As filed with the Securities and Exchange Commission on July 17, 2020January 15, 2021

Registration No. 333-__________

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-3

REGISTRATION STATEMENT

UNDER THE SECURITIES ACT OF 1933

SOLIGENIX, INC.

(Exact name of registrant as specified in its charter)

Soligenix, Inc.

29 Emmons Drive, Suite B-10

Princeton, New Jersey 08540

(609) 538-8200

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive office)

Christopher J. Schaber, Ph.D.

President and Chief Executive Officer

Soligenix, Inc.

29 Emmons Drive, Suite B-10

Princeton, New Jersey 08540

(609) 538-8200

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Driscoll R. Ugarte, Esq.

Duane Morris LLP

1875 NW Corporate Boulevard

Suite 300

Boca Raton, Florida 33431-8561

(561) 962-2100

Approximate date of commencement of proposed sale to the public: from time to time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box: ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box: þ☑

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period to comply with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of Securities Act. ☐

CALCULATION OF REGISTRATION FEE

The registrantRegistrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrantRegistrant shall file a further amendment which specifically states that this Registration Statementregistration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act, of 1933, as amended, or until the registration statementRegistration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. Wechanged without notice. The selling stockholders may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it isthe selling stockholders named in this prospectus are not soliciting an offeroffers to buy these securities in any state or other jurisdiction where the offer or sale of these securities is not permitted.

Subject to completion, dated July 17, 2020January 15, 2021

PRELIMINARY PROSPECTUS

Soligenix, Inc.

$50,000,000

Up to 4,878,048 Shares of Common Stock Preferred Stock
Warrants and Units

This prospectus covers ourrelates to the offer and sale from timeby the selling stockholders identified in this prospectus, and any of their respective pledgees, donees, transferees, or other successors in interest, of up to time4,878,048 shares of common stock (“Common Stock”) of Soligenix, Inc. that are issuable pursuant to the terms of certain convertible notes due June 15, 2025 (the “Convertible Notes”), as further described in this prospectus.

The number of shares of Common Stock being registered hereunder is comprised of 4,878,048 shares of Common Stock issuable upon conversion of the Convertible Notes, which Convertible Notes are convertible into shares of our common stock, preferred stock, warrants to purchase common stock and/or preferred stock, and units in one or more offerings. The aggregate offeringCommon Stock at the lowest possible conversion price of all securities sold by us under this prospectus may not exceed $50 million.

This prospectus describes$4.10 per share (the “Conversion Shares”). The number of shares of Common Stock registered represents a good faith estimate of the number of shares of Common Stock which will be issued upon conversion of the Convertible Notes, assuming for purposes hereof, that the Convertible Notes will accrue interest through June 15, 2025 at a rate of 8.47% per annum and that we will pay interest amounts in cash quarterly through the maturity of the Convertible Notes. If the Convertible Notes convert after we have paid some of the general terms that may apply to an offeringprincipal balance on the Convertible Notes, the actual number of these securities and the general manner in which these securities may be offered. Each time we offer and sell these securities we will provide specific terms of such offering in a supplement to this prospectus. A prospectus supplement may also add, update or change information contained in this prospectus or in documents we have incorporated by reference into this prospectus and, accordingly,shares issuable to the extent inconsistent, information inselling stockholders upon conversion of the Convertible Notes, if any, could be materially less than 4,878,048 shares of Common Stock depending on the amount of principal and accrued but unpaid interest that is converted into shares of Common Stock at the time. This presentation is not intended to constitute an indication or incorporated by reference in this prospectus is superseded byprediction of the information indate on which the prospectus supplement and any other offering material related to such securities.selling stockholders will convert the Convertible Notes into Common Stock, if at all.

We may offer and sell these securities from time to time at fixed prices, at market prices or at negotiated prices, and such securities may be offered and sold to or through one or more underwriters, dealers or agents or directly to purchasers on a continuous or delayed basis. Without limitation of the foregoing, shares may be issued in connection with (i) the achievement of clinical development milestones under license or purchase agreements, such as the asset purchase agreement with Hy Biopharma Inc. pursuant to which we acquired assets related to the development of our synthetic hypericin product candidate for the treatment of cutaneous T-cell lymphoma (SGX301), (ii) strategic partnering and/or acquisition transactions involving the issuance of our securities as well as to meet long-term corporate objectives, and (iii) capital raising transactions through the sale of securities in the private and/or public equity markets to support a higher level of growth, respond to competitive pressures, develop new products and services and support new strategic partnership expenditures.

Theare filing of the registration statement of which this prospectus formsis a part at this time to fulfill contractual obligations to do so pursuant to a registration rights agreement, as further described in this prospectus. We will not receive any of the proceeds from the sale of the Common Stock by the selling stockholders.

The selling stockholders and their respective pledgees, donees, transferees, or other successors in interest may offer the shares of Common Stock in one or more transactions at fixed prices, at prevailing market prices at the time of sale, at varying prices determined at the time of sale, at negotiated prices, or in trading markets for our Common Stock. Additional information on the selling stockholders, and the times and manner in which they may offer and sell shares of our Common Stock under this prospectus, is primarily driven by our desire to have sufficient registered securities available for possible mergerprovided under “Selling stockholders” and acquisition activities and other corporate development objectives that may occur over the coming years. However, we have no present plans to engage“Plan of Distribution” in such activities.this prospectus.

Our common stockCommon Stock and our common stock warrants issued in connection with our December 2016 public offering are traded on The NASDAQ Capital Market under the symbols “SNGX” and “SNGXW,” respectively. On JulyJanuary 13, 2020,2021, the last reported closing sales prices of our common stockCommon Stock and our common stock warrants issued in connection with our 2016 public offering on The NASDAQ Capital Market were $1.91$1.40 per share and $0.50$0.186 per warrant.

As of July 13, 2020, the aggregate market value of our outstanding common stock held by non-affiliates was $55,306,867, which was calculated based on 28,956,475 shares of outstanding common stock held by non-affiliates and on a price per share of $1.91. Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell the shelf securities in a public primary offering with a value exceeding more than one-third of the aggregate market value of our voting and non-voting common equity held by non-affiliates in any 12-month period as long as the aggregate market value of our outstanding voting and non-voting common equity held by non-affiliates is less than $75 million. During the 12 calendar months prior to and including the date of this prospectus, we have not offered or sold any securities pursuant to General Instruction I.B.6 of Form S-3.

INVESTING IN OUR SECURITIESCOMMON STOCK INVOLVES A HIGH DEGREECERTAIN RISKS. SEE “RISK FACTORS” BEGINNING ON PAGE 3 OF RISK.THIS PROSPECTUS FOR THE RISKS THAT YOU SHOULD REVIEWCONSIDER. YOU SHOULD READ THIS ENTIRE PROSPECTUS CAREFULLY THE RISKS AND UNCERTAINTIES DESCRIBED UNDER THE HEADING “RISK FACTORS” CONTAINED IN THE APPLICABLE PROSPECTUS SUPPLEMENT WE HAVE AUTHORIZED FOR USE IN CONNECTION WITH A SPECIFIC OFFERING, AND UNDER SIMILAR HEADINGS IN THE DOCUMENTS THAT ARE INCORPORATED BY REFERENCE INTO THIS PROSPECTUS.BEFORE YOU MAKE YOUR INVESTMENT DECISION.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS MAY NOT BE USEDIS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO CONSUMMATETHE CONTRARY IS A SALE OF ANY SECURITIES UNLESS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.CRIMINAL OFFENSE.

The date of this prospectus is July 17, 2020.____________, 2021.

TABLE OF CONTENTS

About This Prospectus

This prospectus is part of a registration statement that we filed with the United States Securities and Exchange Commission (the “SEC”), using a “shelf” registration process. Under this shelf registration process, we may, from time to time, offer and sell, either separately or together, any combination of the securities described in this prospectus in one or more offerings for cash. We may also issue any of the common stock, preferred stock, warrants, or units upon conversion, exchange or exercise of any of the securities mentioned above. The aggregate amount of securities that we may offer under the registration statement is $50 million, denominated in U.S. dollars or the equivalent in foreign currencies, currency units or composite currencies. We are subject to the provisions of General Instruction I.B.6. of the General Instructions to Form S-3, which provide that as long as the aggregate market value of our outstanding voting and non-voting common equity held by non-affiliates of our company is less than $75 million, then the aggregate market value of securities sold by us or on our behalf on Form S-3, during the period of 12 calendar months immediately prior to, and including, the sale, is no more than one-third of the aggregate market value of the voting and non-voting common equity held by non-affiliates of our company. We have no outstanding non-voting common equity.

This prospectus describes some of the general terms that may apply to an offering of our securities and the general manner in which they may be offered. Each time we sell any securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus or in documents we have incorporated by reference into this prospectus and, accordingly, to the extent inconsistent, information in or incorporated by reference in this prospectus is superseded by the information in the prospectus supplement and any other offering material related to such securities.

This prospectus may not be used to sell any securities unless accompanied by a prospectus supplement. You should carefully read this prospectus, the applicable prospectus supplement, the information and documents incorporated herein by reference and the additional information described under the heading “Where You Can Find Additional Information” in this prospectus, before you invest in any of the securities offered hereunder.

You should rely only on the information contained in this prospectus or any accompanying prospectus supplement to this prospectus. We have not authorized anyone to provide you with any information other than that contained in this prospectus and any accompanying prospectus supplement to this prospectus. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus and any accompanying supplement to this prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus and any accompanying supplement to this prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.

For investors outside the United States: We have not done anything that would permit this offering or possession or distribution of this prospectus or any accompanying prospectus supplement to this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus or any accompanying prospectus supplement to this prospectus must inform themselves about, and observe any restrictions relating to, the offering of securities and the distribution of this prospectus outside the United States.

As used in this prospectus, the terms “we,” “us,” “our” and “our company” mean Soligenix, Inc., unless the context clearly indicates otherwise.

WhereYou should rely only on the information contained or incorporated by reference in this prospectus. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. For further information, please see the section of this prospectus titled “Where You Can Find More InformationInformation.” The selling stockholders are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

We file annual, quarterlyYou should not assume that the information appearing in this prospectus is accurate as of any date other than the date on the front cover of this prospectus, regardless of the time of delivery of this prospectus or any sale of a security. Our business, financial condition, results of operations, and current reports, proxy statements and other information with the SEC. The SEC maintains an internet site that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC, including us, at http://www.sec.gov. Our internet address is www.soligenix.com.prospects may have changed since those dates.

This prospectus contains trademarks, tradenames, service marks, and service names of the Company.

Incorporation of Information by Reference

The SEC allows us to “incorporate by reference” into this prospectus the information we file with the SEC, which means that we can disclose important information to you by referring you to those documents. Any information referenced this way is considered to be part of this prospectus, and any information that we file later with the SEC will automatically update and, where applicable, supersede this information. We incorporate by reference the following documents that we have filed with the SEC (other than, in each case, documents or information deemed to have been furnished and not filed in accordance with the SEC’s rules):

We also incorporate by reference into this prospectus additional documents that we may file with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), on or after the date of this prospectus and prior to the completion or termination of the offering of the securities described in this prospectus, including all such documents filed by us pursuant to the Exchange Act after the date of the initial registration statement and prior to the effectiveness of the registration statement, but excluding any information deemed furnished and not filed with the SEC.

Any statement contained in a document incorporated or deemed to be incorporated herein by reference shall be deemed to be modified or superseded to the extent that a statement contained herein, or in a subsequently filed document also incorporated or deemed to be incorporated herein by reference, modifies or supersedes such statement in such document. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this registration statement.

This prospectus is part of a registration statement on Form S-3 we have filed with the SEC relating to the securities. As permitted by SEC rules, this prospectus does not contain all of the information included in the registration statement and the accompanying exhibits and schedules we file with the SEC. We have filed or incorporated by reference certain legal documents that control the terms of the shares of common stock and preferred stock offered under this prospectus as exhibits to the registration statement. We may file certain other legal documents that control the terms of the shares of common stock and preferred stock offered by this prospectus as exhibits to reports we file with the SEC. You may refer to the registration statement and the exhibits and schedules thereto for more information about us and our securities. The registration statement and exhibits and schedules are also available at the SEC’s internet site at http://www.sec.gov.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, a copy of any or all of the reports or documents that we incorporate by reference in this prospectus contained in the registration statement (except exhibits to the documents that are not specifically incorporated by reference) at no cost to you, by writing or calling us at: Soligenix, Inc., 29 Emmons Drive, Suite B-10, Princeton, New Jersey 08540, Attn: Secretary, telephone number: 609-538-8200. Information about us is also available at our website at www.soligenix.com. Except for the specific incorporated reports and documents listed above, no information available on or through our website shall be deemed to be incorporated in this prospectus or the registration statement of which it forms a part.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS AND INDUSTRY DATA

AND MARKET INFORMATION

This prospectus, any accompanying prospectus supplement and the information incorporated herein and therein by reference contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act.Act of 1934, as amended (the “Exchange Act”). These forward-looking statements are often identified by words such as “may,” “should,” “would,” “expect,” “intend,” “anticipate,” “believe,” “estimate,” “continue,” “plan,” “potential” and similar expressions. These statements involve estimates, assumptions and uncertainties that could cause actual results to differ materially from those expressed for the reasons described in this prospectus and in the documents incorporated herein by reference. You should not place undue reliance on these forward-looking statements.

We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. You should be aware that our actual results could differ materially from those contained in the forward-looking statements due to a number of factors, including:

You should also consider carefully the statements under the section titled “Risk Factors” in this prospectus, and documents incorporated herein by reference including the sections titled “Business,” “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” incorporated by reference from our most recent Annual Report on Form 10-K and in our Quarterly Reports on Form 10-Q, as well as any amendments thereto, filed with the SEC,United States Securities and Exchange Commission (the “SEC”), which address additional factors that could cause our actual results to differ from those set forth in the forward-looking statements and could materially and adversely affect our business, operating results and financial condition. All subsequent written and oral forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the applicable cautionary statements.

The forward-looking statements speak only as of the date on which they are made, and, except to the extent required by federal securities laws, we undertake no obligation to update any forward-looking statement to reflect events or circumstances after the date on which the statement is made or to reflect the occurrence of unanticipated events. In addition, we cannot assess the impact of each factor on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements.

Industry Data and Market Information

This prospectus, any accompanying prospectus supplement and the documents incorporated herein by reference contain estimates, projections and other statistical data made by independent parties and by us relating to market size and growth, the potential value of government procurement contracts, the incidence of certain medical conditions and other industry data. These data, to the extent they contain estimates or projections, involve a number of subjective assumptions and limitations, and you are cautioned not to give undue weight to such estimates or projections. Industry publications and other reports we have obtained from independent parties generally state that the data contained in these publications or other reports have been obtained in good faith or from sources considered to be reliable, but they do not guarantee the accuracy or completeness of such data. While we believe that the data from these industry publications and other reports are generally reliable, we have not independently verified the accuracy or completeness of such data. These and other factors could cause results to differ materially from those expressed in these publications and reports.

We have provided estimates of the potential worldwide market or value of potential government procurement contracts and grants for certain of our product candidates. These estimates are based on a number of factors, including our expectation as to the number of patients with a certain medical condition that would potentially benefit from a particular product candidate, the current costs of treating patients with the targeted medical condition, our expectation that we will be able to demonstrate to the FDA’s satisfaction in our clinical trials that the product candidate is safe and effective, our belief that our product candidate would, if approved, have an assumed treatment cost per patient, historic values of government procurement contracts for vaccines, and our expectation of the dosage of the product candidate. While we have determined these estimates based on assumptions that we believe are reasonable, there are a number of factors that could cause our expectations to change or not be realized. Among these factors are the following: (1) there is no assurance that the product candidate will prove to be safe and effective or will ultimately be approved for sale by the FDA; (2) any FDA approval of the product candidate may contain restrictions on its use or require warning labels; (3) third party payors may not be willing to provide reimbursement for the product candidate at the assumed price per patient; (4) the government may not be willing to procure our vaccine candidates in amounts or at costs similar to its historic procurement activities; (5) the dosage that ultimately may be approved may be different from the assumed dosage; and (6) doctors may not adopt the product candidate for use as quickly or as broadly as we have assumed. It is possible that the ultimate market for a product candidate or value of procurement contracts will differ significantly from our expectations due to these or other factors. As a result of these and other factors, investors should not place undue reliance on such estimates.

Risk Factors

Investing in our common stockCommon Stock involves a high degree of risk. Before making an investment decision, you should carefully consider the risks and uncertainties set forth in the “Risk Factors” section of our most recent Annual Report on Form 10-K, as revised or supplemented by our Quarterly Reports on Form 10-Q filed with the SEC since the filing of our most recent Annual Report on Form 10-K, each of which is incorporated by reference into this prospectus, and you should also carefully consider any other information we include or incorporate by reference in this prospectus or include in any applicable prospectus supplement, including our financial statements and the related notes thereto. The risks and uncertainties described in our filings with the SEC and incorporated by reference into this prospectus are not the only ones we face. Additional risks and uncertainties not presently known to us, or that we currently believe are not material, also may become important factors that affect us and impair our business operations. The occurrence of any of the events or developments discussed in the risk factors described in our filings with the SEC could have a material and adverse impact on our business, results of operations, financial condition and cash flows, and in such case, our future prospects would likely be materially and adversely affected. If any of such events or developments were to happen, you could lose part or all of your investment. Further, our actual results could differ materially and adversely from those anticipated in our forward-looking statements as a result of certain factors.

UseSummary of ProceedsRisk Factors

Our business is subject to a number of risks and uncertainties that you should understand before making an investment decision. These risks include, but are not limited to, the following:

Risks Related to our Business

Risks Related to our Intellectual Property

Risks Related to our Securities

The terms of our loan and security agreement with Pontifax Medison Finance require us to meet certain operating covenants and place restrictions on our operating and financial flexibility. If we raise additional capital through debt financing, the terms of any new debt could further restrict our ability to operate our business.

Unless otherwise indicatedIn December 2020, we entered into a loan and security agreement with certain of the selling stockholders (the “Loan and Security Agreement”), that is secured by a lien covering substantially all of our assets, other than our intellectual property and licenses for intellectual property. The Loan and Security Agreement contains customary affirmative and negative covenants and events of default. Affirmative covenants include, among others, covenants requiring us to protect and maintain our intellectual property and comply with all applicable laws, deliver certain financial reports, maintain a minimum cash balance and maintain insurance coverage. Negative covenants include, among others, covenants restricting us from transferring any material portion of our assets, incurring additional indebtedness, engaging in a prospectus supplementmergers or acquisitions, changing foreign subsidiary voting rights, repurchasing shares, paying dividends or making other distributions, making certain investments, and creating other liens on our assets, including our intellectual property, in each case subject to customary exceptions. If we raise any free writing prospectuses we have authorized for use in connection with a specific offering, we anticipate thatadditional debt financing, the net proceeds fromterms of such additional debt could further restrict our sale of any securities offered hereunder, if any, will be used for general corporate purposes, whichoperating and financial flexibility. These restrictions may include, among other things, workinglimitations on borrowing and specific restrictions on the use of our assets, as well as prohibitions on our ability to create liens, pay dividends, redeem capital product development, acquisitions, capital expenditures,stock or make investments. If we default under the terms of the Loan and Security Agreement or any future debt facility, the lender may accelerate all of our repayment obligations and take control of debtour pledged assets, potentially requiring us to renegotiate our agreement on terms less favorable to us or to immediately cease operations. Further, if we are liquidated, the lender’s right to repayment would be senior to the rights of the holders of our Common Stock. The lender could declare a default upon the occurrence of any event that it interprets as a material adverse effect as defined under the Loan and Security Agreement. Any declaration by the lender of an event of default could significantly harm our business and prospects and could cause the price of our Common Stock to decline.

Repayment of the Convertible Notes, if they are not otherwise converted, will require a significant amount of cash, and we may not have sufficient cash flow from our business to make payments on our indebtedness.

Our ability to pay the principal of and/or interest on the Convertible Notes depends on our future performance, which is subject to economic, financial, competitive and other factors beyond our control. Our business opportunities.may not generate cash flow from operations in the future sufficient to service the Convertible Notes or other future indebtedness and make necessary capital expenditures. If we are unable to generate such cash flow, we may be required to adopt and implement one or more alternatives, such as selling assets, restructuring indebtedness or obtaining additional debt financing or equity financing on terms that may be onerous or highly dilutive. Our ability to refinance the Convertible Notes or other future indebtedness will depend on the capital markets and our financial condition at such time. We may not be able to engage in any of these activities or engage in these activities on desirable terms, which could result in a default on our debt obligations, including the Convertible Notes.

The issuance of shares of Common Stock upon conversion of the Convertible Notes could substantially dilute your investment and could impede our ability to obtain additional financing.

In additionThe Convertible Notes are convertible into shares of our Common Stock and give the holders an opportunity to selling securitiesprofit from a rise in capital raising transactionsthe market price of our Common Stock such that conversion or exercise thereof could result in dilution of the equity interests of our shareholders. We have no control over whether the holders will exercise their right to supportconvert their Convertible Notes. While the Convertible Notes are convertible at a minimum price of $4.10 per share which is higher levelthan our current market price, we cannot predict the market price of growth, respondour Common Stock at any future date, and therefore, cannot predict whether the Convertible Notes will be converted. The existence and potentially dilutive impact of the Convertible Notes may prevent us from obtaining additional financing in the future on acceptable terms, or at all.

DESCRIPTION OF THE TRANSACTION

Private Placement of Convertible Notes

Loan and Security Agreement and Convertible Notes

On December 15, 2020 (the “Closing Date”) we and certain of our subsidiaries entered into the Loan and Security Agreement with Pontifax Medison Finance (Israel) L.P. and Pontifax Medison Finance (Cayman) L.P., as lenders (collectively, referred to competitive pressures, develop new productsas “Lenders”), and servicesPontifax Medison Finance GP, L.P., in its capacity as administrative agent and support new strategic partnership expenditures, we may issue shares in connection with (i)collateral agent for itself and the achievement of clinical development milestonesLenders (the “Agent”). The Lenders under license or purchase agreements, suchthe Loan and Security Agreement are referred to herein as the asset purchase agreement“selling stockholders.”

Amount. The Loan and Security Agreement provides for a term loan or loans in an aggregate principal amount of up to $20.0 million (the “Term Loan”) subject to funding in three tranches as follows: (a) within two (2) business days after the Closing Date, a loan in the aggregate principal amount of $10.0 million (the “Initial Loan”), (b) during the 12 month period after the Closing Date, a credit line in the aggregate principal amount of $5.0 million (the “Credit Line”), and (c) a loan in the aggregate principal amount of $5.0 million (the “Third Installment Loan”) shall be made available for withdrawal in full upon the filing of a new Drug Application with Hy Biopharma Inc. pursuant to which we acquired assets related to the development ofFDA for our synthetic hypericin product candidate for the treatment of cutaneous T-cell lymphoma, (SGX301),SGX301, which shall be deemed to occur on the date of initial filing with the FDA.

Maturity. The Term Loan matures 54 months following the Closing Date (the “Maturity Date”). All amounts outstanding under the Term Loan will be due and (ii) strategic partnering and/payable upon the earlier of the maturity date or acquisition transactions involving the issuanceacceleration of our securities as well asthe loans and commitments upon an event of default.

Interest Rate, Fees. The principal balance of the Term Loan bears interest at 8.47% per annum based on a year consisting of 365 days. Interest is payable on a quarterly basis based on the principal amount outstanding during the preceding quarter. In addition, we are required to meet long-term corporate objectives. 

There is no guarantee that we will sell the securities described in this prospectus and, in the event that we do, there is no guarantee aspay to the total numberselling stockholders an unused line fee of securities that1.0% per annum payable quarterly on the amount not withdrawn under the Credit Line and, upon withdrawal of the Third Installment Loan, we would sell, nor is there any guarantee asare required to pay a fee of 1.0% of the Third Installment Loan to the amountselling stockholders.

Amortization. Commencing on the last business day of net proceedsthe calendar quarter prior to be used specifically for the foregoing purposes. Our management will have significant discretionlapse of 24 months following the Closing Date and flexibilitycontinuing on the first business day of each quarter thereafter until the Maturity Date, the Initial Loan, the Credit Line and the Third Installment Loan shall amortize in applying the net proceeds from the sale of these securities. Our plans to use the estimated net proceeds from the sale of these securities may change and, if they do, we will update this information in a prospectus supplement.ten equal quarterly installments.

Prepayment Premium. Following 18 months from the Closing Date, we may, at our option upon at least 14 business days’ written notice to the Agent, prepay an amount of not less than $500,000 or all of the then outstanding principal balance and all accrued and unpaid interest on the Term Loan, together with a prepayment charge equal to one percent (1.0%) of the principal amount being prepaid.

Conversion by the selling stockholders. The selling stockholders may, at their option and at any time, elect to convert the then outstanding Term Loan amount and all accrued and unpaid interest thereon into shares of Common Stock at a conversion price of $4.10 (the “Conversion Price”), subject to certain customary adjustments as specified in the Loan and Security Agreement.

Conversion by the Company. We have the right to convert, at any time, any outstanding portion of the Term Loan and all accrued and unpaid interest thereon into shares of Common Stock at the Conversion Price, subject to fulfilment of all of the following conditions: (i) the shares of Common Stock issuable upon conversion are unrestricted and freely tradable securities if held by a person that is not an affiliate (and has not been affiliate at any time during the three months preceding any such sale) of ours pursuant to Rule 144 under the Securities Act of or under an effective registration statement under the Securities Act, (ii) during a period of 30 consecutive trading days prior to the date on which we give notice of the exercise of our conversion right, the closing price of the Common Stock was higher than $4.92 on at least 10 trading days, which trading days need not be consecutive, including on the trading day preceding the date on which we give notice of the exercise of its conversion right, and (iii) the number of shares of Common Stock issuable upon conversion by us shall not exceed the average weekly number of traded shares on the stock market during the four weeks immediately preceding the date on which we give notice of the exercise of our conversion right. We may only effect a conversion once every four weeks.

Security. Our obligations under the Term Loan are secured by a security interest, senior to any current and future debts and to any security interest, in all of our right, title, and interest in, to and under all of the following personal property of Borrower whether now owned or hereafter acquired (collectively, the “Collateral”): (a) receivables; (b) equipment; (c) fixtures; (d) general intangibles (other than Intellectual Property); (e) inventory; (f) investments; (g) deposit accounts; (h) cash; (i) goods; (j) licenses; (k) franchise agreements, (l) commercial tort claims; and all other tangible and intangible personal property of Borrower whether now or hereafter owned or existing; and, to the extent not otherwise included, all proceeds of each of the foregoing and all accessions to, substitutions and replacements for, and rents, profits and products of each of the foregoing, subject to limited exceptions including our intellectual property.

Covenants; Representations and Warranties; Other Provisions. The Loan and Security Agreement contains customary representations, warranties and covenants, including covenants by us limiting additional indebtedness, liens, including on intellectual property, guaranties, mergers and consolidations, substantial asset sales, investments and loans, certain corporate changes, transactions with affiliates and fundamental changes.

Default Provisions. The Loan and Security Agreement provides for events of default customary for term loans of this type, including but not limited to non-payment, breaches or defaults in the performance of covenants, insolvency, bankruptcy and the occurrence of a material adverse effect on us. After the occurrence and continuance of an event of default the Agent has the option to (i) accelerate payment of all obligations and terminate the selling stockholders’ commitments under the Loan and Security Agreement, (ii) sign and file in our name any notices, assignment or agreements necessary to perfect repayment, (iii) notify any of our account debtors to make payment directly to Agent and (iv) exercise its security interests in the Collateral.

DESCRIPTIONS OF THE SECURITIES WE MAY OFFER

Registration Rights Agreement

We may sell from time to time, in one or more offerings, shares of our common stock and/or preferred stock, warrants to purchase common stock and/or preferred stock, and units in one or more offerings, and/or units consisting of one or more of the foregoing securities.

The descriptions of the securities contained in this prospectus, togetherIn connection with the additional informationLoan and Security Agreement, we include in any applicable prospectus supplement or in any free writing prospectuses we have authorized for use in connection withentered into a specific offering, summarize some of the terms and other provisions of the various types of securities that we may offer under this prospectus. These summary descriptions are not meant to be complete descriptions of each security. We will describe in the applicable prospectus supplement relating to a particular offering the specific terms of the securities offered under that prospectus supplement. The applicable prospectus supplement for a particular security may specify different or additional terms.

DESCRIPTION OF CAPITAL STOCK

General

The following description of our common stock and preferred stock, togetherRegistration Rights Agreement (the “Registration Rights Agreement”) with the additional informationselling stockholders, pursuant to which we include in any applicable prospectus supplement or in any free writing prospectuses we have authorizedagreed to, among other things, use commercially reasonable efforts to (i) file a registration statement within 60 days following the Closing Date for use in connection with a specific offering, summarizes somethe purpose of the terms and provisions ofregistering for resale the shares of our common stock and preferred stock that we may offer under this prospectus. These summary descriptions of our common stock and preferred stock are not meant to be complete descriptions of each security. For the complete terms of our common stock and preferred stock, please refer to our Certificate of Incorporation, as may be amended from time to time, any certificates of designation for our preferred stock that may be authorized from time to time, and our bylaws, as amended from time to time. The Delaware General Corporation Law may also affect the terms of these securities. While the terms we have summarized below will apply generally to any future common stock or preferred stock that we may offer under this prospectus, we will describe the specific terms of any series of these securities in more detail in the applicable prospectus supplement. The applicable prospectus supplement for a particular offering of our common stock or preferred stock may specify different or additional terms.

AsCommon Stock issuable upon conversion of the date hereof, our authorized capital stock consists of 50,350,000 shares of capital stock, of which 50,000,000 shares are common stock, par value $0.001 per share, 230,000 shares are undesignated preferred stock, 10,000 shares are Series B Convertible Preferred Stock, par value $0.05 per share (none of which are currently outstanding), 10,000 shares are Series C Convertible Preferred Stock, par value $0.05 per share (none of which are currently outstanding)Term Loan (the “Conversion Shares”) and 100,000 shares are Series A Junior Participating Preferred Stock, par value $0.001 per share (none of which are currently outstanding). As of the date of this prospectus, there wereany other securities issued and outstanding 28,956,475 shares of common stock, options to purchase 1,491,480 shares of common stock and warrants to purchase 5,886,817 shares of common stock.

Common Stock

Voting Rights

Holders of our common stock are entitled to one vote for each share held in the election of directors and in all other matters to be voted on by the stockholders. There is no cumulative voting in the election of directors. The affirmative vote of the holders of a plurality of the shares of common stock represented at an annual meeting is required to elect each director.

Dividends and Liquidation Rights

Holders of common stock are entitled to receive dividends as may be declared from time to time by our board of directors out of funds legally available therefor. In the event of liquidation, dissolution or winding up of the corporation, holders of common stock are to share in all assets remaining after the payment of liabilities.

Conversion, Redemption and Other Rights

Holders of common stock have no pre-emptive or conversion rights and are not subject to further calls or assessments. There are no redemption or sinking fund provisions applicable to the common stock. The rights of the holders of the common stock are subject to any rights that may be fixed for holders of preferred stock.

Preferred Stock

Our Certificate of Incorporation authorizes the issuance of 230,000 shares of undesignated preferred stock, 10,000 shares of Series B Convertible Preferred Stock, par value $0.05 per share (“Series B Preferred Stock”), 10,000 shares of Series C Convertible Preferred Stock, par value $0.05 per share (“Series C Preferred Stock”), and 100,000 shares of Series A Junior Participating Preferred Stock, par value $0.001 per share (“Junior Preferred Stock”). Our board of directors is empowered, without stockholder approval, to designate and issue additional series of preferred stock with dividend, liquidation, conversion, voting or other rights, including the right to issue convertible securities with no limitations on conversion, which could adversely affect the voting power or other rights of the holders of our common stock, substantially dilute a common stockholder’s interest and depress the price of our common stock.

No shares of the Series B Preferred Stock, the Series C Preferred Stock or the Junior Preferred Stock are outstanding. Due to the terms of the Series C Preferred Stock, no additional shares of Series C Preferred Stock can be issued.

Series B Preferred Stock

Our Certificate of Incorporation authorizes the issuance of 10,000 shares of Series B Preferred Stock, none of which are outstanding and 6,411 of which have been converted to common stock and therefore are not reissuable.

Voting Rights

Each holder of Series B Preferred Stock is entitled to the number of votes equal to the number of whole shares of common stock into which the shares of Series B Preferred Stock held by such holder is then convertible (as adjusted from time to time pursuant to our Certificate of Incorporation)issuable with respect to or in exchange for such Conversion Shares, whether by merger, charter amendment or otherwise (ii) make the registration statement declared effective as soon as practicable after filing, and in any event no later than 120 days after the Closing Date, and (iii) maintain the registration until all matters presentedregistrable securities may be sold by the selling stockholders pursuant to Rule 144 under the stockholders for their actionSecurities Act, without restriction as to manner, sale or consideration. Except as provided by law, holdersvolume restrictions. If the registration statement is not timely filed or declared effective, we will be required to pay a ticking fee of Series B Preferred Stock vote together with the holders of common stock as a single class.

Dividends and Liquidation Rights

The holders0.5% of the Series B Preferred Stock are entitled to a dividend of 8% per annum, payable annually in shares of Series B Preferred Stock. In addition, when and if our board of directors shall declare a dividend payable with respect to the thenaggregate outstanding shares of common stock, the holdersbalance of the Series B Preferred Stock are entitled toTerm Loan at the amounttime of dividends per share as would be payable on the largest numbersuch failure and each 30 days thereafter until cured. The Registration Rights Agreement contains customary terms and conditions for a transaction of whole shares of common stock into which each share of Series B Preferred Stock could then be converted.this type.

InUse of Proceeds

We will not receive any proceeds from the event of liquidation, dissolution or winding upsale of the company,shares of Common Stock by the holders of Series B Preferred Stock then outstandingselling stockholders.

The selling stockholders will be entitled to be paid an amount equal to $1,000 per share (subject to adjustment in the event of any stock dividend, stock split, combinationpay all underwriting discounts, selling commissions and expenses incurred by them for brokerage, accounting, tax or other similar recapitalization affecting such shares pursuant to our Certificate of Incorporation), plus any dividends declared but unpaid thereon before any payment is made to the holders of common stock, Junior Preferred Stocklegal services or any other class or seriesexpenses incurred by the selling stockholders in connection with the sale of stock ranking on liquidation juniorthe shares, if any. We will bear all other costs, fees and expenses incurred in effecting the registration of the shares covered by this prospectus, including, without limitation, all registration and filing fees, NASDAQ listing fees and fees and expenses of our counsel and our accountants.

SELLING STOCKHOLDERS

The shares of Common Stock being offered for resale by the selling stockholders pursuant to the Series B Preferred Stock. AfterForm S-3 of which this prospectus forms a part are the holdersshares of the Series B PreferredCommon Stock have been paid in full, the remaining assets of the company will be distributedissuable to the holders of Junior Preferred Stock and common stock, subject to the preferences of the Junior Preferred Stock.

Conversion, Redemption and Other Rights

Each share of Series B Preferred Stock is convertible into 1.333 shares of common stock. The conversion ratio is subject to an adjustment upon the issuance of additional shares of common stock for a price below the closing price of the common stock and equitable adjustment for stock splits, dividends, combinations, reorganizations and similar events.

Subject to certain conditions, after the second anniversary of the issuance of the Series B Preferred Stock, the company will have the right, but not the obligation, to redeem the then-outstanding shares of Series B Preferred Stock for cash in an amount calculatedselling stockholders pursuant to the terms of our Certificatethe Convertible Notes. For additional information regarding the issuance of Incorporation.

Junior Preferredthose Convertible Notes, see the section of this prospectus titled “Description of the Transaction.” We are registering the shares of Common Stock

Voting Rights in order to permit the selling stockholders to offer the shares for resale from time to time. Except for the ownership of the Convertible Notes issued pursuant to the Loan and Security Agreement and as described below, the selling stockholders have not had any material relationship with us within the past three years.

The holders oftable below lists the Junior Preferred Stock will have 10,000 votes per share of Junior Preferred Stock on all matters submitted to a vote of ourselling stockholders includingand other information regarding the election of directors.

Dividends and Liquidation Rights

If our board of directors declares or pays dividends on common stock, the holders of the Junior Preferred Stock would be entitled to receive a per share dividend payment of 10,000 times the dividend declared per share of common stock. In the event we make a distribution on the common stock, the holders of the Junior Preferred Stock will be entitled to a per share distribution, in like kind, of 10,000 times such distribution made per share of common stock. In the event of any merger, consolidation or other transaction in which shares of common stock are exchanged, each share of Junior Preferred Stock will be entitled to receive 10,000 times the amount received per share of common stock. These rights are protected by customary anti-dilution provisions.

Upon any liquidation, dissolution or winding up, no distribution may be made to the holdersbeneficial ownership of shares of stock ranking junior to the Junior PreferredCommon Stock unless the holdersby each of the Junior Preferred Stock have received the greater of (i) $37.00 per one one-thousandth share plus an amount equal to accrued and unpaid dividends and distributions thereon, and (ii) an amount equal to 10,000 times the aggregate amount to be distributed per share to holders of common stock. Further, no distribution may be made to the holders of stock ranking on a parity upon liquidation, dissolution or winding up with the Junior Preferred Stock, unless distributions are made ratably on the Junior Preferred Stock and all other shares of such parity stock in proportion to the total amounts to which the holders of the Junior Preferred Stock are entitled above and to which the holders of such parity shares are entitled.

Outstanding Warrants

2016 Warrants

On December 16, 2016, we consummated a public offering of an aggregate of 1,670,000 shares of common stock, together with warrants to purchase up to 2,370,005 shares of common stock. In connection with the offering, we also issued the underwriter a warrant to purchase up to 33,400 shares of common stock. We refer to the warrants issued to the investors and the underwriter in connection with the offering as the “2016 Warrants.”selling stockholders. The 2016 Warrants are listed on The Nasdaq Capital Market under the symbol “SNGXW”.

As of July 13, 2020, 2,403,405 shares of common stock remained issuable upon the exercise of the 2016 Warrants. The 2016 Warrants expire in 2021.

As of July 13, 2020, the exercise price of the 2016 Warrants was $3.95 per share. The exercise price andsecond column lists the number of shares of common stock purchasable upon the exercise ofCommon Stock beneficially owned by each 2016 Warrant are subject to adjustment upon the happening of certain events, such as stock dividends, distributions, and splits.

Other Warrants

As of July 13, 2020, 3,483,412 shares of common stock were issuable upon the exercise of warrants other than the 2016 Warrants. Such warrants expire between 2022 and 2023. As of July 13, 2020, the weighted average exercise price of such warrants was $2.20 per share. The exercise price and the number of shares of common stock purchasable upon the exercise of each such warrant are subject to adjustment upon the happening of certain events, such as stock dividends, distributions, and splits.

Anti-Takeover Provisions

Provisions in our Certificate of Incorporation and Bylaws may discourage certain types of transactions involving an actual or potential change of control of our company which might be beneficial to us or our security holders.

As noted above, our Certificate of Incorporation permits our board of directors to issue shares of any class or series of preferred stock in the future withoutselling stockholder, approval and upon such terms as our board of directors may determine. The rightsbased on its ownership of the holdersConvertible Notes, as of common stock will be subject to, and may be adversely affected by,January 13, 2021, assuming conversion of all Convertible Notes at the rightsconversion price in effect as of the holders of any class or series of preferred stock that may be issued in the future.

Our Bylaws generally provide that any board vacancy, including a vacancy resulting from an increase in the authorized number of directors, may be filled by a majority of the directors, even if less than a quorum.

Additionally, our Bylaws provide that stockholders must provide timely notice in writing to bring business before an annual meeting of shareholders or to nominate candidates for election as directors at an annual meeting of shareholders. Notice for an annual meeting is timely if our Secretary receives the written notice not less than 45 days and no more than 75 days prior to the anniversary of the date that we mailed proxy materials for thetrading day immediately preceding year’s annual meeting. However, if the date of the annual meeting is advanced more than thirty (30) days prior to, or delayed by more than thirty (30) days after, the anniversary of the preceding year’s annual meeting, notice by the stockholder to be timely must be delivered not later than the close of business on the later of (i) the 90^th day prior to such annual meeting or (ii) the 10^th day following the day on which public announcement of the date of such annual meeting is first made. Our Bylaws also specify the form and content of a shareholder’s notice. These provisions may prevent shareholders from bringing matters before an annual meeting of shareholders or from making nominations for directors at an annual meeting of shareholders.

Delaware Anti-Takeover Statute

We are subject to the provisions of Section 203 of the Delaware General Corporation Law regulating corporate takeovers. In general, Section 203 prohibits a publicly held Delaware corporation from engaging, under certain circumstances, in a business combination with an interested stockholder for a period of three years following the date the person became an interestedregistration statement is initially filed with the SEC. The third column lists the shares of Common Stock being offered by this prospectus by the selling stockholders. The fourth column lists the shares of Common Stock held by each selling stockholder unless:after completion of this offering, and assumes that each selling stockholder subsequently sells all of the shares covered by this prospectus and assumes full conversion of the Convertible Notes. The fifth column lists the percentage ownership held by each selling stockholder after completion of this offering. The information presented regarding the selling stockholders is based, in part, on information the selling stockholders provided to us in writing specifically for use in this prospectus. The selling stockholders may sell all, some or none of their shares in this offering. See the section of this prospectus titled “Plan of Distribution.”

In addition to the assumptions described above, beneficial ownership is determined in accordance with the rules of the SEC and generally includes voting or investment power over securities. To our knowledge, unless otherwise indicated, all persons named in the table below have sole voting and investment power with respect to their shares of Common Stock. Percentage of beneficial ownership is based on 31,485,362 shares of our Common Stock outstanding as of January 13, 2021.