,600,000
Proceeds from offering \| $	$ 4,800,000