As filed with the Securities and Exchange Commission on May 30, 2017February 6, 2018

Registration No. 333 - 218062

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Amendment No. 1

to

Form S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

Diffusion Pharmaceuticals Inc.

(Exact name of registrant as specified in its charter)

David G. Kalergis
Chief Executive Officer
2020 Avon Court, #41317 Carlton Avenue, Suite 200
Charlottesville, VA 22902
(434) 220-0718

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

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,plans, check the following box. ☐☒

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 for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

CALCULATION OF REGISTRATION FEE

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

SUBJECT TO COMPLETION, DATED MAY 30, 2017

FEBRUARY 6, 2018

Diffusion Pharmaceuticals Inc.

 
Common Stock
Up to 26,467,80112,262,447 Shares of Common Stock
Offered by the Selling Stockholders

This prospectus relates to the resale or other disposition from time to time by the selling stockholders identified herein (including, except as the context may otherwise require, their donees, pledgees, transferees or other successors-in-interest, the “Selling Stockholders”), of, subject to adjustment, up to26,467,801 12,262,447 shares of the common stock, $0.001 par value per share (the “Common Stock”), of Diffusion Pharmaceuticals Inc. (the “Company”). Of these shares, (a) 12,376,329594,026 are issued and outstandingshares (the “Dividend Shares”) issuable as a resultpayment of or issuable upon,dividends accruing from October 1, 2017 through January 22, 2018 with respect to the conversion of the Company’s previously outstanding shares of Series A convertible preferred stock, $0.001 par value per share (the “Series A Preferred Stock”), and (b) 13,555,88711,668,421 are issuedshares (the “Make-Whole Shares”) issuable pursuant to Section 4(g) of the the Certificate of Designation of Preferences, Rights and outstandingLimitations of the Series A Convertible Preferred Stock of Diffusion Pharmaceuticals Inc. (the “Certificate of Designation”), in each case, as a result of or issuable upon, the exercise of warrants to purchase shares of Common Stock (the “Warrants”) and (c) an estimated 535,585 are issuable as payment of dividends accruing through October 1, 2017 with respect to the Series A Preferred Stock.Mandatory Conversion (as defined herein). The Selling Stockholders acquired rights to receive all of the securities covered by this prospectus in connection with a private placement transaction in which we sold the Series A Preferred Stock and accompanying warrants to purchase Common Stock (the “Warrants”) to accredited investors in closings conducted on March 14, 2017 and March 31, 2017 (or, as applicable, a subsequent donation, pledge or transfer thereof). We are registering the resale or other disposition of the shares of Common Stock to satisfy registration rights we have granted to the Selling Stockholders.

Our registration of the shares of Common Stock covered by this prospectus does not mean that the Selling Stockholders will offer or sell any of the shares. The Selling Stockholders(includingStockholders (including their donees, pledgees, transferees or other successors-in-interest) may, from time to time, resell or otherwise dispose of any or all of the shares of Common Stock described in this prospectus on any stock exchange, market or trading facility on which the shares are traded or in private transactions. These sales may be at fixed or negotiated prices, and may be to or through underwriters, broker-dealers or agents, who may receive compensation in the form of discounts, concessions or commissions. The Selling Stockholders will pay all underwriting discounts, commissions and any similar expenses it incurs, if any, in connection with the sale of the shares of Common Stock, and any related legal expenses incurred by it. We have agreed to pay certain expenses in connection with this registration statement and to indemnify the Selling Stockholders against certain liabilities. None of our shares of Common Stock may be sold without delivery of the applicable prospectus supplement describing the method and terms of the offering of the Common Stock. See “Plan of Distribution” beginning on page 19 22 for more information regarding the manners in which Selling Stockholders may sell or dispose of the securities registered hereby.

We are not selling any shares of Common Stock under this prospectus and will not receive any of the proceeds from the sale of shares of Common Stock by the Selling Stockholders. To the extent Warrants are exercised for cash, if at all, we will receive the exercise price thereof.

You should read this prospectus, any applicable prospectus supplement and any related free writing prospectus carefully before you invest.

Our Common Stock is traded on the NASDAQ Capital Market under the symbol “DFFN.” On May 26, 2017,February 5, 2018, the last reported sale price of our Common Stock was $2.72$0.61 per share.

Investing in our Common Stock involves significant risks.risks. See “Risk Factors” on page7 of this prospectus, in our most recent Annual Report on Form 10-K,, any of our other filings with the Securities and Exchange Commission and in any applicable prospectus supplement. You should read this prospectus, any accompanying prospectus supplement, and the documents incorporated by reference herein and therein carefully before you make your investment decision.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the Common Stock being offered hereby or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

This prospectusprospectus is dated _________, 2017February 6, 2018

TABLE OF CONTENTS

Page

ABOUT THIS PROSPECTUS 

This prospectus is part of a registration statement on Form S-3 that we filed with the U.S. Securities and Exchange Commission, or the Commission, using a “shelf” registration process. Under this process, the Selling Stockholders may from time to time, in one or more offerings, sell the Common Stock described in this prospectus.

You should rely only on the information provided in this prospectus, the related prospectus supplement, including any information incorporated by reference, and any pricing supplement. No one is authorized to provide you with information different from that which is contained, or deemed to be contained, in the prospectus, the related prospectus supplement and any pricing supplement. The Selling Stockholders are not making offers to sell Common Stock in any jurisdiction in which an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should not assume that the information in this prospectus, any prospectus supplement or any document incorporated by reference is accurate as of any date other than the date of the document in which the information is contained or other date referred to in that document, regardless of the time of sale or issuance of the Common Stock.

This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the Common Stock, you should refer to the registration statement including the exhibits. This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information.” We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference in this prospectus were made solely for the benefit of the parties to such agreement, including in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

Unless otherwise specified or unless the context requires otherwise, all references in this prospectus to “Diffusion,” the “Company,” “we,” “us,” “our” or similar references mean Diffusion Pharmaceuticals Inc. and its subsidiaries on a consolidated basis.

We have registered trademarks for RestorGenexDiffusion and Diffusion.RestorGenex. All other trade names, trademarks and service marks appearing in this prospectus are the property of their respective owners. Use or display by us of other parties’ trademarks, trade dress or products is not intended to and does not imply a relationship with, or endorsements or sponsorship of, us by the trademark or trade dress owner.

PROSPECTUS SUMMARY

The following is a summary of what we believe to be the most important aspects of our business and the offering of our common stock under this prospectus. This summary does not contain all of the information that should be considered before investing in our common stock. Investors should read the entire prospectus carefully, including the risks related to our business and purchasing our common stock discussed under “Risk Factors” beginning on page 7 of this prospectus, “Special Notes Regarding Forward Looking Statements” and our financial statements and the notes to those financial statements incorporated by reference in this prospectus.

Diffusion Pharmaceuticals Inc.

Business Overview

We are a clinical stage biotechnology company focused on extending the life expectancy of cancer patients by improving the effectiveness of current standard-of-care treatments, including radiation therapy and chemotherapy. We are developing our lead product candidate,transcrocetinate sodium,, also known astrans sodium crocetinate (“TSC”), for use in the many cancer types in which tumor oxygen deprivation (“hypoxia”) is known to diminish the effectiveness of current treatments. TSC is designed to target the cancer’s hypoxic micro-environment, re-oxygenatingre-oxygenate treatment-resistant tissue and makingmake the cancer cells more susceptible to the therapeutic effects of standard-of-care radiation therapy and chemotherapy.

Our lead development programs target TSC against cancers known to be inherently treatment-resistant, includingwith a focus on brain cancers and pancreatic cancer.cancers. A Phase 1/2 clinical program, completed in the secondfourth quarter of 2015, evaluated 59 patients with newly diagnosed glioblastoma multiforme (“GBM”)., a particularly deadly form of primary brain cancer. This open label, historically controlled study demonstrated a favorable safety and efficacy profile for TSC combined with standard of care, including a 37%36% improvement in overall survival over the control group at two years. A particularly strong efficacy signal was seen in the inoperable patients, where survival of TSC-treated patients at two years was increased by 380%almost four-fold over the controls. At an End-Of-Phase 2 Meeting, theThe U.S. Food and Drug Administration, or FDA, has provided Diffusion with extensivefinal protocol guidance on the design for a Phase 3 trial of TSC in this newly diagnosed inoperable GBM patients. We believe focusing on the inoperable patient group in Phase 3 should reduce the needed number of patients from over 400population. The Company has responded to around 230, which is expected to provide real cost savings, while the strength of the Phase 2 efficacy signal should make the showing of significant clinical gain in Phase 3 more likely. Assuming FDA sign-off on our final protocol design, focusing on the inoperable patients, the study is planned to initiateall outstanding points raised by the end of 2017.FDA and recently announced the trial has opened for enrollment and dosed its first patient under the protocol permitted by the FDA. The trial will enroll 236 patients in total, 118 in each arm. Due to its novel mechanism of action, TSC has safely re-oxygenated a range of tumor types in our preclinical and clinical studies. Diffusion believes its therapeutic potential is not limited to one specific tumors,tumor type, thereby making it potentially useful to improve standard-of-care treatments of other life-threatening cancers. Additional planned studies include aGiven TSC's safety profile and animal data, we can, with appropriate funding, move directly into Phase 2 trialstudies in pancreatic cancer and a study in brain metastases, with a study initiation subject to receipt of additional funding or collaborative partnering.other cancers. We also believe that TSC has potential application in other indications involving hypoxia, such as neurodegenerative diseases and emergency medicine. For example, oura stroke program is now in advanced discussionsunder discussion with doctors from UCLA and the University of Virginia, with whom we have established a joint team dedicated to developing a program to test TSC in the treatment of stroke, with an in-ambulance trial of TSC in stroke under consideration. Planning for such a trial is on-going.

In addition to the TSC programs, we are exploring alternatives regarding how best to capitalize upon the legacy RestorGenexour product candidate RES-529, which may include possible out-licensing and other options. RES-529 is a novel PI3K/Akt/mTOR pathway inhibitor which has completed two Phase I1 clinical trials for age-related macular degenerationdegeneration and was in preclinical developmenthas been studied preclinically in oncology, specifically GBM. RES-529 has shown activity in both in vitro and in vivo glioblastoma animal models and has been demonstrated to be orally bioavailable and can cross the blood brainblood-brain barrier.

Corporate Information

Corporate Information

We are a Delaware corporation. We maintain our principal executive offices at 2020 Avon Court,1317 Carlton Avenue, Suite #4,200, Charlottesville, VA 22902. Our telephone number there is (434) 220-0718. The address of our website iswww.diffusionpharma.com. The information set forth on, or connected to, our website is expressly not incorporated by reference into, and does not constitute a part of, this prospectus.

Summary of Private PlacementSeries A Preferred Stock, January Offering and Mandatory Conversion

Series A Preferred Stock

In March 2017, we conducted a private placement (the “Private Placement”), pursuant to which we issued 12,376,329 shares of the Series A Preferred Stock, initiallyeach convertible into one share of Common Stock, and 5-year warrants to purchase 12,376,329 shares of Common Stock at an exercise price equal to $2.22 per share (the “Investor Warrants”). The aggregate gross proceeds from the Private Placement were $25.0 million, prior to deducting placement agent fees and expenses payable by us. Maxim Merchant Capital, a division of Maxim Group LLC (“Maxim”), acted as our sole placement agent in the Private Placement. We issued to Maxim and its designees (who are included as Selling Stockholders) 5-year warrants, to purchase of 1,179,558 shares of Common Stock at an exercise price equal to $2.22 per share, with such warrants containing a cashless exercise provision (the “Maxim Warrants” and, together with the Investor Warrants, the “Warrants”). The securities were issued to accredited investors in reliance upon an exemption pursuant to Section 4(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”), and the rules and regulations promulgated thereunder. Please see “Description of Capital Stock” for a description of our Common Stock, Series A Preferred Stock and Warrants.

As partPursuant to the Certificate of Designation, among other things, (i) the Private Placement, we entered into registration rights agreements with the investors in the Private Placement and Maxim (the “Registration Rights Agreement”), pursuant to which we agreed to file a registration statement to register for resale the shares of common stock (i) issued and outstanding as a result of, or issuable upon, the conversion of the sharesholders of Series A Preferred Stock (ii) issued and outstanding as a result of, or issuable upon, the exercise of the Warrants sold in the Private Placement and (iii) issuable as payment of dividends accruing on the Series A Preferred Stock. We are required to use our commercially reasonable best efforts to cause the registration statement to be declared effective under the Securities Act, as soon as practicable, but in no event later than 120 days after the final closing of the Private Placement, which occurred on March 31, 2017 (the “Final Closing”). We agreed to keep the registration statement effective until the earlier of (i) 66 months after the Final Closing or (ii) all registrable securities may be sold pursuant to Rule 144 under the Securities Act or another similar exemption under the Securities Act. We also agreed, among other things, to indemnify the investors under the registration statement from certain liabilities and to pay all fees and expenses incident to our performance of or compliance with the Registration Rights Agreement.

Series A Convertible Preferred Stock

Voting. The holders of the Series A Preferred Stock will be entitled to vote with the holders of Common Stock (and any other class or series that may similarly be entitled to vote with the holders of Common Stock as the Board may authorize and issue) and not as a separate class, at any annual or special meeting of stockholders of the Company, and may act by written consent in the same manner as the holders of Common Stock. In the event of any such vote or action by written consent, each holder of shares of Series A Preferred Stock shall be entitled to that number of votes equal to the whole number of shares of Common Stock into which the aggregate number of shares of Series A Preferred Stock held of record by such holder are convertible as of the close of business on the record date fixed for such vote or such written consent based on a conversion price, solely for such purpose, equal to the closing price of our Common Stock on the date such Series A Preferred Stock was issued. In addition, for as long as 50% of the shares of Series A Preferred Stock outstanding immediately after the final closing remain outstanding, without the consent of holders of at least a majority of the then outstanding shares of Series A Preferred Stock, we may not (a) amend our amended and restated certificate of incorporation (the “Certificate of Incorporation”) and amended and restated bylaws (the “Bylaws”)so as to materially and adversely affect any rights of the holders of the Series A Preferred Stock, (b) increase or decrease (other than by conversion of the Series A Preferred Stock) the authorized number of Series A Preferred Stock to be in excess of the number of shares required to satisfy the maximum offering amount of the Private Placement, (c) amend the Certificate of Designation of Preferences, Rights and Limitations of the Series A Convertible Preferred Stock of Diffusion Pharmaceuticals Inc. (the “Certificate of Designation”), (d) repay, repurchase or offer to repay, repurchase or otherwise acquire more than ade minimis number of shares of Common Stock or Common Stock equivalents or (e) enter into any agreement or understanding with respect to (a) through (d).

Dividends. The Series A Preferred Stock will bewere entitled to an 8.0% cumulative preferred dividend payable semi-annually on each April 1 and October 1 in cash or shares of Common Stock that will begin accruing on(at the issue datediscretion of the Series A Preferred Stock. The dividend will begin to accrue and be cumulative on the first dayour Board of Directors), (ii) each applicable dividend period and shall remain accumulated dividends with respect to such Series A Preferred Stock until paid; provided, that the first dividend payable with respect to any share of Series A Preferred Stock shall not begin to accrue until the date of original issuance of such share of Series A Preferred Stock. Dividends shall accrue whether or not there are profits, surplus or other funds of the Company legally available for the payment of dividends but shall not be payable until legally permissible, as applicable.

Liquidation. The Series A Preferred Stock will rank senior to the Common Stock and each other class of capital stock of the Company or series of Series A Preferred Stock of the Company authorized by the Board in the future that does not expressly provide that such class or series ranks senior to, or on parity with, the Series A Preferred Stock (“Junior Securities”). In the event of a Liquidation Event (as defined in the Certificate of Designation), the holders of the Series A Preferred Stock shall be entitled to receive, out of the assets of the Company or proceeds thereof legally available therefor, an amount in cash equal to 100% of the stated value of the Series A Preferred Stock before any payment or distribution of the assets of the Company is made or set apart for the holders of Junior Securities. In addition, prior to such Liquidation Event, the holders of Series A Preferred Stock shall be entitled to notice so that they may exercise their conversion rights prior to such event. If, upon the occurrence of any Liquidation Event, the assets of the Company, or proceeds thereof, distributable after payment in full of our creditors and any securities senior to the Series A Preferred Stock shall be insufficient to pay in full the aggregate amount of 100% of the stated value to the holders of the Series A Preferred Stock, the assets of the Company, or the proceeds thereof, shall be distributed ratably among the holders of any Series A Preferred Stock and the holders of any security ranked equally with the Series A Preferred Stock.

Conversion Rate: Each share of Series A Preferred Stock iswas convertible into aone share of Common Stock at a conversion price equal to the $2.02, subject to adjustment as provided in the Certificate of Designation and summarized herein (the “Conversion Price”),(x) at any time after the final closing date at the holder’s sole and absolute discretion. Holders may immediately convert their Series A Preferred Stock prior to the occurrence of certain Liquidation Events. Each share of Series A Preferred Stock will automatically convert, initially, into a share of Common Stock (a) on any date that is more than thirty (30) trading days after the original issued date of such share Series A Preferred Stock that the 30 day moving averagediscretion of the closing priceholder and (y) mandatorily upon, among other things, the Company’s receipt of the Common Stock on the NASDAQ Capital Market (or any other exchange where the Common Stock is traded) exceeds $8.00 per share (subject to adjustment in the event of a stock dividend or split), (b) upon a financingaggregate gross proceeds of at least $10 million or (c) upon the majority vote of the voting power of the then outstanding shares of Series A Preferred Stock. We are not required to issuein any fractional shares of Series A Preferred Stock or Common Stockfinancing (a “Financing Mandatory Conversion Trigger”) and (iii) in connection with the conversion of Series A Preferred Stock and may, in each case, at our discretion, pay the holder such amount in cash or deliver an additional whole share in lieu thereof.

Limitations of Conversion: The number of shares of Common Stock issuable upon a conversion of the Series A Preferred Stock that may be acquired by a holder shall be limited to the extent necessary to ensure that, following such conversion (or other issuance), the total number of shares of Common Stock then beneficially owned by such holder and its affiliates and any other persons whose beneficial ownership of Common Stock would be aggregated with the Holder's for purposes of Section 13(d) of the Exchange Act, does not exceed 4.99% of the total number of issued and outstanding shares of Common Stock (including for such purpose the shares of Common Stock issuable upon such conversion). However, any holder may increase or decrease such percentage to any other percentage not in excess of 9.99% of the total number of shares of Common Stock then issued and outstanding provided that such increase in percentage shall not be effective until sixty-one (61) days after notice to the Company.

Dilution Protection. In the event we, at any time after the first date of issue of the Series A Preferred Stock and while at least one share of Series A Preferred Stock is outstanding: (a) pay a dividend or otherwise make a distribution or distributions on shares of its Common Stock or any other equity or equity equivalent securities payable in shares of Common Stock (which, for avoidance of doubt, shall not include any shares of Common Stock issued by the Company upon conversion of the Series A Preferred Stock or any debt securities), (b) subdivide outstanding shares of Common Stock into a larger number of shares, (c) combine (including by way of reverse stock split) outstanding shares of Common Stock into a smaller number of shares or (d) issue by reclassification of shares of Common Stock any shares of capital stock of the Company, then in each case the conversion price shall be multiplied by a fraction of which (x) the numerator shall be the number of shares of Common Stock (excluding treasury shares, if any) outstanding immediately before such event and (y) the denominator shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment made pursuant to this section shall become effective immediately after the effective date of the applicable event described in subsections (a) through (d) above.

Make-Whole Adjustment. In the event we, during the three years immediately following the Initial Closing,March 14, 2017 and subject to certain exceptions, issueissued in anany offering at least $10 million of Common Stock or securities convertible into or exercisable for Common Stock at a per share price less than $2.02, (the “Make-Whole Price”), we willwould be required to issue to the holders of Series A Preferred Stock a number of shares of Common Stock equal to the additional number of shares of Common Stock that such shares of Series A Preferred Stock would be convertible into if the conversion price of the Series A Preferred Stock under the Certificate of Designation was equal to 105% of the Make-Whole Price (the “Make-Whole Adjustment”). WeFor a full description of the preferences, rights and limitations of the Series A Preferred Stock, see the Certificate of Designation, which is filed as Exhibit 3.3 hereto and incorporated herein by reference.

January Offering and Mandatory Conversion

As previously announced, on January 22, 2018, we closed an underwritten public offering (the “January Offering”) of 15,000,000 shares of Common Stock and warrants to purchase 15,000,000 shares of Common Stock. The shares of Common Stock and warrants were sold at a combined public offering price of $0.80 per share and warrant for total gross proceeds of approximately $12 million. Accordingly, because we received more than $10 million in aggregate gross proceeds from the January Offering, the January Offering constituted a Financing Mandatory Conversion Trigger and, substantially concurrently with the completion of the January Offering, all outstanding shares of Series A Preferred Stock mandatorily converted into an equivalent number of shares of Common Stock. Further, in accordance with the Certificate of Designation, we are only obligated to issue shares with respect to athe holders of Series A Preferred Stock as of the date of the Financing Mandatory Conversion Trigger an aggregate of 11,668,421 Make-Whole Shares pursuant to the Make-Whole Adjustment and an aggregate of 593,933 Dividend Shares in respect of accrued but unpaid dividends accruing from October 1, 2017 (the last regular dividend payment date under the first such subsequent offering, if any, followingCertificate of Designation) and the Private Placement.

Warrants Issueddate of the Financing Mandatory Conversion Trigger. The Dividend Shares also include 93 shares of Common Stock issuable in respect of accrued but unpaid dividends on shares of Series A Preferred Stock converted into Common stock voluntarily by the Private Placementholder prior to the closing of the January Offering.

As of May 5, 2017 there were 13,555,887 Warrants issued and outstanding. The Warrants have an exercise price $2.22 per share, are immediately exercisable and are subject to customary anti-dilution adjustments. The Warrants are exercisable until March 31, 2022. The Warrants are subject to a provision prohibiting the exercise of such Warrants to the extent that, after giving effect to such exercise, the holder of such Warrant (together with the holder’s affiliates, and any other persons acting as a group together with the holder or anyresult of the holder’s affiliates), would beneficially own in excess of 19.99%January Offering and the resulting mandatory conversion of the Series A Preferred Stock, no shares of Series A Preferred Stock remain outstanding Common Stock. In addition,as of the Maxim Warrants contain a cashless exercise provision.date of this registration statement.

THE OFFERING

RISK FACTORS

Investing in our Common Stock involves a high degree of risk. Prior to making any decision to invest in our securities, you should carefully consider the information contained or incorporated by reference in this prospectus or in any accompanying prospectus supplement, including, without limitation, the risks described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016 and our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2017, June 30, 2017 and September 30, 2017, which isare incorporated herein by reference, the risk factors described under the caption “Risk Factors” in any applicable prospectus supplement and any risk factors set forth in our other filings with the Commission, pursuant to Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act, before making an investment decision. The occurrence of any of these risks might cause you to lose all or a part of your investment in the offered securities. See “Where You Can Find More Information.”

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any applicable prospectus supplement and the documents incorporated by reference herein contain forward-looking statements within the meaning of Section 21E of the Exchange Act and Section 27A of the Securities Act, and are subject to the safe harbor created by those sections. We have identified some of these forward-looking statements with words like “believe,” “may,” “could,” “would,” “might,” “possible,” “potential,” “will,” “should,” “expect,” “intend,” “plan,” “predict,” “anticipate,” “estimate” and “continue”, the negative of these words, other words and terms of similar meaning and the use of future dates. Forward-looking statements involve risks and uncertainties. These uncertainties include factors that affect all businesses as well as matters specific to us. Forward-looking statements by their nature address matters that are, to different degrees, uncertain. Uncertainties and risks may cause our actual results to be materially different than those expressed in or implied by our forward-looking statements. For us, particular uncertainties and risks include, among others, our history of operating losses and negative cash flow, uncertainties regarding clinical testing, the difficulty of developing pharmaceutical products, obtaining regulatory and other approvals and achieving market acceptance and other risks and uncertainties described in our filings with the Commission, including:

All forward-looking statements in this prospectus, any applicable prospectus supplement and the documents incorporated by reference herein speak only as of the date of this prospectus or any applicable prospectus supplement and are based on our current beliefs and expectations. We undertake no obligation to update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as otherwise required by law.

USE OF PROCEEDS

We will receive no proceeds from the sale of the Common Stock by the Selling Stockholders. To the extent Warrants are exercised for cash, we will receive the exercise price thereof.

The Selling Stockholders will pay any underwriting discounts and commissions and any similar expenses they incur in disposing of the Common Stock, if any, and any related legal expenses incurred by them. We will bear all other costs, fees and expenses incurred in effecting the registration of the Common Stock covered by this prospectus, including all registration and filing fees, fees and expenses of compliance with securities or “blue sky” laws, listing application fees, printing expenses, transfer agent’sagent’s and registrar’s fees, costs of distributing prospectuses in preliminary and final form as well as any supplements thereto, and fees and disbursements of counsel for the Company and all independent certified public accountants and other persons retained by the Company.

THE SELLING STOCKHOLDERS

This prospectus relates to the resale or other disposition from time to time by the Selling Stockholders identified herein (including their donees, pledgees, transferees or other successors-in-interest) of, subject to adjustment, up to26,467,801shares of Common Stock. Of these shares, (a) 12,376,329 are issuedto 11,668,421 Make-Whole Shares and outstanding as a result of, or issuable upon, the conversion of the Series A Preferred Stock, (b) 13,555,887 are issued and outstanding as a result of, or issuable upon, the exercise of the Warrants (including the Maxim Warrants) and (c) an estimated 535,585 are issuable as payment of dividends accruing through October 1, 2017 with respect to the Series A Preferred Stock. We entered into subscription agreements on March 14, 2017 and March 31, 2017 for the sale of an aggregate of 12,376,329 shares of the Series A Preferred Stock for aggregate gross proceeds of approximately $25.0 million in the Private Placement to the investors therein. In addition, each such investor received a Warrant to purchase one share of Common Stock for each share of Series A Preferred Stock purchased by such investor in the Private Placement.594,026 Dividend Shares. In connection with the Private Placement, we entered into the Registration Rights Agreement with such investors.the investors therein. The filing of the registration statement of which this prospectus is a part is pursuant to our obligations to register the shares of Common Stock on behalf of the Selling Stockholders under the Registration Rights Agreement. All expenses incurred with the registration of the Common Stock owned by the Selling Stockholders will be borne by us. This prospectus will not cover subsequent sales of Common Stock purchased from a Selling Stockholder named in this prospectus.

We cannot predict when or whether any of the Selling Stockholders will convert their Series A Preferred Stock or exercise their Warrants and even if they do, we do not know how long the Selling Stockholders will hold the shares of Common Stock acquired upon conversion or exercise, as applicable, before selling them, and we currently have no agreements, arrangements or understandings with the Selling Stockholders regarding the sale or other disposition of any of the shares. The shares of Common Stock covered hereby may be offered from time to time by the Selling Stockholders.

Furthermore, we do not know when or in what amounts the Selling Stockholders may sell or otherwise dispose of the shares covered hereby. The Selling Stockholders might not sell any or all of the shares covered by this prospectus or may sell or dispose of some or all of the shares other than pursuant to this prospectus. Because the Selling Stockholders may not sell or otherwise dispose of some or all of the shares covered by this prospectus and because there are currently no agreements, arrangements or understandings with respect to the sale or other disposition of any of the shares, we cannot estimate the number of the shares that will be held by the Selling Stockholders after completion of the offering. For purposes of the table below, we have assumed that the Selling Stockholders will have sold all of the shares covered by this prospectus upon completion of the applicable offering.

The table below presents information regarding the Selling Stockholders and the shares of our Common Stock that they may sell or otherwise dispose of from time to time under this prospectus. The percentage of beneficial ownership is based upon 10,345,63714,503,976 shares of Common Stock issued and outstanding as of May 5,September 30, 2017. Beneficial ownership is determined under Section 13(d) of the Exchange Act and generally includes voting or investment power with respect to securities and includes any securities that grant the Selling Stockholders the right to acquire Common Stock within 60 days of May 5,September 30, 2017. Information in the table below is based on information provided by or on behalf of the Selling Stockholders. Since the date on which they provided us with the information below, the Selling Stockholders may have sold, transferred or otherwise disposed of some or all of the shares in transactions exempt from the registration requirements of the Securities Act.