SEC Form POS AM filed by Akari Therapeutics plc

As filed with the Securities and Exchange Commission on April 10, 2026

Registration No. 333-292930

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Post-Effective Amendment No. 1 to

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

AKARI THERAPEUTICS, PLC

(Exact name of registrant as specified in its charter)

401 East Jackson St, Suite 3300

Tampa, FL 33602

(929) 274-7510

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

Abizer Gaslightwala

President and Chief Executive Officer

401 East Jackson St, Suite 3300

Tampa, FL 33602

(929) 274-7510

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

Copies to:

Gary Emmanuel, Esq.

Win Rutherfurd, Esq.

Greenberg Traurig, LLP

One Vanderbilt Avenue

New York, NY 10017

Tel: (212) 801-9200

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

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, 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 post-effective amendment filed pursuant to Rule 462(d) 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.  ☐

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.  ☐

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, as amended, or until this registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

On January 23, 2026, the Registrant filed a registration statement on Form S-1 (File No. 333-292930) with the Securities and Exchange Commission (the “Registration Statement”).

This Post-Effective Amendment No. 1 to Form S-1 (the “Post-Effective Amendment”) is being filed to (i) update the contents of the prospectus contained in the Registration Statement pursuant to Section 10(a)(3) of the Securities Act of 1933, as amended, in respect of the continuous offering pursuant to Rule 415 of the securities registered hereby, (ii) incorporate by reference the Registrant’s reports filed by the Registrant pursuant to the Securities and Exchange Act of 1934, as amended, and (iii) as disclosed herein, this Post-Effective Amendment reflects the Ratio Change (as defined herein), which results in adjustments to the number of ADSs (as defined herein) presented throughout the Registration Statement.

No additional securities are being registered pursuant to this Post-Effective Amendment. All applicable registration fees were paid at the time of the original filing of the Registration Statement.

The information in this preliminary prospectus is not complete and may be changed. The selling stockholders may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Akari Therapeutics, PLC

867,023 American Depositary Shares Representing 69,361,812,000 Ordinary Shares

This prospectus relates to the offer and sale, by the selling stockholders identified in this prospectus, or the selling stockholders, from time to time of up to 867,023 American Depositary Shares, or ADSs, each representing 80,000 ordinary shares, $0.000000005 nominal value per share, or the Ordinary Shares, consisting of: (i) 315,187 ADSs representing 25,214,974,000 Ordinary Shares issuable upon the exercise of unregistered Series G Warrants issued in a concurrent private placement conducted together with a registered direct offering in December 2025, or the Registered Direct Offering, (ii) 64,092 ADSs representing 5,127,426,000 Ordinary Shares issuable upon exercise of unregistered pre-funded warrants, or the Pre-Funded Warrants, issued in a concurrent private placement, or the Private Placement and together with the Registered Direct Offering, the December 2025 Offerings, (iii) 237,568 ADSs representing 19,005,406,000 Ordinary Shares issuable upon exercise of Pre-Funded Warrants issued in a privately negotiated note cancellation and exchange, or the Exchange, (iv) 237,568 ADSs representing 19,005,406,000 Ordinary Shares issuable upon exercise of unregistered note exchange warrants, or the Note Exchange Warrants, issued in the Exchange, and (v) 12,608 ADSs representing 1,008,600,000 Ordinary Shares issuable upon exercise of placement agent warrants issued in connection with the Offerings, or the Placement Agent Warrants, and collectively with the foregoing Series G Warrants, Pre-Funded Warrants and Note Exchange Warrants, the Warrants.

We are not selling any ADSs being offered by this prospectus and will not receive any of the proceeds from the sale of such shares by the selling stockholders. All net proceeds from the sale of the ADSs covered by this prospectus will go to the Selling Stockholders. However, we may receive the proceeds from any exercise of Warrants if the holders do not exercise the Warrants on a cashless basis. See “Use of Proceeds.”

The selling stockholders may sell or otherwise dispose of the ADSs representing Ordinary Shares described in this prospectus in different ways and at varying prices. See “Plan of Distribution” for more information about how the selling stockholders may sell or otherwise dispose of ADSs representing Ordinary Shares being registered pursuant to the registration statement of which this prospectus forms a part.

We will pay the expenses of registering the offer and sale of the ADSs representing Ordinary Shares under the Securities Act of 1933, as amended, or the Securities Act, to which this prospectus relates by the selling stockholders, including legal and accounting fees. See “Plan of Distribution.”

Our ADSs are listed on the Nasdaq Capital Market under the symbol “AKTX.” On April 9, 2026, the closing price of our ADSs was $3.92.

INVESTING IN OUR SECURITIES INVOLVES SIGNIFICANT RISKS THAT ARE DESCRIBED IN THE “RISK FACTORS” SECTION BEGINNING ON PAGE 5 OF THIS PROSPECTUS

Neither the Securities and Exchange Commission, or the SEC, nor any state securities commission has approved or disapproved of the securities to be issued under this prospectus or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is         , 2026.

TABLE OF CONTENTS

About This Prospectus

This prospectus is part of a registration statement that we filed with the SEC under the Securities Act. Under this prospectus, the selling stockholders may, from time to time, sell the ADSs representing Ordinary Shares described in this prospectus in one or more transactions, as described herein. This prospectus provides you with a general description of the securities offered by the selling stockholders. We may also file a prospectus supplement to the registration statement of which this prospectus forms a part that may contain material information relating to this offering. Any prospectus supplement may also add, update or change information contained in this prospectus. Any statement that we make in this prospectus will be modified or superseded by any inconsistent statement made by us in a prospectus supplement or in any document incorporated by reference in this prospectus.

This prospectus is part of a registration statement that we filed with the SEC. As permitted by the rules and regulations of the SEC, the registration statement includes additional information not contained in this prospectus. You may read the registration statement and the other reports we file with the SEC at the SEC’s website or its offices described below under the heading “Where You Can Find More Information.”

You should rely only on the information contained in or incorporated by reference in this prospectus, any prospectus supplement and the registration statement. Neither we nor the selling stockholders have authorized anyone to provide you with different or additional information. If anyone provides you with different or inconsistent information, you should not rely on it. Offers to sell, and solicitations of offers to buy, our ADSs representing Ordinary Shares are being made only in jurisdictions where offers and sales are permitted. You should assume that the information contained in this prospectus, any prospectus supplement and the documents incorporated by reference herein is accurate only as of the respective dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

For investors outside of the United States: Neither we nor the selling stockholders have done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside of the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of our securities and the distribution of this prospectus outside of the United States.

The registration statement includes exhibits that provide more detail of the matters discussed in this prospectus. 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 summaries are qualified in their entirety by the actual documents. Copies of certain documents referred to herein have been filed, will be filed or are incorporated by reference as exhibits to the registration statement. You should read this prospectus, the documents incorporated by reference herein, the related exhibits filed with the SEC and any prospectus supplement, together with additional information described under the headings “Where You Can Find More Information” and “Incorporation by Reference,” before making your investment decision.

Unless the context otherwise requires, all references in this prospectus to the “Company,” “Akari,” “we,” “our,” “ours,” and “us” refer to Akari Therapeutics, Plc.

PROSPECTUS SUMMARY

Company Overview

We are an oncology company developing next-generation antibody-drug conjugates, or ADCs, designed around novel proprietary cancer-killing toxins, or payloads. We believe these novel payloads may have the potential to transform the efficacy and safety outcomes of ADCs as cancer therapies beyond options that are currently available or in development.

ADCs are a class of cancer therapies that combine the precision targeting of antibodies with payload toxins that attack cancer cells. To date, innovation in the field of ADC therapies has focused primarily on the development of novel antibodies linked to existing classes of payload toxins. For example, there is a range of approved ADCs with antibodies that target the Her2, Trop2, CD19, CD22, CD30, Nectin-4, Tissue Factor, and Folate Receptor alpha antibodies. But there is a surprising lack of diversity in the payload toxins to which those antibodies are linked, as all of these marketed products, and more than 90% of ADCs in late-stage clinical development of which we are aware, utilize payloads from just two standard classes: (1) microtubule inhibitors or (2) DNA-damaging agents such as topoisomerase I inhibitors.

Our differentiated ADC discovery and development platform, or our ADC Platform, enables us to generate a range of ADC product candidates that pair our novel payloads with biologically validated antibody targets prevalent in cancer tumors. Our lead payload, PH1, has demonstrated multiple modes of action in preclinical studies, including direct cytotoxicity and activation of the immune system through neoantigen formation. We believe that our focus on the development of ADCs that utilize our novel payloads may allow us to develop ADCs with benefits that include:

Our lead product candidate is AKTX-101, a preclinical stage Trop2-targeting ADC that combines PH1 with a proprietary antibody and linker construct designed to deliver the payload directly to tumor cells with minimal off-target effects. Trop-2 is expressed in a broad range of solid tumors, including lung, breast, bladder, gastric and pancreatic cancers. We are advancing AKTX-101 through IND-enabling studies with the goal of initiating a first-in-human Phase 1 clinical trial by late 2026 or early 2027. In addition, we have expanded our PH1-based pipeline with AKTX-102, a CEACAM5-directed ADC program that combines a novel CEACAM5-targeting antibody construct with PH1, reflecting the scope of our research capabilities, and the potential of our PH1 payload to be designed into novel ADC candidates. and ADC design capabilities while we prioritize resources on the lead program.

Our activities since inception have consisted of performing research and development activities and raising capital.

We do not have any products available for commercial sale, and we have not generated any product revenue from our portfolio of product candidates or other sources. Our ability to generate revenue sufficient to achieve profitability, if ever, will depend on the successful development and eventual commercialization of our potential therapies, which we expect, if it ever occurs, will take a number of years. The research and development efforts require significant amounts of additional capital and adequate personnel infrastructure. There can be no assurance that our research and development activities will be successfully completed, or that our potential therapies will be commercially viable.

Recent Developments

Ratio Change

On March 31, 2026, we effected a change in the ratio of our ADSs to our Ordinary Shares, or the Ratio Change, adjusting the ratio from one (1) ADS representing two thousand (2,000) Ordinary Shares to one (1) ADS representing eighty thousand (80,000) Ordinary Shares. The Ratio Change resulted in a one-for-forty (1-for-40) reverse split of our issued and outstanding ADSs and had no effect on our Ordinary Shares.

Corporate Information

We were originally established as a private limited company under the laws of England and Wales on October 7, 2004, under the name Freshname No. 333 Limited. On January 19, 2005, we changed our name to Morria Biopharmaceuticals Limited and on February 3, 2005, we completed a reverse merger with Morria Biopharmaceuticals Inc., or Morria, a Delaware corporation, in which Morria became our wholly owned subsidiary and we re-registered as a non-traded public limited company under the laws of England and Wales. On March 22, 2011, we incorporated an Israeli subsidiary, Morria Biopharma Ltd. On June 25, 2013, we changed our name to Celsus Therapeutics Plc and on October 13, 2013, Morria was renamed Celsus Therapeutics Inc. On September 18, 2015, we completed an acquisition of all of the capital stock of Volution Immuno Pharmaceuticals SA, or Volution, a private Swiss company, from RPC Pharma Limited, or RPC, Volution’s sole shareholder, in exchange for our Ordinary Shares, in accordance with the terms of a Share Exchange Agreement, dated as of July 10, 2015. In connection with the acquisition, our name was changed to Akari Therapeutics, Plc. As such, our affairs are governed by our Articles of Association and the English law.

Our principal office is located at 401 East Jackson Street, Suite 3300, Tampa, FL 33602, and our telephone number is (929) 274-7510. Our website address is www.akaritx.com. The information contained on, or accessible through, our website is not incorporated by reference into this prospectus, and you should not consider any information contained in, or that can be accessed through, our website as part of this prospectus or in deciding whether to purchase our securities.

The Offering

The number of Ordinary Shares outstanding is based on 1,131,656 ADSs (representing 90,532,530,000 Ordinary Shares) and 4,349,533 Ordinary Shares that are not represented by ADSs, totaling 90,536,879,533 Ordinary Shares outstanding as of December 31, 2025, after giving effect to the Ratio Change, and excludes:

Except as otherwise indicated, the information in this prospectus assumes or gives effect to:

RISK FACTORS

An investment in our securities involves a high degree of risk. You should consider carefully the risks below and the risk and uncertainties described under the heading “Risk Factors” in Item 1A of Part I of our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, which is incorporated by reference in this prospectus, including our audited consolidated financial statements and the related notes, as updated by our subsequent quarterly reports on Form 10-Q and other reports and documents that are incorporated by reference into this prospectus, before you decide whether to purchase our securities. If any of such risks actually occur, our business, financial condition, results of operations, cash flow and prospects could be materially and adversely affected. As a result, the trading price of our ADSs could decline and you could lose all or part of your investment in our ADSs.

Risks Related to this Offering

A substantial number of ADSs may be sold in this offering, which could cause the price of our ADSs to decline.

We are registering for resale 867,023 ADSs representing 69,361,812,000 Ordinary Shares issuable upon the exercise of Warrants held by the Selling Stockholders. This sale and any future sales of a substantial number of ADSs in the public market, or the perception that such sales may occur, could adversely affect the price of the ADSs on the Nasdaq Capital Market. We cannot predict the effect, if any, that market sales of those ADSs or the availability of those ADSs for sale will have on the market price of the ADSs.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements. Certain statements in this prospectus may constitute “forward-looking statements” for purposes of the federal securities laws. Our forward-looking statements include, but are not limited to, statements regarding expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Forward-looking statements in this prospectus may include, for example, statements about:

The forward-looking statements contained in this prospectus are based on current expectations and beliefs concerning future developments and their potential effects on the Company. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties, some of which are beyond our control, or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described in the section entitled “Risk Factors” and in our periodic filings with the SEC. Our SEC filings are available publicly on the SEC website at www.sec.gov. Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. Accordingly, forward-looking statements in this prospectus should not be relied upon as representing our views as of any subsequent date, and we undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws.

USE OF PROCEEDS

We will not receive any proceeds from the sale of the Ordinary Shares represented by ADSs by the selling stockholders. All net proceeds from the sale of the Ordinary Shares represented by ADSs covered by this prospectus will go to the selling stockholders. We expect that the selling stockholders will sell their Ordinary Shares represented by ADSs as described under “Plan of Distribution.”

We may receive proceeds from the exercise of the Warrants to the extent that these warrants are exercised for cash by the selling stockholders. The Warrants, however, are exercisable on a cashless basis (which could only occur if following the date that is six months following the original issuance date of the warrant, at the time of exercise hereof, there is no effective registration statement registering with a current prospectus available for the resale of the Ordinary Shares represented by ADSs underlying the warrants held by the selling stockholders). If all of the Warrants mentioned above were exercised for cash in full, the proceeds would be approximately $8.9 million. We intend to use the net proceeds of such Warrant exercise, if any, for working capital and general corporate purposes.

DIVIDENDS AND DIVIDEND POLICY

Since our inception, we have not declared or paid any dividends on our Ordinary Shares. We intend to retain any earnings for use in our business and do not currently intend to pay dividends on our Ordinary Shares. The declaration and payment of any future dividends will be at the discretion of our board of directors and will depend upon our results of operations, cash requirements, financial condition, contractual restrictions, restrictions imposed by our indebtedness, any future debt agreements or applicable laws and other factors that our board of directors may deem relevant.

See “Description of American Depositary Shares—Dividends and Other Distributions” in this prospectus for more information.

SELLING STOCKHOLDERS

The Ordinary Shares represented by ADSs being offered by the selling stockholders are those Ordinary Shares represented by ADSs issuable upon exercise of the Warrants issued in connection with the Offering and the Exchange. We are registering the Ordinary Shares represented by ADSs in order to permit the selling stockholders to offer the Ordinary Shares represented by ADSs for resale from time to time. Other than with respect to (i) Abizer Gaslightwala, who currently serves as our President and Chief Executive Officer and as a director; (ii) Hoyoung Huh, M.D., Ph.D., who currently serves as chairman of our board of directors; (iii) Kameel Farag who currently serves as the Interim Chief Financial Officer; and (iv) Dr. Samir R. Patel, Dr. Ray Prudo, Robert Bazemore, James Neal, and Sandip Patel who each currently serve as a director on our board of directors, the selling stockholders have not had any material relationship with us within the past three years.

The table below lists the selling stockholders and other information regarding the beneficial ownership of the Ordinary Shares represented by ADSs by each of the selling stockholders. The second column lists the number of Ordinary Shares represented by ADSs beneficially owned by each selling stockholder, based on its ownership of Ordinary Shares represented by ADSs and warrants to purchase Ordinary Shares represented by ADSs, as of January 22, 2026, assuming the exercise of the warrants held by the selling stockholders on that date, without regard to any other limitations on conversions or exercises. The third column lists the maximum number of Ordinary Shares represented by ADSs being offered in this prospectus by the selling stockholders, without regard to any limitations on conversions or exercises. The fourth and fifth columns list the amount and percentage of Ordinary Shares represented by ADSs owned after the Offering and the Exchange, assuming all of the Ordinary Shares represented by ADSs to be registered by the registration statement of which this prospectus is a part are sold in this offering, without regard to any limitations on conversions or exercises, and assuming that the selling stockholders do not acquire additional Ordinary Shares represented by ADSs after the date of this prospectus and prior to completion of this offering. The percentages of Ordinary Shares represented by ADSs owned after the Offering are based on 91,567,009,533 Ordinary Shares outstanding as of January 22, 2026. The information in the table below with respect to the selling stockholders has been obtained from the selling stockholders.

Under the terms of the Warrants, a selling stockholder may not exercise such Warrants to the extent such exercise would cause such selling stockholders, together with its affiliates, to beneficially own a number of shares of common stock which would exceed 4.99% or 9.99% (depending on the individual shareholder) of our then outstanding share capital following such exercise. The number of Ordinary Shares represented by ADSs in the third column does not reflect these limitations.

Information about the selling stockholders may change over time. Any changed information will be set forth in an amendment to the registration statement or supplement to this prospectus, to the extent required by law.

Description of SECURITIES

General

Our securities include (a) our Ordinary Shares, par value $0.000000005 per share, and (b) our ADSs, each representing 80,000 Ordinary Shares. Our Ordinary Shares are registered under the Exchange Act not for trading, but only in connection with the listing of the ADSs on the Nasdaq Capital Market.

Our ADSs are listed on the Nasdaq Capital Market under the trading symbol “AKTX.”

ADSs and Ordinary Shares

For a description of the ADSs and the Ordinary Shares underlying the ADSs, and of the provisions of our articles of association, please see Exhibit 3.1 to our Annual Report on Form 10-K for the year ended December 31, 2025, filed on March 30, 2026, which is incorporated by reference herein.

Stock Exchange Listing

Our ADSs have been listed on the Nasdaq Capital Market under the symbol “AKTX” since September 21, 2015.

ADS Depositary

Deutsche Bank Trust Company Americas, as our depositary, registers and delivers the ADSs. Each ADS represents ownership of 80,000 Ordinary Shares deposited with Deutsche Bank AG, London Branch with its principal office at Winchester House, 1 Great Winchester Street, London EC2N 2DB, U.K., as custodian for the depositary. Each ADS also represents ownership of any other securities, cash or other property, which may be held by the depositary. The depositary’s corporate trust office at which the ADSs are administered is located at 1 Columbus Circle, New York, NY 10019, USA. The principal executive office of the depositary is located at 1 Columbus Circle, New York, NY 10019, USA.

Description of American Depositary Shares

Stock Exchange Listing

Our ADSs have been listed on the Nasdaq Capital Market under the symbol “AKTX” since September 21, 2015.

American Depositary Shares

Deutsche Bank Trust Company Americas, as our depositary, registers and delivers the ADSs. Each ADS represents ownership of 80,000 Ordinary Shares deposited with Deutsche Bank AG, London Branch with its principal office at Winchester House, 1 Great Winchester Street, London EC2N 2DB, U.K., as custodian for the depositary. Each ADS also represents ownership of any other securities, cash or other property, which may be held by the depositary. The depositary’s corporate trust office at which the ADSs are administered is located at 1 Columbus Circle, New York, NY 10019, USA. The principal executive office of the depositary is located at 1 Columbus Circle, New York, NY 10019, USA.

The Direct Registration System (“DRS”), is a system administered by DTC, pursuant to which the depositary may register the ownership of uncertificated ADSs, which ownership shall be evidenced by periodic statements issued by the depositary to the ADS holders entitled thereto.

We do not treat ADS holders as shareholders and accordingly, ADS holders, do not have shareholder rights. English law governs shareholder rights. The depositary or its custodian is the holder of the Ordinary Shares underlying the ADSs. A holder of ADSs only has ADS holder rights. A deposit agreement among us, the depositary and the ADS holder, and the beneficial owners of ADSs sets out ADS holder rights as well as the rights and obligations of the depositary. The laws of the State of New York govern the deposit agreement and the ADSs.

The following is a summary of the material provisions of the deposit agreement.

Holding the ADSs

Each holder of ADSs may hold their ADSs either (1) directly (a) by having an American Depositary Receipt, or ADR, which is a certificate evidencing a specific number of ADSs, registered in the name of the holder, or (b) by holding ADSs in the DRS, or (2) indirectly through each holder’s broker or other financial institution. If one holds ADSs directly, then they are an ADS holder. The description set forth herein assumes that each holder holds their ADSs directly. If a holder holds the ADSs indirectly, they must rely on the procedures of their broker or other financial institution to assert the rights of ADS holders described in this section. Each holder of ADSs should consult with their broker or financial institution to find out what those procedures are.

Dividends and Other Distributions

The depositary has agreed to pay to ADS holders the cash dividends or other distributions it or the custodian receives on Ordinary Shares or other deposited securities, after deducting its fees and expenses. The holder of ADSs receives these distributions in proportion to the number of Ordinary Shares their ADSs represent as of the record date (which will be as close as practicable to the record date for our Ordinary Shares) set by the depositary with respect to the ADSs.

The depositary is not responsible if it decides that it is unlawful or impractical to make a distribution available to any ADS holders. We have no obligation to register ADSs, shares, rights or other securities under the Securities Act. We also have no obligation to take any other action to permit the distribution of ADSs, shares, rights or anything else to ADS holders. This means that ADS holders may not receive the distributions we make on our Ordinary Shares or any value for them if it is illegal or impractical for us to make them available to ADS holders.

Deposit, Withdrawal and Cancellation

The depositary will deliver ADSs if an ADS holder or its broker deposits Ordinary Shares or evidence of rights to receive Ordinary Shares with the custodian. Upon payment of its fees and expenses and of any taxes or charges, such as stamp taxes or stock transfer taxes or fees, the depositary will register the appropriate number of ADSs in the names the ADS holder requests and will deliver the ADSs to or upon the order of the person or persons entitled thereto.

You may turn in your ADSs at the depositary’s corporate trust office or by providing appropriate instructions to your broker. Upon payment of its fees and expenses and of any taxes or charges, such as stamp taxes or stock transfer taxes or fees, the depositary will deliver the Ordinary Shares and any other deposited securities underlying the ADSs to you or a person you designate at the office of the custodian. Or, at your request, risk and expense, the depositary will deliver the deposited securities at its corporate trust office, if feasible.

The depositary may refuse to accept for surrender ADSs only in the case of (i) temporary delays caused by closing our transfer books or those of the depositary or the deposit of our Ordinary Shares in connection with voting at a shareholders’ meeting or the payment of dividends, (ii) the payment of fees, taxes and similar charges and (iii) compliance with any laws or governmental regulations relating to depositary receipts or to the withdrawal of deposited securities. Subject thereto, in the case of surrender of a number of ADSs representing other than a whole number of our Ordinary Shares, the depositary will cause ownership of the appropriate whole number of our Ordinary Shares to be delivered in accordance with the terms of the deposit agreement and will, at the discretion of the depositary, either (i) issue and deliver to the person surrendering such ADSs a new ADS representing any remaining fractional ordinary share or (ii) sell or cause to be sold the fractional Ordinary Shares represented by the ADSs surrendered and remit the proceeds of such sale (net of applicable fees and charges of, and expenses incurred by, the depositary and taxes and/or governmental charges) to the person surrendering the ADS.

You may surrender your ADR to the depositary for the purpose of exchanging your ADR for uncertificated ADSs. The depositary will cancel that ADR and will send you a statement confirming that you are the owner of uncertificated ADSs. Alternatively, upon receipt by the depositary of a proper instruction from a holder of uncertificated ADSs requesting the exchange of uncertificated ADSs for certificated ADSs, the depositary will execute and deliver to you an ADR evidencing those ADSs.

Voting Rights

As an ADS holder, you may instruct the depositary how to vote the deposited shares your ADSs represent. Otherwise, you could exercise your right to vote directly if you withdraw the Ordinary Shares your ADSs represent. However, you may not know about the meeting enough in advance to withdraw the Ordinary Shares.

If we ask for your instructions and upon timely notice from us as described in the deposit agreement, the depositary will notify you of the upcoming vote and arrange to deliver our voting materials to you. The materials will (1) describe the matters to be voted on and (2) explain how you may instruct the depositary to vote the Ordinary Shares or other deposited securities underlying your ADSs as you direct.

We cannot assure you that you will receive the voting materials in time to ensure that you can instruct the depositary to vote the Ordinary Shares underlying your ADSs. In addition, the depositary and its agents are not responsible for failing to carry out your voting instructions or for the manner of carrying out your voting instructions. This means that you may not be able to exercise your right to vote and you may have no recourse if the Ordinary Shares underlying your ADSs are not voted as you requested.

In order to give you a reasonable opportunity to instruct the depositary as to the exercise of voting rights relating to deposited securities, if we request the depositary to act, we are required to give the depositary 30 days’ advance notice of any such meeting and details concerning the matters to be voted upon sufficiently in advance of the meeting date, and the depositary will mail you a notice.

Fees and Expenses

As a holder of ADSs, you will be required to pay the following fees to the depositary under the terms of the deposit agreement:

Payment of Taxes

As an ADS holder, you will be responsible for any taxes or other governmental charges payable on your ADSs or on the deposited securities represented by any of your ADSs. The depositary may refuse to register any transfer of your ADSs or allow you to withdraw the deposited securities represented by your ADSs until such taxes or other charges are paid. It may apply payments owed to you or sell deposited securities represented by your ADSs to pay any taxes owed and you will remain liable for any deficiency. If the depositary sells deposited securities, it will, if appropriate, reduce the number of ADSs to reflect the sale and pay to you any net proceeds, or send to you any property, remaining after it has paid the taxes. You agree to indemnify us, the depositary, the custodian and each of our and their respective agents, directors, employees and affiliates for, and hold each of them harmless from, any claims with respect to taxes (including applicable interest and penalties thereon) arising from any tax benefit obtained for you.

Amendment and Termination

We may agree with the depositary to amend the deposit agreement and the ADRs without your consent for any reason. If an amendment adds or increases fees or charges, except for taxes and other governmental charges or expenses of the depositary for registration fees, facsimile costs, delivery charges or similar items, or prejudices a substantial right of ADS holders, it will not become effective for outstanding ADSs until thirty (30) days after the depositary notifies ADS holders of the amendment. At the time an amendment becomes effective, you are considered, by virtue of continuing to hold your ADSs, to have agreed to the amendment and to be bound by the ADRs and the deposit agreement as amended.

The depositary will terminate the deposit agreement if we ask it to do so, in which case the depositary will give notice to you at least 90 days prior to termination. The depositary may also terminate the deposit agreement if the depositary has told us that it would like to resign and we have not appointed a new depositary within 90 days. In such case, the depositary must notify you at least 30 days before termination.

After termination, the depositary and its agents will do the following under the deposit agreement but nothing else: collect distributions on the deposited securities, sell rights and other property and deliver Ordinary Shares and other deposited securities upon cancellation of ADSs after payment of any fees, charges, taxes or other governmental charges. Six months or more after termination, the depositary may sell any remaining deposited securities by public or private sale. After that, the depositary will hold the money it received on the sale, as well as any other cash it is holding under the deposit agreement, for the pro rata benefit of the ADS holders that have not surrendered their ADSs. It will not invest the money and has no liability for interest. The depositary’s only obligations will be to account for the money and other cash. After termination, our only obligations will be to indemnify the depositary and to pay fees and expenses of the depositary that we agreed to pay.

Limitations on Obligations and Liability

Limits on our Obligations and the Obligations of the Depositary; Limits on Liability to Holders of ADSs

The deposit agreement expressly limits our obligations and the obligations of the depositary. It also limits our liability and the liability of the depositary. We and the depositary:

The depositary and any of its agents also disclaim any liability for any failure to carry out any instructions to vote, the manner in which any vote is cast or the effect of any vote or failure to determine that any distribution or action may be lawful or reasonably practicable or for allowing any rights to lapse in accordance with the provisions of the deposit agreement, the failure or timeliness of any notice from us, the content of any information submitted to it by us for distribution to you, as an ADS holder, or for any inaccuracy of any translation thereof, any investment risk associated with the acquisition of an interest in the deposited securities, the validity or worth of the deposited securities, the credit-worthiness of any third party, or for any tax consequences that may result from ownership of ADSs, Ordinary Shares or deposited securities.

In the deposit agreement, we and the depositary agree to indemnify each other under certain circumstances.

Requirements for Depositary Actions

Before the depositary will issue, deliver or register a transfer of an ADS, make a distribution on an ADS, or permit withdrawal of Ordinary Shares, the depositary may require:

The depositary may refuse to issue and deliver ADSs or register transfers of ADSs generally when the register of the depositary or our transfer books are closed or at any time if the depositary or we think it is necessary or advisable to do so.

Your Right to Receive the Shares Underlying Your ADSs

You have the right to cancel your ADSs and withdraw the underlying shares at any time except:

This right of withdrawal may not be limited by any other provision of the deposit agreement.

Direct Registration System

In the deposit agreement, all parties to the deposit agreement acknowledge that the DRS and Profile Modification System (“Profile”) will apply to uncertificated ADSs upon acceptance thereof to DRS by DTC. DRS is the system administered by DTC pursuant to which the depositary may register the ownership of uncertificated ADSs, which ownership shall be evidenced by periodic statements issued by the depositary to the ADS holders entitled thereto. Profile is a required feature of DRS which allows a DTC participant, claiming to act on behalf of an ADS holder, to direct the depositary to register a transfer of those ADSs to DTC or its nominee and to deliver those ADSs to the DTC account of that DTC participant without receipt by the depositary of prior authorization from the ADS holder to register such transfer.

In connection with and in accordance with the arrangements and procedures relating to DRS/Profile, the parties to the deposit agreement understand that the depositary will not verify, determine or otherwise ascertain that the DTC participant which is claiming to be acting on behalf of an ADS holder in requesting registration of transfer and delivery described in the paragraph above has the actual authority to act on behalf of the ADS holder (notwithstanding any requirements under the Uniform Commercial Code). In the deposit agreement, the parties agree that the depositary’s reliance on, and compliance with, instructions received by the depositary through the DRS/Profile system and in accordance with the deposit agreement, shall not constitute negligence or bad faith on the part of the depositary.

Pre-release of ADSs

The deposit agreement permits the depositary to deliver ADSs before deposit of the underlying Ordinary Shares. This is called a pre-release of the ADSs. The depositary may also deliver Ordinary Shares upon cancellation of pre-released ADSs (even if the ADSs are cancelled before the pre-release transaction has been closed out). A pre-release is closed out as soon as the underlying Ordinary Shares are delivered to the depositary. The depositary may receive ADSs instead of Ordinary Shares to close out a pre-release. The depositary may pre-release ADSs only under the following conditions: (1) before or at the time of the pre-release, the person to whom the pre-release is being made represents to the depositary in writing that it or its customer (a) owns the Ordinary Shares or ADSs to be deposited, (b) assigns all beneficial rights, title and interest in such Ordinary Shares or ADSs to the depositary for the benefit of the owners, (c) will not take any action with respect to such Ordinary Shares or ADSs that is inconsistent with the transfer of beneficial ownership, (d) indicates the depositary as owner of such Ordinary Shares or ADSs in its records, and (e) unconditionally guarantees to deliver such Ordinary Shares or ADSs to the depositary or the custodian, as the case may be; (2) the pre-release is fully collateralized with cash or other collateral that the depositary considers appropriate; and (3) the depositary must be able to close out the pre-release on not more than five business days’ notice. Each pre-release is subject to further indemnities and credit regulations as the depositary considers appropriate. In addition, the depositary will normally limit the number of ADSs that may be outstanding at any time as a result of pre-release to 30% of the aggregate number of ADSs then outstanding, although the depositary, in its sole discretion, may disregard the limit from time to time, if it thinks it is appropriate to do so, including (1) due to a decrease in the aggregate number of ADSs outstanding that causes existing pre-release transactions to temporarily exceed the limit stated above or (2) where otherwise required by market conditions. The depositary may also set limits with respect to the number of ADSs and shares involved in pre-release transactions with any one person on a case-by-case basis as it deems appropriate.

PLAN OF DISTRIBUTION

The selling stockholders of the securities and any of their pledgees, assignees and successors-in-interest may, from time to time, sell any or all of their securities covered hereby on the principal market or any other stock exchange, market or trading facility on which the securities are traded or in private transactions. These sales may be at fixed or negotiated prices. The selling stockholders may use any one or more of the following methods when selling securities:

If the selling stockholders effect such transactions by selling Ordinary Shares represented by ADSs to or through underwriters, broker-dealers or agents, such underwriters, broker-dealers or agents may receive commissions in the form of discounts, concessions or commissions from the selling stockholders or commissions from purchasers of the Ordinary Shares represented by ADSs for whom they may act as agent or to whom they may sell as principal (which discounts, concessions or commissions as to particular underwriters, broker-dealers or agents may be in excess of those customary in the types of transactions involved). In connection with sales of Ordinary Shares represented by ADSs or otherwise, the selling stockholders may enter into hedging transactions with broker-dealers, which may in turn engage in short sales of the Ordinary Shares represented by ADSs in the course of hedging in positions they assume. The selling stockholders may also sell Ordinary Shares represented by ADSs short and deliver Ordinary Shares represented by ADSs covered by this prospectus to close out short positions and to return borrowed shares in connection with such short sales. The selling stockholders may also loan or pledge Ordinary Shares represented by ADSs to broker-dealers that in turn may sell such shares.

The selling stockholders may pledge or grant a security interest in some or all of the ADSs or Warrants owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the Ordinary Shares represented by ADSs from time to time pursuant to this prospectus or any amendment to this prospectus under Rule 424(b) or other applicable provision of the Securities Act of 1933, as amended, amending, if necessary, the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer and donate the Ordinary Shares represented by ADSs in other circumstances in which case the transferees, donees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

The selling stockholders and any broker-dealer participating in the distribution of the Ordinary Shares represented by ADSs may be deemed to be “underwriters” within the meaning of the Securities Act, and any commission paid, or any discounts or concessions allowed to, any such broker-dealer may be deemed to be underwriting commissions or discounts under the Securities Act. At the time a particular offering of the Ordinary Shares represented by ADSs is made, a prospectus supplement, if required, will be distributed which will set forth the aggregate amount of Ordinary Shares represented by ADSs being offered and the terms of the offering, including the name or names of any broker-dealers or agents, any discounts, commissions and other terms constituting compensation from the selling stockholders and any discounts, commissions or concessions allowed or reallowed or paid to broker-dealers.

Under the securities laws of some states Ordinary Shares represented by ADSs may be sold in such states only through registered or licensed brokers or dealers. In addition, in some states Ordinary Shares represented by ADSs may not be sold unless such Ordinary Shares have been registered or qualified for sale in such state or an exemption from registration or qualification is available and is complied with.

There can be no assurance that any selling stockholders will sell any or all of the Ordinary Shares represented by ADSs registered pursuant to the registration statement, of which this prospectus forms a part.

The selling stockholders and any other person participating in such distribution will be subject to applicable provisions of the Exchange Act, and the rules and regulations thereunder, including, without limitation, Regulation M of the Exchange Act, which may limit the timing of purchases and sales of any of the Ordinary Shares represented by ADSs by the selling stockholders and any other participating person. Regulation M may also restrict the ability of any person engaged in the distribution of the Ordinary Shares represented by ADSs to engage in market-making activities with respect to the Ordinary Shares represented by ADSs. All of the foregoing may affect the marketability of the Ordinary Shares represented by ADSs and the ability of any person or entity to engage in market-making activities with respect to the Ordinary Shares represented by ADSs.

We will pay all expenses of the registration of the Ordinary Shares represented by ADSs, estimated to be $65,336.26 in total, including, without limitation, Securities and Exchange Commission filing fees and expenses of compliance with state securities or “blue sky” laws; provided, however, that a selling stockholder will pay all underwriting discounts and selling commissions, if any.

Our ADSs are currently listed on The Nasdaq Capital Market under the symbol “AKTX”.

LEGAL MATTERS

The validity of the securities offered by this prospectus has been passed upon for us by Greenberg Traurig, LLP, London, England.

EXPERTS

The consolidated financial statements of Akari Therapeutics, Plc as of December 31, 2025 and 2024 and for the years then ended incorporated by reference in this Prospectus and Registration Statement have been so incorporated in reliance on the report of BDO USA, P.C., an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting. The report on the consolidated financial statements contains an explanatory paragraph regarding the Company’s ability to continue as a going concern.

INCORPORATION BY REFERENCE

The SEC allows us to “incorporate by reference” information into this prospectus, which means that we can disclose important information to you by referring to those documents. We hereby “incorporate by reference” the documents listed below, which means that we are disclosing important information to you by referring you to those documents. The Registration Statement, including the exhibits, can be read at the SEC website referred to below under “Where You Can Find More Information.” The information that we file later with the SEC will automatically update and in some cases supersede this information. Specifically, we incorporate by reference the following documents or information filed with the SEC (other than, in each case, documents or information deemed to have been furnished and not filed in accordance with SEC rules):

In addition, all documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (not including any information furnished under Item 2.02, 7.01 or 9.01 of Form 8-K or any other information that is identified as “furnished” rather than filed, which information is not incorporated by reference herein), prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this registration statement and to be a part hereof from the date of filing of such documents.

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

We will furnish without charge to you, on written or oral request, a copy of any or all of the documents incorporated by reference in this prospectus, including exhibits to these documents. You should direct any requests for documents to Akari Therapeutics, Plc, 401 East Jackson Street, Suite 3300, Tampa, FL 33602, Attention: Abizer Gaslightwala.

ENFORCEMENT OF FOREIGN JUDGMENTS

We are incorporated under the laws of England and Wales. Several of our directors and officers reside outside the United States, and a portion of our assets and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may be difficult for you to serve legal process on us or certain of our directors and executive officers or have any of them appear in a U.S. court.

It may be difficult for U.S. investors to bring and/or effectively enforce suits against our company in England. Although English courts do recognize U.S. judgments unless there is an overriding jurisdictional or public policy reason not to do so, if a judgment is obtained in the U.S. courts based on the civil liability provisions of U.S. federal securities laws against us, difficulties may arise in enforcing the judgment against us in the English courts. The enforceability of any U.S. judgment in the United Kingdom will depend on the particular facts of the case as well as the laws and treaties in effect at the time. The United States and the United Kingdom do not currently have a treaty providing for reciprocal recognition and enforcement of judgments (other than arbitration awards) in civil and commercial matters. It may similarly be difficult for U.S. investors to bring an original action in the English courts to enforce liabilities based on U.S. federal securities laws.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC and does not contain all the information set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus to any of our contracts, agreements, or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference into this prospectus for a copy of such contract, agreement, or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly, and current reports, proxy statements, and other information with the SEC. The SEC maintains an Internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. Our SEC filings are available to the public over the Internet on the SEC’s website at http://www.sec.gov.

Our website address is www.akaritx.com. The information contained on, or accessible through, our website is not incorporated into this prospectus and does not form a part hereof (other than those filings with the SEC that we specifically incorporate by reference into the prospectus or any supplement to this prospectus).

Akari Therapeutics, PLC

867,023 American Depositary Shares Representing 69,361,812,000 Ordinary Shares

PROSPECTUS

, 2026

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

The following table sets forth the estimated expenses to be borne by the registrant in connection with the issuance and distribution of the securities being registered hereby.

The Registrant’s articles of association provide that, subject to the Companies Act, every director or other officer (excluding an auditor) of the Registrant may be indemnified out of the assets of the Registrant against all costs, charges, expenses, losses or liabilities incurred by him in performing his duties or the exercise of his powers or otherwise in relation to or in connection with his duties, powers or office.

The Registrant also maintains directors and officers insurance to insure such persons against certain liabilities.

The expenses listed above do not include expenses of preparing prospectus supplements and other expenses relating to offerings of particular securities.

Within the past three years, we sold the securities described below, which were not registered under the Securities Act, pursuant to the exemption provided by Section 4(a)(2) of the Securities Act or Rule 506 of Regulation D promulgated thereunder.

September 2023 Private Placement

On October 6, 2023, we closed a private placement (the “September 2023 Private Placement”) with certain investors, including Dr. Ray Prudo, our director and former Chairman, and Ms. Rachelle Jacques, our former President and CEO, issuing an aggregate of 551,816 American Depositary Shares (“ADSs”), each representing 2,000 ordinary shares, at $3.30 per ADS, and pre-funded warrants to purchase up to 48,387 ADSs at a purchase price per Pre-Funded Warrant of $3.10, for aggregate gross proceeds of approximately $2.0 million. The pre-funded warrants are exercisable at an exercise price of $0.20 per ADS and will not expire until exercised in full. In connection with this offering, we agreed to issue to Paulson Investment Company, LLC (“Paulson”), as placement agent for the September 2023 Private Placement, warrants to purchase 42,550 ADSs at an exercise price of $4.13 per ADS (representing 125% of the price per ADS in the September 2023 Private Placement) and a term expiring on September 22, 2028. Net proceeds, after deducting placement agent fees and other expenses, were approximately $1.7 million.

December 2023 Private Placement

In December 2023, we closed a private placement with certain investors, including Dr. Ray Prudo, our former Chairman, and Dr. Samir Patel, our director, issuing an aggregate of 947,868 ADSs at $2.11 per ADS, for aggregate gross proceeds of approximately $2.0 million. Net proceeds, after deducting placement agent fees and other expenses, were approximately $1.8 million.

November 2024 Private Placement

In November 2024, we closed a private placement (the “November 2024 Private Placement”) with certain investors, including Dr. Ray Prudo and Dr. Samir Patel, issuing an aggregate of 1,713,402 ADSs, and Series D Warrants (the “Series D Warrants”) to purchase up to 1,713,402 ADSs, at a per unit price of $2.26 for aggregate gross proceeds of $3.2 million. The Series D Warrants are exercisable immediately, have terms ranging from December 2, 2027 to June 2, 2028, and include cashless exercise provisions in limited circumstances.

We incurred a total of $204,000 in placement agent fees with Paulson, and in April 2025, issued 408,000,000 ordinary shares to Paulson in lieu of $204,000 in cash payment. Net proceeds, after deducting placement agent fees and other expenses, were approximately $2.8 million.

March 2025 Private Placement

On March 2, 2025, we entered into a securities purchase agreement (the “March 2025 Purchase Agreement”) for a private placement (the “March 2025 Offering”), pursuant to which we issued an aggregate of (i) 4,942,626 ADSs, (ii) 1,650,000 pre-funded warrants (iii) 8,340,436 Series A Warrants and (iv) 6,637,626 Series B Warrants. The initial closing took place on March 6, 2025, and the final closing took place on April 25, 2025.

The net proceeds from the March 2025 Offering, after deducting placement agent fees and other offering expenses payable by us, were approximately $5.6 million.

August 2025 Note Offering

On August 7, 2025, we entered into Note Purchase Agreements with certain investors, including the Company’s directors (the “Note Investors”), in a private placement offering (the “Note Offering”). Pursuant to these agreements, the Note Investors agreed to purchase, and we agreed to issue unsecured promissory notes with a 20% original issuance discount (each a “Note” and together, the “Notes”). In connection with the Note Offering, we agreed to extend the expiration date of Series A Warrants by 48 months from their original date of expiration through Warrant Amendment Agreements.

On August 15, 2025 and August 18, 2025 (the “Closing Dates”), we completed the first tranche of closings for the Note Offering, issuing Notes with an aggregate purchase price of $2,261,000 and an aggregate principal amount of $2,826,250, which includes a note exchange with the Company’s Chairman, Dr. Hoyoung Huh, as outlined below. The Notes mature 12 months from their respective Closing Dates, at which time the principal amount becomes due and payable. On the Closing Dates, we also entered into the Warrant Amendment Agreements with certain Note Investors, extending the expiration date of Series A Warrants to purchase an aggregate of 1,973,211 ADSs.

As part of the first tranche, Dr. Hoyoung Huh, the Company’s Chairman, purchased a Note with a principal amount of $1,250,000 for a purchase price of $1,000,000. The purchase price was satisfied through a cash payment of $162,567 and the cancellation of $837,433 in outstanding principal and accrued interest under a senior secured promissory note previously issued to him by our wholly owned subsidiary, Peak Bio Inc., in January 2024 (the “Peak Bio Note”). On August 7, 2025, we entered into a Loan Cancellation and Exchange Agreement, whereby the Peak Bio Note was cancelled and extinguished to partially satisfy the purchase price of the Note purchased by Dr. Huh.

We agreed to pay a 5% advisory fee in cash on the total gross cash proceeds of approximately $1.4 million to the placement agent in connection with the Notes issued and sold on the Closing Dates.

In December 2025, approximately $4 million principal amount of the Notes were exchanged for (i) pre-funded warrants to purchase up to an aggregate of 9,502,703 ADSs and (ii) note exchange warrants to purchase up to an aggregate of 9,502,703 ADSs.

October 2025 Offering

On October 14, 2025, we entered into the March 2025 Purchase Agreement, pursuant to which we sold an aggregate of (i) 3,125,000 ADSs, (ii) 3,125,000 Series E Warrants to purchase up to 3,125,000 ADS and (iii) 3,125,000 Series F Warrants to purchase up to 3,125,000 ADS. The initial closing took place on October 16, 2025. In connection with the October 2025 Offering, we agreed to issue to Ladenburg Thalmann & Co. Inc., as the placement agent for the October 2025 Offering, warrants to purchase up to 125,000 ADSs at an exercise price of $1.00 per ADS and a term expiring on October 14, 2030.

The aggregate gross proceeds from the October 2025 Offering were approximately $2.5 million, excluding any proceeds from any future exercises of the Series E Warrants and Series F Warrants.

December 2025 Offering

On December 16, 2025, we entered into a securities purchase agreement with certain institutional investors providing for the issuance and sale, in a registered direct offering (the “Registered Direct Offering”), of 10,043,774 ADSs. The ADSs have been offered and sold together with Series G Warrants to purchase up to an aggregate of 10,043,774 ADSs, which were issued in a concurrent private placement. The combined purchase price per ADS and accompanying Series G Warrant sold in the Registered Direct Offering is $0.3883.

In a concurrent private placement, pursuant to a securities purchase agreement dated as of December 16, 2025, the Company agreed to issue to certain directors and officers of the Company (i) unregistered Pre-Funded Warrants to purchase an aggregate of 2,563,713 ADSs at an exercise price per ADS of $0.00001, and (ii) accompanying Series G Warrants to purchase an aggregate of 2,563,713 ADSs, at a combined purchase price of $0.4041 per Pre-Funded Warrant and Series G Warrant.

The aggregate gross proceeds from the December 2025 Offering were approximately $5 million, excluding any proceeds from any future exercises of the Series G Warrants.

The securities described above were offered and sold pursuant to the exemption from the registration provided by Section 4(a)(2) of the Securities Act or Rule 506 of Regulation D promulgated thereunder.

The exhibits to the registration statement are listed in the Exhibit Index attached hereto and incorporated by reference herein.

No financial statement schedules are provided because the information called for is not required or is shown either in financial statements or the related notes.

Exhibit Index

* Filed herewith.

+ Previously filed.

The undersigned registrant hereby undertakes:

provided, however, that paragraphs (1)(i), (ii) and (iii) above do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-1 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, State of Massachusetts on this 10 day of April, 2026.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons on behalf of the registrant and in the capacities and on the dates indicated.