Rexahn Pharmaceuticals, Inc. (“Rexahn”) and Ocuphire Pharma, Inc. (“Ocuphire”) have entered into an Agreement and Plan of Merger and Reorganization, dated June 17, 2020, as amended by the First Amendment to Agreement and Plan of Merger and Reorganization dated June 29, 2020 (as amended, the “Merger Agreement”), pursuant to which a wholly owned subsidiary of Rexahn will merge with and into Ocuphire, with Ocuphire surviving as a wholly owned subsidiary of Rexahn (the “merger”).

At the effective time of the merger (the “Effective Time”), each share of common stock of Ocuphire, $0.0001 par value per share (“Ocuphire common stock”), will be converted into the right to receive approximately 4.9398 shares of Rexahn common stock, $0.0001 par value per share (“Rexahn common stock”), assuming Rexahn delivers the minimum amount of net cash required to consummate the merger, subject to adjustment for the reverse stock split of Rexahn common stock to be implemented prior to the consummation of the merger as discussed in this proxy statement/prospectus/information statement, and further adjusted based primarily on Rexahn’s actual net cash on the anticipated closing date of the merger agreed upon by Rexahn and Ocuphire at least five business days prior to the Rexahn special meeting (the “Anticipated Closing Date”) (the “Exchange Ratio”). This Exchange Ratio is an estimate only as of the date hereof and the final Exchange Ratio will be determined pursuant to a formula described in more detail in the Merger Agreement and in the section entitled “The Merger–Merger Consideration and Exchange Ratio” on page 150 of this proxy statement/prospectus/information statement. Prior to the Effective Time, all of Ocuphire’s outstanding convertible notes will convert into Ocuphire common stock and will participate in the merger on the same basis as the other shares of Ocuphire common stock.

In addition, in connection with the transactions contemplated by the merger, on June 17, 2020, Ocuphire and Rexahn entered into a securities purchase agreement, which was amended and restated on June 29, 2020 (as amended from time to time, the “Securities Purchase Agreement”), with certain institutional healthcare investors, accredited investors and directors and officers of Ocuphire (the “Investors”) pursuant to which, among other things, Ocuphire agreed to issue to the Investors shares of Ocuphire common stock immediately prior to the merger and Rexahn agreed to issue to the Investors warrants to purchase shares of Rexahn common stock (the “Investor Warrants”) ten trading days after closing of the merger in a private placement transaction for an aggregate purchase price of $21.15 million (the “Pre-Merger Financing”). Based on the shares and Investor Warrants issued in the Pre-Merger Financing, Rexahn stockholders prior to the merger may own significantly less of the securities of the combined company following closing of the Pre-Merger Financing. For example, assuming an Exchange Ratio of 4.9398 and Rexahn net cash amount of $0, depending on the trading prices of Rexahn common stock on Nasdaq following the closing of the Pre-Merger Financing, the ownership percentage of pre-merger holders of Rexahn common stock could be between 2.0% and 11.2% of the fully-diluted combined company equity securities. For more information regarding the Pre-Merger Financing and potential dilution in connection therewith, see the section entitled “Agreements Related to the Merger—Pre-Merger Financing” on page 186 of this proxy statement/prospectus/information statement.

More information about Rexahn, Ocuphire and the proposed transactions is contained in this proxy statement/prospectus/information statement. Rexahn and Ocuphire urge you to read this proxy statement/prospectus/information statement carefully and in its entirety. IN PARTICULAR, YOU SHOULD CAREFULLY CONSIDER THE MATTERS DISCUSSED UNDER “RISK FACTORS” BEGINNING ON PAGE 35.

Rexahn and Ocuphire are excited about the opportunities the merger brings to both Rexahn’s and Ocuphire’s stockholders, and thank you for your consideration and continued support.

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 proxy statement/prospectus/information statement. Any representation to the contrary is a criminal offense.

The accompanying proxy statement/prospectus/information statement is dated     , 2020, and is first being mailed to Rexahn’s and Ocuphire’s stockholders on or about     , 2020.

Rexahn will assume outstanding and unexercised options to purchase shares of Ocuphire common stock, which in connection with the merger will be converted into options to purchase shares of Rexahn common stock. At the Effective Time, holders of Rexahn common stock (“Rexahn Stockholders”) will continue to own and hold their existing shares of Rexahn common stock subject to the reverse stock split of Rexahn common stock to be implemented prior to the consummation of the merger, and all outstanding and unexercised warrants to purchase shares of Rexahn common stock immediately prior to the Effective Time will remain in effect pursuant to their terms, except that the holders of certain warrants will have the right to exchange their warrants for cash in an amount equal to the Black-Scholes value of such warrants calculated as set forth therein and in accordance with the terms of such warrant. Each existing unexpired, unexercised and unvested option to purchase Rexahn common stock (a “Rexahn Option”) granted pursuant to the Rexahn Pharmaceuticals, Inc. 2013 Stock Option Plan, as amended and restated (the “Rexahn 2013 Plan”), will be accelerated in full pursuant to the Merger Agreement effective as of immediately prior to the Effective Time. Any outstanding and unexercised Rexahn Options granted pursuant to the Rexahn 2013 Plan having an exercise price per share less than the volume-weighted average closing trading price of a share of Rexahn common stock on the Nasdaq Capital Market for the five consecutive trading days ending five trading days immediately prior to the Effective Time (the “Rexahn Closing Price”) will be entitled to receive, subject to required tax withholding (if any), a number of shares of Rexahn common stock calculated by dividing (a) the product of (i) the total number of shares of Rexahn common stock previously subject to such Rexahn Option, and (ii) the excess of the Rexahn Closing Price over the exercise price per share of the Rexahn common stock previously subject to such Rexahn Option by (b) the Rexahn Closing Price. Rexahn Options granted pursuant to the Rexahn 2013 Plan having an exercise price per share equal to or greater than the Rexahn Closing Price will be terminated and cease to exist as of immediately prior to the Effective Time for no consideration. Each existing Rexahn Option granted pursuant to the Rexahn Pharmaceuticals, Inc. Stock Option Plan, as amended (the “Rexahn 2003 Plan”), that is outstanding and unexercised immediately prior to the Effective Time, will survive the closing of the merger in accordance with its terms.

The Exchange Ratio formula in the Merger Agreement is subject to adjustment based on Rexahn’s net cash balance (the “Parent Cash Amount”) on the Anticipated Closing Date. For example, if the Parent Cash Amount is $0, which is the minimum Parent Cash Amount that Rexahn is required to deliver on the Anticipated Closing Date to consummate the merger, then immediately following the Effective Time, Rexahn Stockholders would own approximately 11.2% of Rexahn common stock, and the former Ocuphire securityholders would own, or hold rights to acquire, approximately 88.8% of Rexahn common stock, in each case calculated on a fully-diluted basis. The calculation of the Exchange Ratio under the Merger Agreement and post-closing ownership of Rexahn Stockholders are subject to adjustment based on an assumed value of Rexahn at closing based on Rexahn’s Parent Cash Amount as of the Anticipated Closing Date. To the extent the Parent Cash Amount falls below $3.2 million or exceeds $6.0 million, Rexahn’s assumed value would be reduced or increased by $150,000 for every $100,000 below or above the thresholds referenced. According to the terms of the Merger Agreement, if the Parent Cash Amount on the Anticipated Closing Date is between $3.2 million and $6.0 million, then immediately following the consummation of the merger, Rexahn Stockholders would own approximately 14.3% of Rexahn common stock, and the former Ocuphire securityholders would own, or hold rights to acquire, approximately 85.7% of Rexahn common stock, in each case, calculated on a fully-diluted basis. The adjustments in the Exchange Ratio formula in the Merger Agreement provide for incremental adjustments of $150,000 to the assumed value of Rexahn for every $100,000 that the Parent Cash Amount is less than $3.2 million or more than $6.0 million, with incremental upward adjustments to the Exchange Ratio to the extent that the Parent Cash Amount is less than $3.2 million (and as a result, Rexahn Stockholders could own less, and Ocuphire securityholders could own more, of the combined company), or incremental downward adjustments to the Exchange Ratio to the extent that the Parent Cash Amount is more than $6.0 million (and as a result, Rexahn Stockholders could own more, and Ocuphire securityholders could own less, of the combined company). Based on Rexahn’s current estimates, Rexahn anticipates delivering a Parent Cash Amount between $0 and $500,000 assuming the Closing occurs by November 14, 2020, which is the end date set forth in the Merger Agreement; however, the final Parent Cash Amount will not be calculated until the Anticipated Closing Date, and may vary significantly depending on, among other things, Rexahn’s ability to control and correctly estimate its operating expenses, expenses relating to Rexahn’s ongoing litigation and the trading price of Rexahn common stock (and its impact on Rexahn’s estimated warrant liabilities, which are deducted from the Parent Cash Amount). As noted

above, if the Parent Cash Amount is $0 on the Anticipated Closing Date, then immediately following the Effective Time, Rexahn Stockholders would own approximately 11.2% of Rexahn common stock, and the former Ocuphire securityholders would own, or hold rights to acquire, approximately 88.8% of Rexahn common stock, in each case calculated on a fully-diluted basis. Under the terms of the Merger Agreement, Rexahn Stockholders’ ownership percentage in the combined company is subject to a floor of approximately 9.1% regardless of the Parent Cash Amount on the Anticipated Closing Date, assuming Ocuphire waives the minimum Parent Cash Amount condition at or prior to the closing of the merger. These ownership percentages give effect to the shares of Ocuphire common stock that will be issued to Investors in the Pre-Merger Financing prior to the Effective Time, but do not account for any additional shares of Rexahn common stock that may be issued to Investors following the Effective Time or shares of Rexahn common stock issuable pursuant to the Investor Warrants issued to Investors after the Effective Time. As a result, Ocuphire securityholders and Rexahn Stockholders could own less of the combined company than currently contemplated. For example, assuming an Exchange Ratio of 4.9398 and Parent Cash Amount of $0, depending on the trading prices of Rexahn common stock on Nasdaq following the closing of the Pre-Merger Financing, the ownership percentage of pre-merger holders of Rexahn common stock could be between 2.0% and 11.2% of the fully-diluted combined company equity securities. Please see the section entitled “The Merger–Merger Consideration and Exchange Ratio” beginning on page 150 of this proxy statement/prospectus/information statement.

Shares of Rexahn common stock are currently listed on the Nasdaq Capital Market under the symbol “REXN.” Rexahn has filed an initial listing application for the combined company with the Nasdaq Capital Market. After completion of the merger, and pending approval of Proposal No. 3 herein, Rexahn will be renamed “Ocuphire Pharma, Inc.” and expects to trade under the symbol “OCUP.” On      , 2020, the last trading day before the date of this proxy statement/prospectus/information statement, the closing sale price of Rexahn common stock was $    per share.

Rexahn is holding a special meeting of its stockholders (the “Rexahn special meeting”) in order to obtain the stockholder approvals necessary to complete the merger and related matters. At the Rexahn special meeting, which will be held at     , Eastern Time, on     , 2020 at            , unless postponed or adjourned to a later date, Rexahn will ask its stockholders to, among other things:

As described in this proxy statement/prospectus/information statement, Ocuphire’s directors, officers, and holders of 5% or more of Ocuphire common stock who in the aggregate own approximately 62.6% of the

outstanding shares of Ocuphire common stock are parties to voting agreements with Rexahn and Ocuphire, pursuant to which such stockholders have agreed to vote their shares in favor of the adoption or approval of certain proposals described in this proxy statement/prospectus/information statement, subject to the terms of the voting agreements.

In addition, following the registration statement on Form S-4, of which this proxy statement/prospectus/information statement is a part, being declared effective by the U.S. Securities and Exchange Commission (the “SEC”) and pursuant to the conditions of the Merger Agreement and the voting agreements, Ocuphire securityholders who are party to the voting agreements will each execute an action by written consent of Ocuphire securityholders (the “written consent”) adopting the Merger Agreement, thereby approving the transactions contemplated therein, including the merger. These securityholders hold a sufficient number of shares of Ocuphire common stock to adopt the Merger Agreement. All holders of Ocuphire common stock (“Ocuphire Stockholders”) will have the opportunity to elect to adopt the Merger Agreement, thereby approving the merger and related transactions, by signing and returning to Ocuphire a written consent.

After careful consideration, the Rexahn board of directors (the “Rexahn Board”) has (i) determined that the merger and all related transactions contemplated by the Merger Agreement are fair to, advisable and in the best interests of Rexahn and its stockholders, (ii) approved and declared advisable the Merger Agreement and the transactions contemplated therein and (iii) determined to recommend, upon the terms and subject to the conditions set forth in the Merger Agreement, that the Rexahn Stockholders vote “FOR” each of the proposals described in this proxy statement/prospectus/information statement.

After careful consideration, Ocuphire’s board of directors (the “Ocuphire Board”) has (i) determined that the merger and all related transactions contemplated by the Merger Agreement are fair to, advisable and in the best interests of Ocuphire and its stockholders, (ii) approved and declared advisable the Merger Agreement and the transactions contemplated therein and (iii) determined to recommend, upon the terms and subject to the conditions set forth in the Merger Agreement, that its stockholders vote to approve the Merger Agreement and the transactions contemplated therein. The Ocuphire Board recommends that Ocuphire’s stockholders sign and return the written consent, indicating their (i) adoption and approval of the Merger Agreement and the transactions contemplated therein, (ii) adoption and approval of an amendment of Ocuphire’s certificate of incorporation to increase the authorized shares of Ocuphire common stock, (iii) acknowledgement that the approval given for the Merger Agreement is irrevocable and that the stockholder is aware of such stockholder’s appraisal rights under Section 262 of the General Corporation Law of the State of Delaware (“DGCL”), and (iv) acknowledgement that by its approval of the merger it is not entitled to appraisal rights with respect to its shares in connection with the merger and thereby waives any rights to receive payment of the fair value of its capital stock under the DGCL.

On behalf of the board of directors (the “Rexahn Board”) of Rexahn Pharmaceuticals, Inc., a Delaware corporation (“Rexahn”), we are pleased to deliver this proxy statement/prospectus/information statement for a special meeting of stockholders of Rexahn (the “Rexahn special meeting”) and for the proposed transactions between Rexahn and Ocuphire Pharma, Inc., a Delaware corporation (“Ocuphire”), pursuant to which Razor Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Rexahn (“Merger Sub”), will merge with and into Ocuphire, with Ocuphire surviving as a wholly owned subsidiary of Rexahn (the “merger”). The Rexahn special meeting will be held on    , 2020 at    Eastern Time, at    for the following purposes:

The Rexahn Board has fixed    , 2020 as the record date for the determination of stockholders entitled to notice of, and to vote at, the Rexahn special meeting and any adjournment or postponement thereof (the

“Record Date”). Only holders of record of shares of Rexahn common stock at the close of business on the Record Date are entitled to notice of, and to vote at, the Rexahn special meeting. At the close of business on the Record Date, Rexahn had     shares of common stock outstanding and entitled to vote.

Your vote is important. The affirmative vote of a majority in interest of the holders of Rexahn common stock present in person or by proxy at the Rexahn special meeting and entitled to vote on the matter is required for approval of Proposal Nos. 1, 4, 5 and 6. The affirmative vote of the holders of a majority of the shares of Rexahn common stock outstanding on the Record Date for the Rexahn special meeting and entitled to vote on the matter is required for approval of Proposal Nos. 2 and 3.

Proposal No. 1 is conditioned upon the approval of Proposal No. 2, and the merger cannot be consummated without the approval of Proposal Nos. 1 and 2. Proposal Nos. 3 and 4 are conditioned upon the consummation of the merger. If the merger is not completed or the stockholders do not approve Proposal No. 3, Rexahn will not change its name to “Ocuphire Pharma, Inc.” If the merger is not completed or the stockholders do not approve Proposal No. 4, the Ocuphire 2020 Plan will not become effective. Proposal No. 5 is conditioned upon Proposal Nos. 1 and 2. Proposal Nos. 1 and 5 are not conditioned on Proposal No. 3 or Proposal No. 4 being approved, and Proposal No. 2 is not conditioned on the approval of any other proposal.

Even if you plan to attend the Rexahn special meeting in person, Rexahn requests that you sign and return the enclosed proxy to ensure that your shares will be represented at the Rexahn special meeting if you are unable to attend.

THE REXAHN BOARD HAS DETERMINED AND BELIEVES THAT EACH OF THE PROPOSALS OUTLINED ABOVE IS ADVISABLE TO, AND IN THE BEST INTERESTS OF, REXAHN AND ITS STOCKHOLDERS AND HAS APPROVED EACH SUCH PROPOSAL. THE REXAHN BOARD RECOMMENDS THAT REXAHN STOCKHOLDERS VOTE “FOR” EACH SUCH PROPOSAL.

Rexahn is closely monitoring developments related to COVID-19. It could become necessary or desirable for Rexahn to change the date, time, location and/or means of holding the Rexahn special meeting (including by means of remote communication). If such a change is made, Rexahn will announce the change in advance, and details on how to participate will be issued by press release, posted on Rexahn’s website and filed as additional proxy materials.

This proxy statement/prospectus/information statement, which forms part of a registration statement on Form S-4 filed with the SEC by Rexahn (File No. 333-239702), constitutes a prospectus of Rexahn under Section 5 of the Securities Act of 1933, as amended, (the “Securities Act”), with respect to the shares of Rexahn common stock to be issued pursuant to the Merger Agreement. This document also constitutes a notice of meeting and a proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), with respect to the Rexahn special meeting, at which Rexahn stockholders will be asked to consider and vote on, among other matters, a proposal to approve the issuance of shares of Rexahn common stock pursuant to the Merger Agreement.

No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this proxy statement/prospectus/information statement. This proxy statement/prospectus/information statement is dated    , 2020. The information contained in this proxy statement/prospectus/information statement is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies.

This proxy statement/prospectus/information statement does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

The information concerning Rexahn contained in this proxy statement/prospectus/information statement or incorporated by reference has been provided by Rexahn, and the information concerning Ocuphire contained in this proxy statement/prospectus/information statement has been provided by Ocuphire.

References to “Rexahn” and “Ocuphire” in this proxy statement/prospectus/information statement refer to Rexahn Pharmaceuticals, Inc. and Ocuphire Pharma, Inc., respectively. References to the “combined company” refer to Rexahn and its wholly owned subsidiary, Ocuphire, after the merger. Except as otherwise noted, references to “we,” “us” or “our” refer to both Rexahn and Ocuphire. References to “Merger Sub” refer to Razor Merger Sub, Inc., a newly formed, wholly owned subsidiary of Rexahn.

References to the “Merger Agreement” refer to that certain agreement and plan of merger and reorganization dated as of June 17, 2020, among Rexahn, Merger Sub and Ocuphire, as amended from time to time, including by the First Amendment to Agreement and Plan of Merger and Reorganization dated June 29, 2020. References to the “merger” refer to the merger of Merger Sub with and into Ocuphire, with Ocuphire surviving as the surviving entity and as a wholly owned subsidiary of Rexahn as contemplated under the Merger Agreement.

company is subject to a floor of approximately 9.1% regardless of the Parent Cash Amount on the Anticipated Closing Date, assuming Ocuphire waives the minimum Parent Cash Amount condition at or prior to Closing. If the Rexahn’s estimated warrant liabilities rise due to an increase in the market price of Rexahn common stock, or Rexahn’s cash decreases for any other reason (including, for example, due to the ongoing litigation related to the merger) then Rexahn may be unable to satisfy the minimum Parent Cash Amount requirement of $0. Even if Ocuphire waives the minimum Parent Cash Amount requirement, Rexahn Stockholders would own significantly less of the combined company than currently estimated. Further, these ownership percentages give effect to the shares of Ocuphire common stock that will be issued to Investors in the Pre-Merger Financing prior to the Effective Time, but do not account for any additional shares of Rexahn common stock that may be issued to Investors following the Effective Time or shares of Rexahn common stock issuable pursuant to the Investor Warrants issued to Investors after the Effective Time. As a result, Ocuphire Securityholders and Rexahn Stockholders could own less of the combined company than currently contemplated. For example, assuming an Exchange Ratio of 4.9398 and Parent Cash Amount of $0, if the average of the five lowest volume-weighted average trading prices of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing is equal to $0.2715 or lower, then the pre-merger holders of Rexahn common stock would own approximately 2.0% of the fully-diluted combined company equity securities. Please see the section entitled “The Merger–Merger Consideration and Exchange Ratio” beginning on page 150 of this proxy statement/prospectus/information statement.

If the combined company is unable to realize the full strategic and financial benefits currently anticipated from the merger, Rexahn Stockholders and Ocuphire Stockholders will have experienced substantial dilution of their ownership interests in their respective companies, including as a result of the Pre-Merger Financing, without receiving any commensurate benefit, or only receiving part of the commensurate benefit to the extent the combined company is able to realize only part of the strategic and financial benefits currently anticipated from the merger and the Pre-Merger Financing.

The Investor Warrants will be issued on the tenth trading day following the merger, will be exercisable immediately upon issuance and contain price-based adjustment provisions, pursuant to which the number of shares of the combined company’s common stock that are issuable upon exercise of the Investor Warrants may be adjusted upward based upon the volume weighted average trading price of the combined organization’s common stock after closing and in the event of certain dilutive issuances by the combined company. The circumstances under which the number of shares of the combined company’s common stock issuable upon exercise of the Investor Warrants may be adjusted upward are set forth in the Investor Warrants and described in the sections entitled “Agreements Related to the Merger − Series A Warrants” and “Agreements Related to the Merger − Series B Warrants” in this proxy statement/prospectus/information statement.

If the adjustment provisions in the Investor Warrants are triggered, a substantial number of additional shares of the combined company’s common stock may become issuable upon exercise of the Investor Warrants, potentially increasing the impact of any subsequent exercise of the Investor Warrants and resale of the shares issuable pursuant thereto.

For illustrative purposes, what follows are four potential scenarios of the dilution that stockholders in the combined company may face as a result of the Pre-Merger Financing as of the warrant closing date, assuming different market prices of the Rexahn common stock on the Nasdaq Capital Market. The maximum amount of shares of Rexahn common stock that could be issuable upon the exercise of the Investor Warrants is the same amount whether determined on the warrant closing date or on any Reset Date, due to the application of the Floor Price on all such dates.

Based on a sample Exchange Ratio of 4.9398, and Ocuphire and Rexahn capitalization as of August 10, 2020, the number of shares of Rexahn common stock to be issued to the Investors at the Effective Time in exchange for the Initial Shares (the “Converted Initial Shares”) would be 5,650,558, resulting in an effective price per share (based on the aggregate purchase price of $21,150,000) of approximately $3.74. The sample Exchange Ratio of 4.9398 assumes (i) Rexahn’s and Ocuphire’s capitalization as of August 10, 2020, (ii) the

Ocuphire convertible notes converted on August 10, 2020, and (iii) Rexahn has a Parent Cash Amount of $0. Different sample Exchange Ratios used elsewhere in this proxy statement/prospectus/information statement have different underlying assumptions that vary based on when such assumptions were made. For example, the sample Exchange Ratio used in the opinion of Oppenheimer attached as Annex E hereto assumed (i) Rexahn’s and Ocuphire’s capitalization as of June 17, 2020, (ii) the Ocuphire convertible notes converted on June 17, 2020, and (iii) Rexahn would deliver a Parent Cash Amount of $720,000. The Exchange Ratio formula is described in more detail in the Merger Agreement and in the section entitled “The Merger—Merger Consideration and Exchange Ratio” of this proxy statement/prospectus/information.

In addition, 16,951,674 shares of Rexahn common stock would be issued to the escrow agent at such time in exchange for the Additional Shares (the “Converted Additional Shares”). Further, the Floor Price (as defined in the section entitled “Prospectus Summary - Pre-Merger Financing”) would be approximately $0.2308 per share.

Under the terms of the Securities Purchase Agreement, if the average of the five lowest volume-weighted average trading prices of a share of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing multiplied by 85% is less than $3.74 (the effective price per share of the Initial Shares), then the Investors will be entitled to receive a combination of Converted Additional Shares and Investor Warrants.

If on the warrant closing date, the average of the five lowest volume-weighted average trading prices of a share of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing is equal to $4.40 (85% of which is $3.74) or more, then no Converted Additional Shares would be deliverable to the Investors from escrow, all of the outstanding Converted Additional Shares held by the escrow agent on such date would be returned to and cancelled by the combined company, the Series A Warrants would be exercisable for 5,650,558 shares with an exercise price of approximately $4.49 per share and the Series B Warrants would be exercisable for zero shares, with both warrants subject to Resets (as defined in the section entitled “Prospectus Summary − Pre-Merger Financing”) on subsequent Reset Dates (as defined in the section entitled “Prospectus Summary − Pre-Merger Financing”). In such case, when excluding the Series A Warrants, the pre-merger holders of Rexahn common stock would own approximately 11.2% of the fully-diluted combined company equity securities, the pre-merger holders of Ocuphire common stock (not including the Investors) would own approximately 73.8% of such amount and the Investors would own approximately 15.0% of such amount. Taking into account the shares of Rexahn common stock underlying the Series A Warrants, such percentages would be approximately 9.8%, 64.1% and 26.1%, respectively.

If on the warrant closing date the average of the five lowest volume-weighted average trading prices of a share of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing is equal to $3.00 (85% of which is $2.55), then 2,643,560 Converted Additional Shares would be deliverable to the Investors from escrow, 14,308,114 of the remaining Converted Additional Shares in escrow on such date would be returned to and cancelled by the combined company, the Series A Warrants would be exercisable for 8,294,118 shares with an exercise price of $3.06 per share and the Series B Warrants would be exercisable for zero shares, with both warrants subject to Resets on subsequent Reset Dates. In such case, when excluding the Series A Warrants, the pre-merger holders of Rexahn common stock would own approximately 10.5% of the fully-diluted combined company equity securities, the pre-merger holders of Ocuphire common stock would own approximately 68.9% and the Investors would own approximately 20.6% of such amount. Taking into account the shares of Rexahn common stock underlying the Series A Warrants, such percentages would be approximately 8.7%, 57.2% and 34.1% respectively.

If on the warrant closing date the average of the five lowest volume-weighted average trading prices of a share of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing is equal to $1.50 (85% of which is approximately $1.28), then 10,937,678 of the Converted Additional Shares would be deliverable to the Investors from escrow, 6,013,996 Converted Additional

Shares would be returned to and cancelled by the combined company, the Series A Warrants would be exercisable for 16,588,236 shares with an exercise price of approximately $1.53 per share and the Series B Warrants would be exercisable for zero shares, with both warrants subject to Resets on subsequent Reset Dates. In such case, when excluding the Series A Warrants, the pre-merger holders of Rexahn common stock would own approximately 8.7% of the fully-diluted combined company equity securities, the pre-merger holders of Ocuphire common stock (not including the Investors) would own approximately 57.2% of such amount and the Investors would own approximately 34.1% of such amount. Taking into account the shares of Rexahn common stock underlying the Series A Warrants, such percentages would be approximately 6.5%, 42.6% and 50.9%, respectively.

If on the warrant closing date the average of the five lowest volume-weighted average trading prices of a share of Rexahn common stock on Nasdaq during the first ten trading days immediately following the closing of the Pre-Merger Financing is equal to $0.2715 (85% of which is approximately $0.2308, the estimated Floor Price) or lower, then all 16,951,674 of the Converted Additional Shares would be deliverable to the Investors from escrow, no Converted Additional Shares would be returned to and cancelled by the combined company, the Series A Warrants would be exercisable for 91,637,782 shares with an exercise price of approximately $0.28 per share and the Series B Warrants would be exercisable for 69,035,550 shares with an exercise price of $0.0001 per share, this being the maximum amount issuable under such warrants, and therefore no increases upon subsequent Resets while the Floor Price still applies. In such case, when including the Series B Warrants but excluding the Series A Warrants, the pre-merger holders of Rexahn common stock would own approximately 3.4% of the fully-diluted combined company equity securities, the pre-merger holders of Ocuphire common stock (not including the Investors) would own approximately 22.5% of such amount and the Investors would own approximately 74.1% of such amount. Taking into account the shares of Rexahn common stock underlying the Series A Warrants, such percentages would be approximately 2.0%, 12.9% and 85.1%, respectively.

Under the Merger Agreement, Parent Cash Amount is reduced by, among other things, the Estimated Warrant Amount to be calculated approximately 10 days prior to Closing in accordance with the terms of the Merger Agreement. The Estimated Warrant Amount will be impacted by, among other things, the trading price of a share of Rexahn common stock, with such Estimated Warrant Amount increasing as the trading price increases and decreasing as the trading price decreases. Under the Merger Agreement, Rexahn is permitted to exchange or modify outstanding Rexahn Warrants for (i) newly issued shares of Rexahn common stock without obtaining Ocuphire’s prior consent and (ii) Replacement Warrants or in-the-money Rexahn securities with the prior consent of Ocuphire. In addition, the Parent Cash Amount will be increased by $1.00 for each share of Rexahn common stock underlying any outstanding Rexahn warrant that is exchanged and terminated in exchange for a newly issued share of Rexahn common stock between the date of execution of the Merger Agreement and the Effective Time. Rexahn’s issuance of newly issued shares of Rexahn common stock, Replacement Warrants and/or other Rexahn securities would have a dilutive effect on Rexahn Stockholders at the Effective Time. For example, any newly issued shares of Rexahn common stock and in-the-money Replacement Warrants will be counted toward Rexahn’s fully diluted shares outstanding for purposes of calculating the Exchange Ratio, and one-half of any out-of-the-money Replacement Warrants will be counted toward such amount. A Replacement Warrant will be out-of-the-money if its exercise price is equivalent to or greater than $2.5025, and will be in-the-money if its exercise price is less than such amount. On July 31, 2020, Rexahn entered into a Warrant Exchange Agreement (the “Exchange Agreement”) with Armistice Capital Master Fund Ltd. (“Armistice”). Rexahn previously issued to Armistice (a) a warrant to purchase 160,257 shares of Rexahn common stock pursuant to the offering described in Rexahn’s Current Report on Form 8-K filed with the SEC on October 19, 2018 (the “2018 Warrant”), and (b) a warrant to purchase 208,334 shares of Rexahn common stock pursuant to the offering described in Rexahn’s Current Report on Form 8-K filed with the SEC on January 25, 2019 (the “2019 Warrant” and together with the 2018 Warrant, the “Armistice Warrants”). Pursuant to the Exchange Agreement, on August 3, 2020, the Company is issued to Armistice an aggregate of 215,000 shares of Rexahn common stock in exchange for the surrender and cancellation of the Armistice Warrants.

The Merger Agreement has set the calculation of the Exchange Ratio for the Ocuphire capital stock, and the Exchange Ratio is based on the fully-diluted capitalization of Ocuphire and Rexahn, in each case immediately prior to the Closing as described in the section entitled “The Merger—Merger Consideration and Exchange Ratio.”

The Merger Agreement does not include a price-based termination right. Therefore, if before the completion of the merger the market price of Rexahn common stock declines from the market price on the date of the Merger Agreement, then Ocuphire Stockholders could receive merger consideration with substantially lower value than the value of such merger consideration on the date of the Merger Agreement. Similarly, if before the completion of the merger the market price of Rexahn common stock increases from the market price of Rexahn common stock on the date of the Merger Agreement, then Ocuphire Stockholders could receive merger consideration with substantially greater value than the value of such merger consideration on the date of the Merger Agreement. Because the Exchange Ratio does not adjust as a direct result of changes in the market price of Rexahn common stock (other than to the extent such changes impact the calculation of the Parent Cash Amount due to changes in liabilities associated with Rexahn Warrants), changes in the market price of Rexahn common stock will change the value of the total merger consideration payable to Ocuphire Stockholders pursuant to the Merger Agreement.

Stock price changes may result from a variety of factors, including, but not limited to, changes in Ocuphire’s or Rexahn’s respective businesses, operations and prospects, reductions or changes in U.S. government spending or budgetary policies, market assessments of the likelihood that the merger will be completed, interest rates, federal, state, and local legislation, governmental regulation, legal developments in the industry segments in which Ocuphire or Rexahn operate, the timing of the merger, and general market, industry and economic conditions, including pandemics and other public health emergencies. The COVID-19 pandemic, in particular, has introduced unusually high levels of volatility into financial and stock markets, and may affect the value of Rexahn common stock.

If the merger is not completed and the Merger Agreement is terminated under certain circumstances, Rexahn or Ocuphire may be required to pay the other party a termination fee of $750,000, and in some circumstances Ocuphire may be required to reimburse Rexahn’s expenses up to a maximum of $750,000. Even if a termination fee or expenses of the other party are not payable in connection with a termination of the Merger Agreement, each of Rexahn and Ocuphire will have incurred significant fees and expenses, which must be paid whether or not the merger is completed. Further, if the merger is not completed, it could significantly harm the market price of Rexahn common stock and raise serious doubts as to its ability to continue as an entity.

In addition, if the Merger Agreement is terminated and the Rexahn Board or Ocuphire Board determines to seek another business combination, there can be no assurance that either Rexahn or Ocuphire will be able to find a partner and close an alternative transaction on terms that are as favorable or more favorable than the terms set forth in the Merger Agreement. See the section entitled “Risk Factors—If the merger is not completed, Rexahn may not be able to otherwise source adequate liquidity to fund its operations, meet its obligations, and continue as a going concern. The Rexahn Board may decide to pursue a dissolution and liquidation of Rexahn. In such an event, there can be no assurances as to the amount or timing of available cash left, if any, to distribute to its stockholders after paying its debts and other obligations and setting aside funds for reserves” in this proxy statement/prospectus/information statement.

Before the merger can be completed, the Rexahn Stockholders must approve, among other things, the issuance of Rexahn common stock to Ocuphire Stockholders pursuant to the Merger Agreement and the resulting change in control from the merger, and Ocuphire Stockholders must approve the Merger Agreement and the

transactions contemplated thereby. Failure to obtain the required stockholder approvals may result in a material delay in, or the abandonment of, the merger. Any delay in completing the merger may materially adversely affect the timing and benefits that are expected to be achieved from the merger.

The Merger Agreement provides that either Rexahn or Ocuphire can refuse to complete the merger if there is a material adverse change affecting the other party between June 17, 2020, the date of the Original Merger Agreement, and the Closing. However, certain types of changes do not permit either party to refuse to complete the merger, even if such change could be said to have a material adverse effect on Rexahn or Ocuphire, including:

If adverse changes occur and Rexahn and Ocuphire still complete the merger, the market price of the combined company’s common stock may suffer. This in turn may reduce the value of the merger to the stockholders of Rexahn, Ocuphire or both.

Certain officers and directors of Rexahn and Ocuphire participate in arrangements that provide them with interests in the merger that are different from the interests of the respective stockholders of Rexahn and Ocuphire, including, among others, the continued service as an officer or director of the combined company, severance benefits, the acceleration of stock option vesting, continued indemnification and the potential ability to sell an increased number of shares of common stock of the combined company in accordance with Rule 144 under the Securities Act. For example, Rexahn has entered into an employment agreement with its President and Chief Executive Officer that will result in the receipt by such officer of cash severance payments and other benefits upon an eligible termination of employment of such officer’s employment following the Closing. In addition, Mr. Rodgers, a member of the Rexahn Board, is expected to continue as a member of the Rexahn Board following the merger. Mr. Rodgers, along with the rest of the expected members of the Rexahn Board following the merger, has committed to invest in the Pre-Merger Financing. Mr. Rodgers’ investment is for $100,000 in the Pre-Merger Financing. The compensation arrangements with Rexahn’s officers and directors are discussed in greater detail in the sections entitled “The Merger—Interests of Rexahn Directors and Executive Officers in the Merger” and “Rexahn Executive Compensation-Director Compensation” in this proxy statement/prospectus/information statement.

These interests, among others, may influence the officers and directors of Rexahn and Ocuphire to support or approve the merger. For more information concerning the interests of Rexahn’s and Ocuphire’s respective officers and directors, see the sections entitled “The Merger—Interests of Rexahn Directors and Executive Officers in the Merger” and “The Merger—Interests of Ocuphire Directors and Executive Officers in the Merger” in this proxy statement/prospectus/information statement.

The market price of Rexahn common stock may decline as a result of the merger for a number of reasons, including if:

If the proposed merger is completed, the current securityholders of Rexahn and Ocuphire will own a smaller percentage of the combined company than their ownership in their respective companies prior to the merger. Accordingly, the issuance of shares of Rexahn common stock to Ocuphire Stockholders in the merger will reduce significantly the relative voting power of each share of Rexahn common stock held by its current stockholders and will reduce the relative voting power of each share of Ocuphire common stock held by its current stockholders. Consequently, Rexahn Stockholders as a group and Ocuphire Stockholders as a group will have less influence over the management and policies of the combined company after the merger than prior to the merger.

In addition, the board of directors for the post-merger combined company is expected to be comprised of seven directors, one of whom is expected to be Richard J. Rodgers, a current member of the Rexahn Board, and the remaining six directors are expected to include existing Ocuphire board members and an additional director designated by Ocuphire. Consequently, securityholders of both Rexahn and Ocuphire will be able to exercise less influence over the management and policies of the combined company following the Closing than they currently exercise over the management and policies of their respective companies.

The combined company may be required to raise additional funds sooner than currently planned. If either or both of Rexahn or Ocuphire hold less cash at the time of the Closing than the parties currently expect, the combined company will need to raise additional capital sooner than expected. Additional financing may not be available to the combined company when it needs it or may not be available on favorable terms. To the extent that the combined company raises additional capital by issuing equity securities, such an issuance may cause significant dilution to the combined company’s stockholders’ ownership and the terms of any new equity securities may have preferences over the combined company’s common stock. Any debt financing the combined company enters into may involve covenants that restrict its operations. These restrictive covenants may include limitations on additional borrowing and specific restrictions on the use of the combined company’s assets, as well as prohibitions on its ability to create liens, pay dividends, redeem its stock or make investments. In addition, if the combined company raises additional funds through licensing, partnering or other strategic arrangements, it may be necessary to relinquish rights to some of the combined company’s technologies or product candidates and proprietary rights, or grant licenses on terms that are not favorable to the combined company.

Furthermore, provisions in the Securities Purchase Agreement and related documents may deter or prevent the combined company from raising additional capital to fund the company as and when needed. For example, the Securities Purchase Agreement restricts Rexahn from filing a registration statement or any amendment or supplement thereto, causing any registration statement to be declared effective by the SEC, or granting any registration rights, in each case subject to certain limited exceptions, until the date that is 90 days after the earlier of (i) such time as all of the shares of Rexahn common stock issued or issuable in the Pre-Merger Financing may be sold without restriction or limitation pursuant to Rule 144, and (ii) the date that is six months following the Closing; provided that in the event Rexahn shall fail to satisfy any condition set forth in Rule 144(i)(2) under the

Securities Act (a “Public Information Failure”), such date shall be such later date on which the Public Information Failure is cured and no longer prevents the investors from selling all shares of Rexahn common stock issued or issuable in the Pre-Merger Financing (the 90th date after such earlier date, the “Trigger Date”).

In addition, pursuant to the Securities Purchase Agreement, until 240 calendar days following the closing of the Pre-Merger Financing, subject to certain exceptions, neither Ocuphire nor Rexahn may (i) offer, sell, grant any option to purchase, or otherwise dispose of any of its or its subsidiaries’ debt, equity or equity equivalent securities (any such offer, sale, grant, disposition or announcement being referred to as a “Subsequent Placement”), or (ii) be party to any solicitations, negotiations or discussions with regard to the foregoing.

Additionally, for one year following the closing of the Pre-Merger Financing, Ocuphire, Rexahn and each of their subsidiaries will be prohibited from effecting or entering into an agreement to effect any Subsequent Placement involving a transaction in which Ocuphire, Rexahn or any of their subsidiaries (i) issues or sells any stock or securities convertible into or exercisable or exchangeable for Ocuphire common stock or Rexahn common stock (“Convertible Securities”) either (a) at a conversion, exercise or exchange rate or other price that is based upon and/or varies with the trading prices of or quotations for the shares of Ocuphire common stock or Rexahn common stock at any time after the initial issuance of such Convertible Securities, or (b) with a conversion, exercise or exchange price that is subject to being reset at some future date after the initial issuance of such Convertible Securities or upon the occurrence of specified or contingent events directly or indirectly related to the business of Ocuphire or Rexahn or the market for Ocuphire common stock or Rexahn common stock, other than pursuant to a customary “weighted average” anti-dilution provision or (ii) enters into any agreement (including, without limitation, an equity line of credit or an “at-the-market” offering) whereby Ocuphire, Rexahn or any of their subsidiaries may sell securities at a future determined price (other than standard and customary “preemptive” or “participation” rights); provided, that Rexahn will be permitted to consummate “at the market” offerings at any time after the later of (x) the date that is nine months after the closing date of the Pre-Merger Financing and (y) the Trigger Date.

These restrictive covenants and other provisions in the Pre-Merger Financing documents could deter or prevent the combined company from raising additional capital as and when needed. The combined company’s failure to raise capital as and when needed would have a negative effect on its financial condition and its ability to develop and commercialize its pipeline and otherwise pursue the combined company’s business strategy and the combined company may be unable to continue as a going concern.

Covenants in the Merger Agreement impede the ability of Rexahn and Ocuphire to make acquisitions, subject to certain exceptions relating to fiduciary duties, as set forth below, or to complete other transactions that are not in the ordinary course of business pending completion of the merger. As a result, if the merger is not completed, the parties may be at a disadvantage to their competitors during such period. In addition, while the Merger Agreement is in effect, each party is generally prohibited from soliciting, initiating, encouraging or entering into certain extraordinary transactions, such as a merger, sale of assets, or other business combination outside the ordinary course of business with any third party, subject to certain exceptions relating to fiduciary duties. Any such transactions could be favorable to such party’s stockholders.

The terms of the Merger Agreement prohibit each of Rexahn and Ocuphire from soliciting alternative takeover proposals or cooperating with persons making unsolicited takeover proposals, except in limited circumstances when such party’s board of directors determines in good faith that an unsolicited alternative takeover proposal is or is reasonably likely to lead to a superior takeover proposal and that failure to cooperate with the proponent of the proposal would be reasonably likely to be inconsistent with the applicable board’s fiduciary duties. Any such transactions could be favorable to such party’s stockholders. In addition, if Rexahn terminates the Merger Agreement under certain circumstances, including terminating because of a decision of Rexahn to enter into definitive agreement with respect to a superior offer, Rexahn would be required to pay a

termination fee of $750,000 to Ocuphire. This termination fee described above may discourage third parties from submitting alternative takeover proposals to Rexahn Stockholders.

The outstanding common stock of Ocuphire is privately held and is not traded in any public market. The lack of a public market makes it extremely difficult to determine the fair market value of Ocuphire. Because the percentage of Rexahn common stock to be issued to Ocuphire Stockholders was determined based on negotiations between the parties, it is possible that the value of Rexahn common stock to be received by Ocuphire Stockholders will be less than the fair market value of Ocuphire, or Rexahn may pay more than the aggregate fair market value for Ocuphire.

Even if the transactions contemplated by the Merger Agreement are approved by Rexahn Stockholders and Ocuphire Stockholders, certain other specified conditions set forth in the Merger Agreement must be satisfied or waived to complete the merger, including approval from Nasdaq to maintain the listing of the Rexahn common stock on the Nasdaq Capital Market following the merger and to list the shares of Rexahn common stock being issued in the merger. These conditions are set forth in the Merger Agreement and described in the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” in this proxy statement/prospectus/information statement. Rexahn and Ocuphire cannot assure you that all of the conditions will be satisfied or waived. If the conditions are not satisfied or waived, the merger will not occur or will be delayed, and Rexahn and Ocuphire each may lose some or all of the intended benefits of the merger.

The current expectation is that the combined company will retain its future earnings, if any, to fund the development and growth of the combined company’s business. As a result, capital appreciation, if any, of the common stock of the combined company will be your sole source of gain, if any, for the foreseeable future.

If existing stockholders of Rexahn and Ocuphire sell, or indicate an intention to sell, substantial amounts of the combined company’s common stock in the public market after the merger, the trading price of the common stock of the combined company could decline. Using Rexahn’s capitalization as of August 10, 2020, taking into account the consummation of the Pre-Merger Financing and an assumed Exchange Ratio of 4.9398, the combined company is expected to have outstanding a total of approximately 48,817,796 shares of common stock (prior to giving effect to the proposed Rexahn Reverse Stock Split, and including the Converted Additional Shares held in escrow). Not all shares of Rexahn common stock will be freely tradable, without restriction, in the public market. For example, approximately 16,951,674 shares will initially be Converted Additional Shares held in escrow, and an aggregate of 11,437,288 shares of the combined company’s common stock will be subject to the lock-up agreements required under the Securities Purchase Agreement or Merger Agreement as of the Closing.

In addition, using the assumptions set forth in the illustrative scenarios in the section entitled “Agreements Related to the Merger—Pre-Merger Financing,” and subject to the terms of the Leak-Out Agreements described in such section, assuming that (i) all of the Converted Additional Shares are delivered to the Investors from escrow pursuant to the Securities Purchase Agreement and (ii) the Series B Warrants are initially exercisable or otherwise Reset to the maximum extent subject to the Floor Price, the Investors would hold (a) an aggregate of 22,602,232 shares of Rexahn common stock and (b) Series B Warrants exercisable for an aggregate of 69,035,550 shares of Rexahn common stock, at an exercise price of $0.0001 per share.

One of the conditions to the obligations of Rexahn under the Merger Agreement is that on or immediately prior to the Closing, Ocuphire consummate the Pre-Merger Financing whereby Ocuphire receives gross proceeds of no less than $20,000,000. No assurance can be given that all of the conditions to the consummation of the

Pre-Merger Financing condition will be satisfied, or that Ocuphire will be able to satisfy the Pre-Merger Financing condition. If the Pre-Merger Financing is not consummated, and if Rexahn is not otherwise willing to waive the Pre-Merger Financing condition, the parties will not be able to consummate the merger.

On July 31, 2020, a putative stockholder class action was filed in the Court of Chancery of the State of Delaware styled Stahlman v. Rexahn Pharmaceuticals, Inc., et al., Case No. 2020-0639. Additionally, on August 3, 2020, a putative stockholder class action was filed in the United States District Court for the District of Delaware styled Thompson v. Rexahn Pharmaceuticals, Inc., et al., Case No. 1:20-cv-01036-UNA (D. Del). On August 7, 2020 and August 17, 2020, putative stockholder class actions were filed in the United States District Court for the Southern District of New York styled, respectively, Manes v. Rexahn Pharmaceuticals, Inc., et al., Case No. 1:20-cv-06227 (S.D.N.Y.) and Talsma v. Rexahn Pharmaceuticals, Inc., et al Case No. 1:20-cv-06541 (S.D.N.Y). On August 18, 2020, a putative stockholder class action was filed in the United States District Court for the Eastern District of New York styled Juilfs v. Rexahn Pharmaceuticals, Inc., et al Case No. 1:20-cv-03780 (E.D.N.Y.) (together with the Stahlman, Thompson, Manes and Talsma actions, the “Stockholder Actions”). The Stockholder Actions assert claims against Rexahn and the Individual Defendants.

The Stahlman and Manes complaints allege that the Individual Defendants breached their fiduciary duties owed to the Rexahn stockholders. The Thompson, Manes, Juilfs and Talsma complaints allege that Rexahn and the Individual Defendants violated Section 14(a) of the Exchange Act, and Rule 14a-9 promulgated thereunder, by failing to disclose in the Initial Registration Statement certain information regarding, among other things, financial projections for Rexahn and Ocuphire, the valuation analyses performed by Rexahn’s financial advisor, Oppenheimer, in support of its fairness opinion and the process leading to the execution of the Merger Agreement. The Thompson, Manes, Juilfs and Talsma complaints also allege that the Individual Defendants violated Section 20(a) of the Exchange Act, as control persons who had the ability to prevent the Initial Registration Statement from being false and misleading. The Stockholder Actions seek, among other things, an injunction preventing consummation of the merger, an award of damages, and an award of costs and expenses, including attorneys’ fees.

Additionally, on August 6, 2020, another party sent a letter to Rexahn’s counsel demanding that Rexahn and the Individual Defendants amend the Initial Registration Statement to provide additional disclosures that the party alleges were improperly omitted from the Initial Registration Statement in violation of Sections 14(a) and 20(a) of the Exchange Act, including certain information regarding financial data and the background and process leading to the execution of the Merger Agreement (the “Demand Letter”).

Rexahn and the Individual Defendants intend to vigorously defend against the Stockholder Actions and the Demand Letter. Additional lawsuits arising out of or relating to the Merger Agreement or the Merger may be filed in the future against Rexahn and Ocuphire. The results of complex legal proceedings are difficult to predict and could delay or prevent the completion of the merger. The existence of litigation relating to the merger could impact the likelihood of obtaining stockholder approval of the merger. Moreover, the pending litigation is, and any future additional litigation could be, time consuming and expensive and could divert management’s attention away from its regular business.

The historical unaudited pro forma condensed combined financial information included elsewhere in this proxy statement/prospectus/information statement has been presented for informational purposes only and is not necessarily indicative of the financial position or results of operations that actually would have occurred had the merger been completed as of the date indicated, nor is it indicative of future operating results or financial position.

One of the purposes of the proposed Rexahn Reverse Stock Split is to increase the per-share market price of the Rexahn common stock. It cannot be assured, however, that the proposed Rexahn Reverse Stock Split will accomplish this objective for any meaningful period of time. While it is expected that the reduction in the number of outstanding shares of Rexahn common stock will proportionally increase the market price of Rexahn common stock, it cannot be assured that the proposed Rexahn Reverse Stock Split will increase the market price of Rexahn common stock by a multiple of the proposed Rexahn Reverse Stock Split ratio, or result in any permanent or sustained increase in the market price of Rexahn common stock, which is dependent upon many factors, including the combined company’s business and financial performance, general market conditions and prospects for future success. Thus, while the stock price of the combined company might meet the continued listing requirements for the Nasdaq Capital Market initially, it cannot be assured that it will continue to do so.

Although the Rexahn Board believes that the anticipated increase in the market price of the combined company’s common stock could encourage interest in its common stock and possibly promote greater liquidity for its stockholders, such liquidity could also be adversely affected by the reduced number of shares outstanding after the proposed Rexahn Reverse Stock Split. The reduction in the number of outstanding shares may lead to reduced trading and a smaller number of market makers for Rexahn common stock.

Should the market price of the combined company’s common stock decline after the proposed Rexahn Reverse Stock Split, the percentage decline may be greater, due to the smaller number of shares outstanding, than it would have been prior to the proposed Rexahn Reverse Stock Split. A reverse stock split may be viewed negatively by the market and, consequently, can lead to a decrease in the combined company’s overall market capitalization. If the per share market price does not increase in proportion to the proposed Rexahn Reverse Stock Split ratio, then the value of the combined company, as measured by its stock capitalization, will be reduced. In some cases, the per-share stock price of companies that have effected reverse stock splits subsequently declined back to pre-reverse split levels, and accordingly, it cannot be assured that the total market value of Rexahn common stock will remain the same after the proposed Rexahn Reverse Stock Split is effected, or that the proposed Rexahn Reverse Stock Split will not have an adverse effect on the price of Rexahn common stock due to the reduced number of shares outstanding after the proposed Rexahn Reverse Stock Split.

While Rexahn has entered into the Merger Agreement with Ocuphire, the Closing may be delayed or may not occur at all and there can be no assurance that the merger will deliver the anticipated benefits Rexahn expects or enhance stockholder value. If the merger is not completed and the Merger Agreement is terminated under certain circumstances, Rexahn may be required to pay Ocuphire a termination fee of $750,000. Even if a termination fee is not payable in connection with a termination of the Merger Agreement, Rexahn will have incurred significant fees and expenses, which must be paid whether or not the merger is completed.

Rexahn believes its cash on hand will be sufficient to cover its cash flow requirements for its current activities for at least the next 12 months from the date its financial statements for the quarterly period ended June 30, 2020 were originally issued, assuming the merger does not close. If for any reason the merger does not

close, Rexahn would need to raise additional capital to continue to fund the further development of its product candidates and its operations thereafter. Rexahn has based its cash sufficiency estimates on its current business plan and its assumptions may prove to be wrong. Rexahn could utilize its available capital resources sooner than it currently expects, and it could need additional funding sooner than currently anticipated. Additionally, the process of advancing early stage product candidates and testing product candidates in clinical trials is costly, and the timing of progress in these clinical trials is uncertain. Even if Rexahn raises sufficient funds and decides to continue the development of its product candidates, its ability to successfully transition to profitability will be dependent upon achieving a level of product sales adequate to support its cost structure. Rexahn cannot assure you that it will ever be profitable or generate positive cash flow from operating activities.

Failure to secure any necessary financing in a timely manner and on favorable terms or the failure of the proposed merger to be consummated in a timely manner would require Rexahn to delay or abandon clinical development plans. If, for any reason, the merger does not close, the Rexahn Board may elect to, among other things, attempt to complete another strategic transaction like the merger, attempt to sell or otherwise dispose of the various assets of Rexahn, resume its research and development activities and continue to operate the business of Rexahn. Any of these alternatives would be costly and time-consuming and would require that Rexahn obtain additional funding. Rexahn expects that it would be difficult to secure financing in a timely manner, on favorable terms or at all. Rexahn can make no assurances that it would be able to obtain additional financing or find a partner and close an alternative transaction on terms that are as favorable or more favorable than the terms set forth in the Merger Agreement or that any such alternatives are possible or would be successful, if pursued. To the extent that Rexahn seeks and is able to raise additional capital through the sale of equity or convertible debt securities, Rexahn Stockholders’ ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect their rights as a common stockholder. Debt financing or preferred equity financing, if available, may involve agreements that include covenants limiting or restricting Rexahn’s ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If Rexahn raises funds through strategic transactions or marketing, distribution, or licensing arrangements with third parties, Rexahn may have to relinquish valuable rights to its technologies, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to it. Even if Rexahn is able to pursue such alternatives, the failure to complete the merger may result in negative publicity and/or a negative impression of Rexahn in the investment community, could significantly harm the market price of Rexahn common stock and may affect Rexahn’s relationship with employees and other partners in the business community.

If the Rexahn Board were to decide to dissolve and liquidate Rexahn’s assets, Rexahn would be required to pay all of its debts and contractual obligations, and to set aside certain reserves for potential future claims, and there can be no assurances as to the amount or timing of available cash left, if any, to distribute to stockholders after paying its debts and other obligations and setting aside funds for reserves. In addition, Rexahn may be subject to litigation or other claims related to a dissolution and liquidation. If a dissolution and liquidation were pursued, the Rexahn Board, in consultation with its advisors, would need to evaluate these matters and make a determination about a reasonable amount to reserve. Accordingly, Rexahn Stockholders would likely lose all or a significant portion of their investment in the event of a liquidation, dissolution or winding up of Rexahn.

Rexahn does not believe that its current expenses are indicative of the costs it may incur in the future in connection with the development and commercialization of any product candidate if it consummates the merger or raises additional capital to continue its operations. Rexahn’s future funding requirements will depend on many factors, including:

Rexahn’s shelf registration statement on Form S-3 expired in July 2020. Even if Rexahn files a new shelf registration statement with the SEC, the amounts available under the shelf registration statement will be significantly limited as long as Rexahn’s public float remains below $75 million, which, given its currently depressed stock price, limits its ability to obtain meaningful funding through a shelf registration statement at this time, although Rexahn could still raise funds through a registration statement on Form S-1 or through private placements.

The right of Rexahn Stockholders to receive any future payment on or derive any value from the CVRs will be contingent solely upon the achievement of the events specified in the CVR Agreement within the time periods specified in the CVR Agreement and the consideration received being greater than the amounts permitted to be retained or deducted by Rexahn under the CVR Agreement. Rexahn may not be able to grant, sell or transfer its rights to Rexahn’s pre-Closing intellectual property during the 10-year period after the Closing, and Rexahn may not receive any future payments pursuant to the BioSense Agreement or HaiChang Agreement after the Closing. If these events are not achieved for any reason within the time periods specified in the CVR Agreement or the consideration received is not greater than the amounts permitted to be retained or deducted by Rexahn, no payments will be made under the CVRs, and the CVRs will expire valueless. Following the Effective Time of the merger, neither Rexahn nor Ocuphire will have any obligation to support the development of any of Rexahn’s pre-Closing product candidates or to undertake any effort or expend any resource to divest or otherwise monetize Rexahn’s pre-Closing intellectual property or to otherwise maximize the likelihood or amount of any CVR payment. Following the Closing, Rexahn may, at any time and in its sole and absolute discretion, discontinue any and all further efforts to develop, divest or otherwise monetize any or all of Rexahn’s pre-Closing intellectual property.

Furthermore, the CVRs will be unsecured obligations of the combined company and all payments under the CVRs, all other obligations under the CVR Agreement and the CVRs and any rights or claims relating thereto will be subordinated in right of payment to the prior payment in full of all current or future senior obligations of the combined company.

The U.S. federal income tax treatment of the CVRs is unclear. There is no legal authority directly addressing the U.S. federal income tax treatment of the receipt of, and payments on, the CVRs, and there can be no assurance that the Internal Revenue Service (“IRS”) would not assert, or that a court would not sustain, a position that could result in adverse U.S. federal income tax consequences to holders of the CVRs.

As discussed in the section entitled “Agreements Related to the Merger—Contingent Value Rights Agreement—Material U.S. Federal Income Tax Consequences of the Receipt of CVRs,” Rexahn intends to treat the issuance of the CVRs as a distribution of property with respect to its stock. In such case, each Rexahn U.S. Holder (as defined on page 183) will be treated as receiving a distribution in an amount equal to the fair market value of the CVRs issued to such Rexahn U.S. Holder on the date of the issuance. This distribution should be treated first as a taxable dividend to the extent of the Rexahn U.S. Holder’s pro rata share of Rexahn’s current or accumulated earnings and profits (as determined for U.S. federal income tax purposes), then as a non-taxable return of capital to the extent of the Rexahn U.S. Holder’s basis in its Rexahn common stock, and finally as capital gain from the sale or exchange of Rexahn common stock with respect to any remaining value. Rexahn currently has negative accumulated earnings and profits and expects no or a small amount of current earnings and profits for the relevant taxable year. Thus, Rexahn expects most or all of this distribution to be treated as

other than a dividend for U.S. federal income tax purposes. However, there is no authority directly addressing whether contingent value rights with characteristics similar to the CVRs should be treated as a distribution of property with respect to the corporation’s stock, a distribution of equity, a “debt instrument” or an “open transaction” for U.S. federal income tax purposes. Further, notwithstanding Rexahn’s position that the receipt of CVRs and the Rexahn Reverse Stock Split are appropriately treated as separate transactions, it is possible that the IRS or a court could determine that the receipt of the CVRs and the Rexahn Reverse Stock Split constitute a single “recapitalization” for U.S. federal income tax purposes. Therefore, no assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to Rexahn’s position, which could result in adverse U.S. federal income tax consequences to holders of the CVRs. The tax consequences of such alternative treatments are described below under the section entitled “Agreements Related to the Merger—Contingent Value Rights Agreement—Material U.S. Federal Income Tax Consequences of the Receipt of CVRs,” beginning on page 182 of this proxy statement/prospectus/information statement.

To date, Rexahn has generated no product revenues and has incurred negative cash flow from operations. Until Rexahn receives approval from the FDA or other regulatory authorities for its product candidates, Rexahn cannot sell its drugs and will not have product revenues. If the merger is not consummated, Rexahn expects to continue to incur significant development and other expenses related to its ongoing operations. Therefore, for the foreseeable future, Rexahn would have to fund all of its operations and capital expenditures from the net proceeds of equity or debt offerings, cash on hand, licensing fees and grants, if any. If Rexahn is not able to raise sufficient funds, Rexahn will have to reduce its research and development activities, and it may be more difficult to develop its pipeline. Rexahn will first reduce research and development activities associated with any preclinical compounds. To the extent necessary, Rexahn will then reduce its research and development activities related to its clinical stage product candidates.

Unforeseen events, difficulties, complications and delays may occur that could cause Rexahn to utilize its existing capital at a faster rate than projected, including the progress of its research and development efforts, the cost and timing of regulatory approvals and the costs of protecting its intellectual property rights. Rexahn may seek additional financing to implement and fund other product candidate development, clinical trial and research and development efforts, including clinical trials for other new product candidates, as well as other research and development projects.

If the merger is not consummated, Rexahn will need additional financing to continue to develop its product candidates, which may not be available on favorable terms, if at all. If Rexahn is unable to secure additional financing in the future on acceptable terms, or at all, Rexahn may be unable to initiate or complete preclinical and clinical trials or obtain approval of its product candidates from the FDA and other regulatory authorities. In addition, Rexahn may be forced to reduce or discontinue product development or product licensing, reduce or forego sales and marketing efforts and forego attractive business opportunities in order to improve its liquidity to enable Rexahn to continue operations. Any additional sources of financing will likely involve the sale of Rexahn’s equity securities or securities convertible into Rexahn’s equity securities, which may have a dilutive effect on Rexahn Stockholders.

Since its inception, Rexahn has incurred significant net losses. Rexahn’s accumulated deficit as of June 30, 2020 and December 31, 2019 was $166,420,604 and $163,322,676, respectively. For the six months ended June 30, 2020 and 2019 and the years ended December 31, 2019 and 2018, Rexahn had net losses of $3,097,928, $4,807,280, $8,635,434 and $14,368,530, respectively. Even if Rexahn succeeds in developing and commercializing one or more of its product candidates, Rexahn expects to incur substantial losses for the foreseeable future and may never become profitable. Rexahn also expects to continue to incur significant operating and capital expenditures, including related to:

Rexahn also expects to continue to experience negative cash flow for the foreseeable future as it funds its operations and capital expenditures. Until Rexahn has the capacity to generate revenues, Rexahn is relying upon outside funding resources to fund its cash flow requirements. If these resources are depleted or unavailable, it may be more difficult to develop its pipeline, Rexahn may be unable to continue to expand its operations or otherwise capitalize on its business opportunities, and Rexahn’s business, financial condition and results of operations would be materially adversely affected.

If the merger is not completed and Rexahn is unable to raise sufficient additional funds for the development and commercialization of its product candidates, whether through potential collaborative, partnering or other strategic arrangements or otherwise, or if Rexahn otherwise determines to discontinue the development of its product candidates, Rexahn will likely determine to cease operations. Even if Rexahn is able to raise additional funds to permit the continued development of its product candidates, if Rexahn and/or any potential collaborators are unable to develop and commercialize product candidates, if development is further delayed or is eliminated, or if sales revenue from any Rexahn product upon receiving marketing approval, if ever, is insufficient, Rexahn may never become profitable and it will not be successful.

As of August 10, 2020, Rexahn had only four full-time employees. Rexahn’s ability to successfully complete the merger depends in large part on its ability to retain certain remaining personnel. Despite Rexahn’s efforts to retain these employees, one or more may terminate their employment with Rexahn on short notice. The loss of the services of certain employees could potentially harm Rexahn’s ability to consummate the merger, to run its day-to-day business operations, as well as to fulfill its reporting obligations as a public company.

The pendency of the merger could disrupt Rexahn’s business in many ways, including:

Should they occur, any of these matters could adversely affect the trading price of Rexahn common stock or harm its business, financial condition and prospects.

Rexahn is a clinical-stage company with a limited number of product candidates. Rexahn currently does not have any products that have gained regulatory approval, and has not demonstrated an ability to perform the functions necessary for the successful commercialization of any of its product candidates. The successful commercialization of Rexahn’s product candidates will require it to first perform a variety of functions, including:

To date, Rexahn’s operations have been limited to organizing and staffing the Company, acquiring, developing and securing its proprietary technology, and undertaking product candidate research and development, including preclinical studies and clinical trials of its principal product candidates. These operations provide a limited basis for assessing Rexahn’s ability to commercialize product candidates.

The continued listing of Rexahn common stock on Nasdaq is contingent on Rexahn’s continued compliance with a number of listing standards. There is no assurance that Rexahn will remain in compliance with these standards. Delisting from Nasdaq would adversely affect Rexahn’s ability to consummate the merger, raise additional financing through the public or private sale of equity securities, significantly affect the ability of investors to trade Rexahn’s securities and negatively affect the value and liquidity of Rexahn common stock. Delisting also could limit Rexahn’s strategic alternatives and attractiveness to potential counterparties and have other negative results, including the potential loss of employee confidence, the loss of institutional investors or interest in business development opportunities. Moreover, Rexahn committed in connection with the sale of securities to use commercially reasonable efforts to maintain the listing of its common stock during such time that certain warrants are outstanding.

Rexahn’s existing and potential future product candidates require extensive clinical testing. Such testing is expensive and time-consuming and requires specialized knowledge and expertise. Human clinical trials are expensive and difficult to design and implement, in part because they are subject to rigorous regulatory requirements. The clinical trial process is also time-consuming, and the outcome is not certain. Rexahn estimates that clinical trials of its current and potential future product candidates will take multiple years to complete. Failure can occur at any stage of a clinical trial, and Rexahn could encounter problems that cause it to abandon or repeat clinical trials. The commencement and completion of clinical trials may be delayed or precluded by a number of factors, including: