424B3

424B3 1 d112040d424b3.htm 424B3 424B3

Filed Pursuant to Rule 424(b)(3)
Registration No. 333-298910

PROSPECTUS

Up to 3,500,000 American Depositary Shares

LOGO

Representing 3,500,000 Ordinary Shares

This prospectus relates to the resale from time to time by the selling securityholder identified in this prospectus of up to 3,500,000 American Depositary Shares, or ADSs, each representing one ordinary share, with a nominal value of $0.000042 per share, or the ordinary shares, of Autolus Therapeutics plc, issuable upon the exercise of a warrant, or the Warrant, issued to Perceptive Credit Holdings V, LP, or Perceptive, on July 30, 2026, with an exercise price of $1.9314 per ADS. The Warrant has an expiration date of July 30, 2036.

We are filing the registration statement of which this prospectus forms a part to fulfill our contractual obligations under the Registration Rights Agreement, dated as of July 30, 2026, or the Registration Rights Agreement, between us and Perceptive, to provide for the registration with the Securities and Exchange Commission, or the SEC, of the resale by the selling securityholder of the ADSs issuable upon exercise of the Warrant. See “Selling Securityholder” beginning on page 15 of this prospectus for more information about the selling securityholder. The registration of the ADSs to which this prospectus relates does not require the selling securityholder to sell any of its ADSs.

The selling securityholder may, from time to time, sell, transfer or otherwise dispose of any or all of the ADSs being registered or interests in the ADSs being registered on any stock exchange, market or trading facility on which our ADSs or ordinary shares are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices. Prices may vary from purchaser to purchaser during the period of distribution. See “Plan of Distribution.” We are not offering any ADSs or ordinary shares under this prospectus and will not receive any of the proceeds from the sale or other disposition of the ADSs or ordinary shares by the selling securityholder. Upon the exercise of the Warrant for cash, we will receive the exercise price of the Warrant. The net proceeds received from the sale or other disposition of our securities by the selling securityholder, if any, is unknown.

We may amend or supplement this prospectus from time to time by filing amendments or supplements as required. You should read the entire prospectus, including the additional information described under the heading “Incorporation of Documents by Reference,” and any amendments or supplements carefully before you make your investment decision. The ADSs are listed on the Nasdaq Global Select Market, or Nasdaq, under the symbol “AUTL.” On September 8, 2026, the closing sale price of the ADSs on Nasdaq was $2.11.

Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks that we have described under the caption “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, which is incorporated by reference into this prospectus. We may also include specific risk factors in supplements to this prospectus under the caption “Risk Factors.”

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

The date of this prospectus is September 22, 2026.

TABLE OF CONTENTS


	Page

ABOUT THIS PROSPECTUS		1

PROSPECTUS SUMMARY		2

RISK FACTORS		6

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS		7

USE OF PROCEEDS		10

PLAN OF DISTRIBUTION		11

DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION		14

SELLING SECURITYHOLDER		15

TAXATION		17

LEGAL MATTERS		26

EXPERTS		26

SERVICE OF PROCESS AND ENFORCEMENT OF LIABILITIES		27

WHERE YOU CAN FIND MORE INFORMATION		29

INCORPORATION OF DOCUMENTS BY REFERENCE		30

ABOUT THIS PROSPECTUS

Neither we nor the selling securityholder have authorized anyone to provide you with additional information or information different from that contained in this prospectus filed with the Securities and Exchange Commission, or SEC in any supplement to this prospectus filed with the SEC, in any free writing prospectus filed with the SEC, or in the documents described under the heading “Incorporation of Documents by Reference.” We and the selling securityholder take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. The selling securityholder is offering to sell, and seeking offers to buy, our ADSs only in jurisdictions where offers and sales are permitted. The information contained in this prospectus is accurate only as of the date of this prospectus, regardless of the time of delivery of this prospectus or any sale of our ADSs. Our business, financial condition, results of operations and prospects may have changed since that date.

For investors outside the United States: Neither we nor the selling securityholder 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 the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the ADSs and the distribution of this prospectus outside the United States.

This prospectus may be supplemented from time to time by one or more prospectus supplements. Such prospectus supplements may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement, you must rely on the information in the prospectus supplement. You should carefully read both this prospectus and any applicable prospectus supplement before deciding to invest in any ADSs being offered.

To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any document incorporated by reference filed with the SEC before the date of this prospectus, on the other hand, you should rely on the information in this prospectus. If any statement in a document incorporated by reference is inconsistent with a statement in another document incorporated by reference having a later date, the statement in the document having the later date modifies or supersedes the earlier statement.

Unless otherwise indicated in this prospectus, “Autolus,” “the company,” “our company,” “we,” “us” and “our” refer to Autolus Therapeutics plc and its subsidiaries.

PROSPECTUS SUMMARY

The following summary highlights selected information contained elsewhere in this prospectus and does not contain all of the information that you need to consider in making your investment decision. We urge you to read this entire prospectus, including the more detailed consolidated financial statements, notes to the consolidated financial statements and other information incorporated by reference from our other filings with the SEC or included in any applicable prospectus supplement. Investing in our securities involves risks. Therefore, carefully consider the risk factors set forth in any prospectus supplements and in our most recent filings with the SEC including our Annual Report on Form 10-K for the year ended December 31, 2025, which is incorporated by reference herein, as well as other information in this prospectus and any prospectus supplements and the documents incorporated by reference herein or therein, before purchasing our securities. Each of the risk factors could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities.

Company Overview

We are a commercial-stage biopharmaceutical company developing, manufacturing and delivering next-generation T cell therapies and candidates for the treatment of cancer and autoimmune diseases. Using our broad suite of proprietary and modular T cell programming technologies, we are engineering precisely targeted and controlled T cell therapies that are designed to better recognize target cells, break down their defense mechanisms and eliminate target cells. We believe our programmed T cell therapies have the potential to be best-in-class and offer patients substantial benefits over the existing standard of care, including the potential for cure in some patients. In November 2024, the United States Food and Drug Administration, or the FDA, approved our biologics license application, or BLA, for the marketing of AUCATZYL (obecabtagene autoleucel, also known as obe-cel) in the United States for the treatment of adult patients (18 years and older) with relapsed or refractory B-cell precursor acute lymphoblastic leukemia, or r/r B-ALL. The commercial launch and first sale of AUCATZYL in the United States occurred in January 2025. The United Kingdom Medicines and Healthcare products Regulatory Agency granted AUCATZYL conditional marketing authorization in April 2025. In November 2025, the National Institute for Health and Care Excellence recommended AUCATZYL for use in the National Health Service, or NHS, in England and Wales as a treatment option for adult patients (age 26 and older) with r/r B-ALL. We launched AUCATZYL in the United Kingdom in January 2026 and it is available through routine commissioning by the NHS. In July 2025, the European Commission granted marketing authorization for AUCATZYL in adult patients (age 26 and older) with r/r B-ALL. Evaluation of potential pricing and feasibility of market entry opportunities in certain European Union, or EU, countries is ongoing; however, at this time, launch in the EU is on hold and we do not anticipate any EU sales of AUCATZYL in 2026.

AUCATZYL is a B-lymphocyte antigen CD19 chimeric antigen receptor T cell therapy. AUCATZYL is designed with a fast target binding off-rate to minimize excessive activation of the programmed T cells. Adult r/r B- ALL is an extremely aggressive type of blood cancer with a high unmet medical need in the treatment of patients once they relapse, where historically patients suffer from poor outcomes. AUCATZYL is manufactured at our dedicated commercial manufacturing site, the Nucleus, in Stevenage, U.K. We intend for the Nucleus to meet the global supply demands of AUCATZYL, with Cardinal Health serving as our commercial distribution partner in the US.

In addition to AUCATZYL/obe-cel for the treatment of adult r/r B-ALL, we are advancing obe-cel in other oncology indications including pediatric B-ALL and B-NHL. Data from the Phase 1b cohort of the ongoing Phase 1b/2 CATULUS trial evaluating the safety and efficacy of obe-cel in pediatric B-ALL and B-NHL patients was presented at the American Society of Hematology, or ASH Annual Meeting in December 2025. Data show the safety profile of obe-cel in pediatric patients is consistent with that previously reported in adults, with low rates of high-grade cytokine release syndrome, or CRS, and immune effector cell-associated neurotoxicity syndrome, or ICANS. Overall response rate was high at 95%, and nearly 90% of responders had ongoing

remission at data cut-off. Enrollment into the Phase 2 cohort is ongoing, and in October 2025, the FDA granted regenerative medicine advanced therapy designation to obe-cel for the treatment of pediatric patients with r/r B-ALL. Obe-cel is also being developed for the treatment of autoimmune indications, and we have initiated a Phase 1 trial in patients with severe, refractory systemic lupus erythematosus. Data from the ongoing Phase 1 CARLYSLE trial evaluating obe-cel in patients with severe refractory systemic lupus erythematosus was presented at the ASH Annual Meeting in December 2025. The data showed deep, durable responses in patients receiving the 50 million obe-cel dose level, and initial data suggest substantial early improvement in three patients dosed with obe-cel at 100 million dose level. All patients show deep B-cell depletion after infusion, suggesting an immune reset. Nine patients were evaluable for safety, and no ICANS or high-grade CRS were observed.

We are enrolling patients in our Phase 2 clinical trial of obe-cel in severe, refractory lupus nephritis and we expect to report data in 2028. We are also advancing obe-cel in a Phase 1 dose escalation clinical trial in progressive multiple sclerosis and expect to present first preliminary results, including safety, PK/PD and biomarker data, in the first quarter of 2027.

Our T cell programming technologies allow us to tailor our therapies to address the specific disease we are targeting and introduce new programming modules into a patient’s T cells to give those T cells improved properties to better recognize target cells and overcome fundamental disease defense mechanisms. Cancers in particular thrive on their ability to fend off T cells by evading recognition by T cells and by establishing other defense mechanisms, such as checkpoint inhibition, and creating a hostile microenvironment. We believe our leadership in T cell programming technologies will provide us with a competitive advantage as we look to develop future generations of T cell therapies targeting hematological cancers, solid tumors and autoimmune diseases, including potential products that could have a sufficient tolerability profile to enable use in outpatient settings.

Corporate Information

We are a public limited company, originally incorporated pursuant to the laws of England and Wales in February 2018 as a private company with limited liability called Autolus Therapeutics Limited. Autolus Limited was originally incorporated under the laws of England and Wales in July 2014. Pursuant to the terms of a corporate reorganization carried out in June 2018, the shareholders of Autolus Limited exchanged each of the shares held by them in Autolus Limited for the same number and class of newly issued shares of Autolus Therapeutics Limited and, as a result, Autolus Limited became a wholly owned subsidiary of Autolus Therapeutics Limited. On June 18, 2018, Autolus Therapeutics Limited re-registered as a public limited company and was renamed Autolus Therapeutics plc. On June 22, 2018, the different classes of our issued share capital were converted into a single class of ordinary shares and various classes of deferred shares, and we completed our IPO on the Nasdaq Global Select Market, or “Nasdaq”. Our ADSs trade on Nasdaq under the symbol “AUTL”. Our ordinary shares are not listed.

Our registered office and principal executive offices are located at the MediaWorks, 191 Wood Lane, White City, London W12 7FP, United Kingdom and our telephone number is +44 20 3829 6230. Our agent for service of process in the United States is Autolus Inc., 15810 Gaither Drive, Gaithersburg, Maryland, 20877. Our website address is www.autolus.com. The information contained on our website is not incorporated by reference into this prospectus, and you should not consider any information contained on, or that can be accessed through, our website as part of this prospectus or in deciding whether to purchase our securities.

Implications of Being a Foreign Private Issuer

Although we qualify as a foreign private issuer, we have decided to voluntarily file periodic reports, such as annual reports on Form 10-K (including our Annual Report on Form 10-K for the fiscal year ended December 31, 2025), quarterly reports on Form 10-Q and current reports on Form 8-K on U.S. domestic issuer forms, which are

more detailed and extensive in certain respects, and which must be filed more promptly, than the forms currently available to foreign private issuers. Similarly, we have decided to file registration statements, including the registration statement on Form S-3 of which this prospectus forms a part, on U.S. domestic issuer forms. Although we have voluntarily chosen to file registration statements, periodic reports and current reports on U.S. domestic issuer forms, we maintain our status as a foreign private issuer as long as we meet the qualifications for a foreign private issuer under the Exchange Act. Accordingly, as a foreign private issuer, we remain exempt from the U.S. federal proxy rules pursuant to Section 14 of the Exchange Act and Regulations 14A and 14C thereunder, Regulation FD, and our officers, directors, and principal shareholders are not subject to the short-swing profit recovery provisions contained in Section 16 of the Exchange Act.

THE OFFERING

ADSs offered by the selling securityholder

Up to 3,500,000 ADSs, each ADS representing one ordinary share, issuable upon exercise of the Warrant held by the selling securityholder.

Ordinary shares to be outstanding after this offering

269,662,540 (assuming the sale of all 3,500,000 ADSs, issuable upon exercise of the Warrant held by the selling securityholder), based on the number of ordinary shares outstanding as of August 10, 2026.

Use of proceeds

The selling securityholder will receive all of the net proceeds from this offering. We will not receive any proceeds from the sale of ADSs in this offering. We will, however, bear the costs incurred in connection with the registration of these ADSs. Upon the exercise of the Warrant for cash, we will receive the exercise price of the Warrant. The exercise price of the Warrant is $1.9314 per ADS.

American Depositary Shares

Each ADS represents one ordinary share, nominal value $0.000042 per share. ADSs may be evidenced by American Depositary Receipts, or ADRs. The depositary will hold the ordinary shares underlying the ADSs in a custody account with the custodian, and you will have the rights of an ADS holder or beneficial owner (as applicable) as provided in the deposit agreement among us, the depositary and holders and beneficial owners of ADSs. To better understand the terms of our ADSs, see the description under the caption “American Depositary Shares” in Exhibit 4.3 to our Annual Report on Form 10-K, filed with the SEC on March 27, 2026. We also encourage you to read the deposit agreement, which is filed as Exhibit 4.1 to the registration statement of which this prospectus forms a part.

Depositary

Citibank, N.A.

Custodian

Citibank, N.A. (London)

Nasdaq Global Select Market symbol

“AUTL”

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in any applicable prospectus supplement and any related free writing prospectus, and under similar headings in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as may be updated by our subsequent Quarterly Reports on Form 10-Q or in other subsequent filings with the SEC, which are incorporated by reference into this prospectus, before deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus is a part. Each of the risk factors could adversely affect our business, results of operations, financial condition and cash flows, as well as adversely affect the value of an investment in our securities, and the occurrence of any of these risks might cause you to lose all or part of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference into this prospectus contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act, that involve substantial risks and uncertainties. Any forward-looking statement involves known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to differ materially from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statement. In some cases, forward-looking statements are identified by the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “future,” “goals,” “intend,” “likely,” “may,” “might,” “ongoing,” “objective,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “strategy,” “target,” “will” and “would” or the negative of these terms, or other comparable terminology intended to identify statements about the future, although not all forward-looking statements contain these identifying words. These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these forward-looking statements.

The forward-looking statements contained in this prospectus and the documents incorporated by reference into this prospectus are based upon information available to us as of the date of this prospectus and, while we believe we have a reasonable basis for each forward-looking statement contained in this prospectus, we caution you that these statements are based on a combination of facts and factors currently known by us and our expectations of the future, about which we cannot be certain. Forward-looking statements include statements about:

•

the therapeutic potential and expected clinical benefits of AUCATZYL/obe-cel (obecabtagene autoleucel) for adult patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia, or r/r B-ALL;

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our ability to generate revenues from AUCATZYL, which is dependent upon maintaining significant market acceptance among physicians, patients and healthcare payors;

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our ability to maintain regulatory approval of AUCATZYL in the United States, or the US, to obtain and maintain regulatory approval for obe-cel for adult r/r B-ALL in additional territories and the timing thereof, and to obtain and maintain regulatory approval of our other product candidates in the indications for which we plan to develop them, and any related restrictions, limitations or warnings in the label of an approved drug or therapy;

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our expectations regarding the commercialization and marketing of AUCATZYL for adult r/r B-ALL, including expanding into additional territories and the related timing of reaching patients in such territories;

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the development of our commercial product and product candidates, including statements regarding the initiation, timing, progress and the results of clinical studies or trials and related preparatory work, the period during which the results of the trials will become available and our research and development programs;

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our estimates regarding expenses, future revenue, capital requirements and needs for additional financing;

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our commercialization, marketing and manufacturing capabilities and strategy for AUCATZYL, including our ability to successfully recruit and retain sales and marketing personnel and to successfully build the market for AUCATZYL;

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our expectations about the willingness of healthcare providers to recommend AUCATZYL to people with adult r/r B-ALL;

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the impacts of public health crises and their effects on our operations and business, including interruption of key clinical trial activities, such as clinical trial site monitoring, access to capital, and

potential disruption in the operations and business of third-party manufacturers, clinical sites, contract research organizations, or CROs, other service providers and collaborators with whom we conduct business;

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our expectations regarding our ability to obtain and maintain intellectual property protection and our ability to license additional intellectual property relating to our product candidates from third parties and to comply with our existing license agreements;

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our plans to research, develop, manufacture and commercialize our product candidates;

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the potential benefits of our commercial product and product candidates;

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the timing or likelihood of regulatory filings and approvals for our product candidates, along with regulatory developments in the US, European Union, or the EU, the United Kingdom, or the U.K., and other foreign countries;

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the size and growth potential of the markets for our commercial product and product candidates, if approved, and the rate and degree of market acceptance of our commercial product and product candidates, including reimbursement that may be received from payors;

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our need for and ability to obtain additional funding, on favorable terms or at all;

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our expectations regarding our strategic financing facility with Perceptive, including our ability to draw down additional tranches under the facility, our ability to achieve the revenue targets or other conditions applicable to future tranches, and our ability to satisfy our repayment and other obligations under the facility;

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the potential exercise by the investors of our dilutive instruments, including the exercise of the Warrant by the selling securityholder;

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our plans to collaborate, or statements regarding our current collaborations with BioNTech SE, or BioNTech, and others;

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our license and option agreement with BioNTech, including our potential to receive milestone payments and royalties under the agreement;

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our ability to attract collaborators with development, regulatory and commercialization expertise;

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our ability to identify, recruit and retain qualified employees and key personnel;

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our ability to contract with third-party suppliers and manufacturers and their ability to perform adequately;

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the scalability and commercial viability of our manufacturing methods and processes;

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the success of competing therapies that are or may become available;

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whether we are classified as a Passive Foreign Investment Company, or PFIC, for current and future periods;

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additional costs and expenses related to our decision to voluntarily comply with certain U.S. domestic issuer reporting obligations before we are required to do so;

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any other factors which may impact our financial results or future trading prices of our ADSs and the impact of securities analysts’ reports on these prices;

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any other factors discussed under the headings “Business,” “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our most recent Annual Report on Form 10-K, as well as any amendments or updates to our risk factors reflected in subsequent filings with the SEC, which are incorporated by reference into this prospectus, together with other information in this prospectus, the documents incorporated by reference, any prospectus supplement and any free writing prospectus that we may authorize.

You should refer to the “Risk Factors” section included in this prospectus and in the other documents incorporated herein for a discussion of important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law, applicable regulations or the rules of any stock exchange to which we are subject.

You should read this prospectus, any applicable prospectus supplement, any free writing prospectuses that we may authorize for use in connection with an offering and the documents that we reference in this prospectus and have filed as exhibits to the registration statement of which this prospectus is a part completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete. Our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.

USE OF PROCEEDS

We will not receive any of the proceeds from the sale of ADSs in this offering. The selling securityholder will receive all of the proceeds from the sale of ADSs hereunder. We will, however, bear the costs incurred in connection with the registration of these ADSs.

Upon the exercise of the Warrant for cash, we will receive the exercise price of the Warrant. The exercise price of the Warrant is $1.9314 per ADS. The Warrant may also be exercised on a cashless basis, in which case we would not receive any cash proceeds from such exercise.

PLAN OF DISTRIBUTION

The selling securityholder, which, as used herein, includes donees, pledgees, transferees, distributees, or other successors-in-interest selling our ADSs and our ordinary shares represented thereby or, collectively, the securities, or interests in securities received after the date of this prospectus from the selling securityholder as a gift, pledge, distribution, or other transfer, may, from time to time, sell, transfer, distribute, or otherwise dispose of certain of its securities on any stock exchange, market, or trading facility on which securities are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market prices, at varying prices determined at the time of sale, or at negotiated prices.

The selling securityholder may use any one or more of the following methods when disposing of its securities or interests therein:

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ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

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one or more underwritten offerings;

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block trades in which the broker-dealer will attempt to sell the securities as agent, but may position and resell a portion of the block as principal to facilitate the transaction;

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purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

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an exchange distribution in accordance with the rules of the applicable exchange;

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privately negotiated transactions;

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distributions to its members, partners, or shareholders;

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short sales effected, and the settlement of short sales entered into, after the date of the registration statement of which this prospectus forms a part is declared effective by the SEC;

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through the writing or settlement of options or other hedging transactions, whether through an options exchange or otherwise;

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in market transactions, including transactions on a national securities exchange or quotations service or over-the-counter market;

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directly to one or more purchasers;

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through agents;

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through broker-dealers who may agree with the selling securityholder to sell a specified number of such securities at a stipulated price per ADS or ordinary share; or

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a combination of any such methods of sale.

The selling securityholder may, from time to time, pledge or grant a security interest in some securities owned by it and, if the selling securityholder defaults in the performance of its secured obligations, the pledgees or secured parties may offer and sell such securities, from time to time, under this prospectus, or under an amendment or supplement to this prospectus amending the list of the selling securityholder to include the pledgee, transferee, or other successors-in-interest as the selling securityholder under this prospectus. The selling securityholder also may transfer securities in other circumstances, in which case the transferees, pledgees, or other successors-in-interest will be the selling beneficial owners for purposes of this prospectus.

In connection with the sale of securities or interests therein, the selling securityholder may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of such securities in the course of hedging the positions they assume. The selling securityholder may also sell securities short and deliver these securities to close out its short positions, or loan or pledge securities to broker-dealers that in

turn may sell these securities. The selling securityholder may also enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities that require the delivery to such broker-dealer or other financial institution of securities offered by this prospectus, which securities such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The aggregate proceeds to the selling securityholder from the sale of securities offered by it will be the purchase price of such securities, less discounts or commissions, if any. The selling securityholder reserves the right to accept and, together with its agents from time to time, to reject, in whole or in part, any proposed purchase of securities to be made directly or through agents. We will not receive any of the proceeds from any offering by the selling securityholder.

The selling securityholder also may in the future resell a portion of the securities in open-market transactions in reliance upon Rule 144 under the Securities Act (provided that it meets the criteria and conforms to the requirements of that rule), or pursuant to other available exemptions from the registration requirements of the Securities Act.

The selling securityholder and any underwriters, broker-dealers, or agents that participate in the sale of securities or interests therein may be “underwriters” within the meaning of Section 2(11) of the Securities Act. Any discounts, commissions, concessions, or profit it earns on any resale of such securities may be underwriting discounts and commissions under the Securities Act. If the selling securityholder is an “underwriter” within the meaning of Section 2(11) of the Securities Act, then the selling securityholder will be subject to the prospectus delivery requirements of the Securities Act. Underwriters and their controlling persons, dealers, and agents may be entitled, under agreements entered into with us and the selling securityholder, to indemnification against and contribution toward specific civil liabilities, including liabilities under the Securities Act.

To the extent required, the number of securities to be sold, the respective purchase prices and public offering prices, the names of any agent, dealer, or underwriter, and any applicable discounts, commissions, concessions, or other compensation with respect to a particular offer will be set forth in an accompanying prospectus supplement or, if appropriate, a post-effective amendment to the registration statement that includes this prospectus.

To facilitate the offering of securities offered by the selling securityholder, certain persons participating in the offering may engage in transactions that stabilize, maintain, or otherwise affect the price of the securities. This may include over-allotments or short sales, which involve the sale by persons participating in the offering of more securities than were sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment option, if any. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

Under the Registration Rights Agreement by and between the Company and Perceptive, dated as of July 30, 2026, or the Registration Rights Agreement, we have agreed to indemnify the selling securityholder against certain liabilities that it may incur in connection with the sale of the securities registered hereunder, including liabilities under the Securities Act, and to contribute to payments that the selling securityholder may be required to make with respect thereto. In addition, we and the selling securityholder may agree to indemnify any underwriter, broker-dealer, or agent against certain liabilities related to the selling of the securities, including liabilities arising under the Securities Act.

We have agreed to maintain the effectiveness of the registration statement of which this prospectus forms a part until all such securities have been sold under such registration statement or under Rule 144 under the Securities Act or are no longer outstanding, or under other circumstances as described in the Registration Rights Agreement. We have agreed to pay all expenses in connection with this offering, other than underwriting fees, discounts, selling commissions, stock transfer taxes, and certain legal expenses. The selling securityholder will pay, on a pro rata basis, any underwriting fees, discounts, selling commissions, stock transfer taxes, and certain legal expenses relating to the offering.

The selling securityholder may use this prospectus in connection with resales of securities. This prospectus and any accompanying prospectus supplement will identify the selling securityholder, the terms of the securities, and any material relationships between us and the selling securityholder. The selling securityholder may be deemed to be an underwriter under the Securities Act in connection with securities it resells and any profits on the sales may be deemed to be underwriting discounts and commissions under the Securities Act. Unless otherwise set forth in a prospectus supplement, the selling securityholder will receive all the net proceeds from the resale of securities.

The selling securityholder may elect to make an in-kind distribution of securities to its members, partners, or shareholders pursuant to the registration statement of which this prospectus forms a part by delivering a prospectus. To the extent that such members, partners, or shareholders are not affiliates of ours, such members, partners, or shareholders would thereby receive freely tradable securities pursuant to the distribution through a registration statement.

DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION

For information regarding our share capital and articles of association, please refer to the description of our securities filed as Exhibit 4.3 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, filed with the SEC on March 27, 2026, and the full text of our articles of association, filed as Exhibit 3.1 to the registration statement of which this prospectus forms a part, as well as any amendments thereto reflected in our subsequent filings with the SEC, all of which are incorporated by reference herein.

SELLING SECURITYHOLDER

The ADSs being offered by the selling securityholder are those issuable upon exercise of the Warrant issued to Perceptive in connection with the Note Purchase Agreement and Guaranty, dated as of July 30, 2026, or the Note Purchase Agreement, by and among the Company, certain subsidiaries of the Company, the noteholders party thereto and Perceptive, as administrative agent for the noteholders. Under the Note Purchase Agreement, the Company issued the Warrant to Perceptive on July 30, 2026 to purchase up to 3,500,000 ADSs at an exercise price of $1.9314 per ADS. The Warrant has an expiration date of July 30, 2036 and may be exercised on a cashless basis. The Company and Perceptive entered into the Registration Rights Agreement, dated as of July 30, 2026, pursuant to which the Company agreed to file a registration statement to register the resale of the ADSs issuable upon exercise of the Warrant. For additional information regarding the Note Purchase Agreement, the Warrant and our relationship with Perceptive, see the Current Report on Form 8-K filed with the SEC on August 3, 2026. We are registering the ADSs in order to permit the selling securityholder to offer ADSs for resale from time to time.

The table below sets forth, to our knowledge, information about the selling securityholder as of September 10, 2026.

We do not know when or in what amounts the selling securityholder may offer ADSs registered for resale pursuant to the registration statement of which this prospectus forms a part, and the selling securityholder might not sell any or all of such ADSs. Because the selling securityholder may offer all or some of such ADSs and because there are currently no agreements or understandings with respect to the sale of any ADSs, we cannot estimate the number of ADSs that will be held by the selling securityholder after completion of this offering. However, for purposes of this table, we have assumed that, after completion of this offering, none of such ADSs will be held by the selling securityholder.

Beneficial ownership is determined in accordance with the rules of the SEC and includes voting or investment power with respect to our ordinary shares (including in the form of ADSs), including ordinary shares beneficially owned pursuant to outstanding options, warrants and other derivative securities that are exercisable or exchangeable for our ordinary shares within 60 days of September 10, 2026. The inclusion of any shares in this table does not constitute an admission of beneficial ownership.

The selling securityholder may have sold or transferred some or all of its ordinary shares since the date on which the information in the table below is presented. Information about the selling securityholder may change over time.


Name of Selling Securityholder	Number of Shares Beneficially Owned Prior to the Offering⁽¹⁾		Percentage of Shares Beneficially Owned Prior to the Offering⁽¹⁾			Number of Shares Registered for Sale Hereby			Number of Shares Beneficially Owned After the Offering⁽¹⁾		Percentage of Shares Beneficially Owned After the Offering⁽¹⁾
Perceptive Credit Holdings V, LP(2)		3,500,000		1.3	%		3,500,000	⁽³⁾		—		—

(1)

This table is based upon information supplied by the selling securityholder, which information may not be accurate as of the date hereof. We have determined beneficial ownership in accordance with the rules of the SEC. Applicable percentages are based on 266,162,540 shares outstanding on August 10, 2026.

(2)

The ADSs to be registered for sale hereunder consist of up to 3,500,000 ADSs issuable upon the exercise of the Warrant issued to Perceptive on July 30, 2026. Perceptive Credit Holdings V, LP is a Delaware limited partnership. Perceptive Credit Opportunities GP, LLC is the general partner of Perceptive Credit Holdings V, LP. Joseph Edelman is the sole member of Perceptive Credit Opportunities GP, LLC. The address of the principal business office of Perceptive Credit Holdings V, LP is c/o Perceptive Advisors LLC, 51 Astor Place, 10th Floor, New York, NY 10003.

(3)

The number of shares registered for sale assumes no anti-dilution adjustments have been made to the number of ADSs issuable upon exercise of the Warrant. The actual number of ADSs issuable upon exercise of the Warrant may be higher or lower depending on any adjustments made pursuant to the terms of the Warrant.

TAXATION

The following summary contains a description of material U.K. and U.S. federal income tax consequences of the acquisition, ownership and disposition of our ADSs. This summary should not be considered a comprehensive description of all the tax considerations that may be relevant to beneficial owners of ADSs.

Material U.S. Federal Income Tax Considerations for U.S. Holders

The following is a description of the material U.S. federal income tax consequences to the U.S. Holders (as defined below) of owning and disposing of our ADSs. It is not a comprehensive description of all tax considerations that may be relevant to a particular person’s decision to acquire securities. This discussion applies only to a U.S. Holder that holds our ADSs as a capital asset for tax purposes within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended, or the Code, (generally, property held for investment). In addition, it does not describe all of the tax considerations that may be relevant in light of a U.S. Holder’s particular circumstances, including state, local and non-U.S. tax considerations, estate and gift tax considerations, the impact of special tax accounting rules under Section 451(b) of the Code or the alternative minimum tax provisions of the Code, the potential application of the Medicare contribution tax, and tax considerations applicable to U.S. Holders subject to special rules, such as

•

banks, insurance companies, and certain other financial institutions;

•

U.S. expatriates and certain former citizens or long-term residents of the United States;

•

dealers or traders in securities who use a mark-to-market method of tax accounting;

•

persons holding ADSs as part of a hedging transaction, “straddle,” wash sale, conversion transaction or integrated transaction or persons entering into a constructive sale with respect to ADSs;

•

persons whose “functional currency” for U.S. federal income tax purposes is not the U.S. dollar;

•

brokers, dealers or traders in securities, commodities or currencies;

•

tax-exempt entities or government organizations;

•

S corporations, partnerships, or other entities or arrangements classified as partnerships for U.S. federal income tax purposes (and investors therein);

•

regulated investment companies or real estate investment trusts;

•

tax qualified retirement plans;

•

persons who acquired ADSs pursuant to the exercise of any employee share option or otherwise as compensation;

•

persons that own or are deemed to own 10 percent or more of our shares including shares represented by ADSs (by vote or value); and

•

persons holding our ADSs in connection with a trade or business, permanent establishment, or fixed base outside the United States.

If an entity that is classified as a partnership for U.S. federal income tax purposes holds ADSs, the U.S. federal income tax treatment of a partner will generally depend on the status of the partner and the activities of the partnership.

Partnerships holding ADSs and partners in such partnerships are encouraged to consult their tax advisers as to the particular U.S. federal income tax consequences of holding and disposing of ADSs.

The discussion is based on the Code, administrative pronouncements, judicial decisions, final, temporary and proposed Treasury Regulations, and the income tax treaty between the United Kingdom and the United

States, or the Treaty, all as of the date hereof, changes to any of which may affect the tax consequences described herein, possibly with retroactive effect. There can be no assurances that the U.S. Internal Revenue Service, or the IRS, will not take a position different from what is described below concerning the tax consequences of the ownership and disposition of ADSs or that such a position would not be sustained by a court.

A “U.S. Holder” is a holder who, for U.S. federal income tax purposes, is a beneficial owner of ADSs who is eligible for the benefits of the Treaty and is:

(i) a citizen or individual resident of the United States;

(ii) a corporation, or other entity taxable as a corporation, created or organized in or under the laws of the United States, any state therein or the District of Columbia;

(iii) an estate the income of which is subject to U.S. federal income taxation regardless of its source; or

(iv) a trust if (1) a U.S. court is able to exercise primary supervision over the administration of the trust and one or more U.S. persons have authority to control all substantial decisions of the trust or (2) the trust has a valid election to be treated as a U.S. person under applicable U.S. Treasury Regulations.

U.S. Holders are encouraged to consult their tax advisers concerning the U.S. federal, state, local and non-U.S. tax consequences of owning and disposing of ADSs in their particular circumstances.

THESE PARAGRAPHS ARE A SUMMARY OF CERTAIN U.S. TAX CONSIDERATIONS AND ARE INTENDED AS A GENERAL GUIDE ONLY. IT IS RECOMMENDED THAT ALL HOLDERS OF ADSs OBTAIN ADVICE AS TO THE CONSEQUENCES OF THE ACQUISITION, OWNERSHIP AND DISPOSAL OF THE ADSs IN THEIR OWN SPECIFIC CIRCUMSTANCES FROM THEIR OWN TAX ADVISORS.

The discussion below assumes that the representations contained in the deposit agreement are true and that the obligations in the deposit agreement and any related agreement will be complied with in accordance with their terms. A U.S. Holder of ADSs will generally be treated for U.S. federal income tax purposes as the beneficial owner of the underlying ordinary shares that such ADSs represent. The remainder of this discussion assumes that a U.S. Holder of the ADSs will be treated in this manner. Accordingly, no gain or loss will be recognized if a U.S. Holder exchanges ADSs for the underlying shares represented by those ADSs.

Passive Foreign Investment Company Rules

If we are classified as a passive foreign investment company, or a PFIC in any taxable year, a U.S. Holder will be subject to special rules generally intended to reduce or eliminate any benefits from the deferral of U.S. federal income tax that a U.S. Holder could derive from investing in a non-U.S. company that does not distribute all of its earnings on a current basis.

We will be a PFIC for any taxable year in which (i) 75% or more of our gross income consists of passive income or (ii) 50% or more of the average quarterly value of our assets consists of assets that produce, or are held for the production of, passive income, including cash (other than certain cash held in non-interest bearing accounts for short-term working capital needs). For purposes of these tests, passive income includes dividends, interest, gains from the sale or exchange of investment property and certain rents and royalties. In addition, for purposes of the above calculations, a non-U.S. corporation that directly or indirectly owns at least 25% by value of the shares of another corporation is treated as if it held its proportionate share of the assets and directly received its proportionate share of the income of such other corporation.

Based on our analysis of our income, assets, activities and market capitalization, we believe we were not a PFIC for our taxable year ended December 31, 2025. However, the determination of whether we are a PFIC is a

fact-intensive determination made on an annual basis and the applicable law is subject to varying interpretation. In particular, the characterization of our assets as active or passive may depend in part on our current and intended future business plans, which are subject to change, and the value of marketable securities and other passive assets that we may hold from time to time may fluctuate considerably. In addition, for our current and future taxable years, the total value of our assets for PFIC testing purposes may be determined in part by reference to the market price of our ordinary shares or ADSs from time to time, which may fluctuate considerably. Under the income test, our status as a PFIC depends on the composition of our income which will depend on the transactions we enter into in the future and our corporate structure. The composition of our income and assets is also affected by how, and how quickly, we spend the cash we raise in any offering. Even if we determine that we are not a PFIC for a taxable year, there can be no assurance that the IRS will agree with our conclusion and that the IRS would not successfully challenge our position. Accordingly, our U.S. counsel expresses no opinion with respect to our PFIC status for our taxable year ended December 31, 2025, the current taxable year or any future taxable year.

If we are classified as a PFIC in any year with respect to which a U.S. Holder owns ADSs, we will continue to be treated as a PFIC with respect to such U.S. Holder in all succeeding years during which the U.S. Holder owns the ADSs, regardless of whether we continue to meet the tests described above unless (i) we cease to be a PFIC and the U.S. Holder has made a “deemed sale” election under the PFIC rules, (ii) we cease to be a PFIC and the U.S. Holder has a valid mark-to-market election in effect (as described below) or (iii) the U.S. Holder makes a Qualified Electing Fund Election, or QEF Election, with respect to all taxable years during such U.S. Holder’s holding period in which we are a PFIC.

If a U.S. Holder makes an effective QEF Election, the U.S. Holder will be required to include in gross income each year, whether or not we make distributions, as capital gains, such U.S. Holder’s pro rata share of our net capital gains and, as ordinary income, such U.S. Holder’s pro rata share of our earnings in excess of our net capital gains. However, a U.S. Holder can only make a QEF Election with respect to ADSs in a PFIC if such company agrees to furnish such U.S. Holder with certain tax information annually. However, there is no assurance that we will have timely knowledge of our status as a PFIC in the future or that the required information will be provided at a time that will permit a U.S. Holder to make or maintain a QEF Election. An electing U.S. Holder’s basis in ADSs will be increased to reflect the amount of any taxed but undistributed income. Distributions of income that had previously been taxed will result in a corresponding reduction of basis in the ADSs and may not be taxed again as distributions to the U.S. Holder. However, we do not currently expect to pay distributions with respect to our ADSs. U.S. Holders should consult with their tax advisors regarding the implications of owning stock in a PFIC, including whether and how to make and maintain a QEF Election.

If the “deemed sale” election is made, a U.S. Holder will be deemed to have sold the ADSs the U.S. Holder holds at their fair market value and any gain from such deemed sale would be subject to the rules described below. After the deemed sale election, so long as we do not become a PFIC in a subsequent taxable year, the U.S. Holder’s ADSs with respect to which such election was made will not be treated as shares in a PFIC and the U.S. Holder will not be subject to the rules described below with respect to any “excess distribution” the U.S. Holder receives from us or any gain from an actual sale or other disposition of the ADSs. U.S. Holders should consult their tax advisors as to the possibility and consequences of making a deemed sale election if we cease to be a PFIC and such election becomes available.

For each taxable year we are treated as a PFIC with respect to U.S. Holders, U.S. Holders will be subject to special tax rules with respect to any “excess distribution” such U.S. Holder receives and any gain such U.S. Holder recognizes from a sale or other disposition (including a pledge) of ADSs, unless (i) such U.S. Holder makes a QEF Election with respect to all taxable years of a U.S. Holder’s holding period during which we are a PFIC or makes a “deemed sale” purging election to cause a deemed sale of the ADSs at their fair market value in conjunction with a QEF Election or (ii) our ADSs constitute “marketable” securities, and such U.S. Holder makes a mark-to-market election as discussed below. Distributions a U.S. Holder receives in a taxable year that are greater than 125% of the average annual distributions a U.S. Holder received during the shorter of the three

preceding taxable years or the U.S. Holder’s holding period for the ADSs will be treated as an excess distribution. Under these special tax rules:

•

the excess distribution or gain will be allocated ratably over a U.S. Holder’s holding period for the ADSs;

•

the amount allocated to the current taxable year, and any taxable year prior to the first taxable year in which we became a PFIC, will be treated as ordinary income; and

•

the amount allocated to each other year will be subject to the highest tax rate in effect for that year and the interest charge generally applicable to underpayments of tax will be imposed on the resulting tax attributable to each such year.

The tax liability for amounts allocated to years prior to the year of disposition or the year of an “excess distribution” cannot be offset by any net operating losses for such years, and gains (but not losses) realized on the sale of the ADSs cannot be treated as capital, even if a U.S. Holder holds the ADSs as capital assets.

If we are a PFIC, a U.S. Holder will generally be subject to similar rules with respect to distributions we receive from, and our dispositions of the stock of, any of our direct or indirect subsidiaries that also are PFICs, as if such distributions were indirectly received by, and/or dispositions were indirectly carried out by, such U.S. Holder. U.S. Holders should consult their tax advisors regarding the application of the PFIC rules to our subsidiaries.

U.S. Holders can avoid the interest charge on excess distributions or gain relating to the ADSs by making a mark-to-market election with respect to the ADSs provided that the ADSs are “marketable.” ADSs will be marketable if they are “regularly traded” on certain U.S. stock exchanges or on a foreign stock exchange that meets certain conditions. For these purposes, the ADSs will be considered regularly traded during any calendar year during which they are traded, other than in de minimis quantities, on at least 15 days during each calendar quarter. Any trades that have as their principal purpose meeting this requirement will be disregarded. Our ADSs are listed on Nasdaq, which is a qualified exchange for these purposes. Consequently, if our ADSs remain listed on Nasdaq and are regularly traded, we expect the mark-to-market election would be available to U.S. Holders if we are a PFIC. Each U.S. Holder should consult its tax advisor as to whether a mark-to-market election is available or advisable with respect to the ADSs.

A U.S. Holder that makes a mark-to-market election must include as ordinary income for each year an amount equal to the excess, if any, of the fair market value of the ADSs at the close of the taxable year over the U.S. Holder’s adjusted tax basis in the ADSs. Accordingly, such mark-to-market election may accelerate the recognition of income without a corresponding receipt of cash. An electing holder may also claim an ordinary loss deduction for the excess, if any, of the U.S. Holder’s adjusted basis in the ADSs over the fair market value of the ADSs at the close of the taxable year, but this deduction is allowable only to the extent of any net mark-to-market gains for prior years. Gains from an actual sale or other disposition of the ADSs will be treated as ordinary income, and any losses incurred on a sale or other disposition of the ADSs will be treated as an ordinary loss to the extent of any net mark-to-market gains for prior years. Once made, the election cannot be revoked without the consent of the IRS unless the ADSs cease to be marketable.

However, a mark-to-market election generally cannot be made for equity interests in any lower-tier PFICs that we own, unless shares of such lower-tier PFIC are themselves “marketable.” As a result, even if a U.S. Holder validly makes a mark-to-market election with respect to our ADSs, the U.S. Holder may continue to be subject to the PFIC rules (described above) with respect to its indirect interest in any of our investments that are treated as an equity interest in a PFIC for U.S. federal income tax purposes. U.S. Holders should consult their tax advisors as to the availability and desirability of a mark-to-market election, as well as the impact of such election on interests in any lower-tier PFICs.

Unless otherwise provided by the U.S. Treasury, each U.S. shareholder of a PFIC is required to file an annual report containing such information as the U.S. Treasury may require. A U.S. Holder’s failure to file the

annual report will cause the statute of limitations for such U.S. Holder’s U.S. federal income tax return to remain open with regard to the items required to be included in such report until three years after the U.S. Holder files the annual report, and, unless such failure is due to reasonable cause and not willful neglect, the statute of limitations for the U.S. Holder’s entire U.S. federal income tax return will remain open during such period. U.S. Holders should consult their tax advisors regarding the requirements of filing such information returns under these rules.

Taxation of Distributions

Subject to the discussion above under “Passive Foreign Investment Company Rules,” distributions paid on ADSs, other than certain pro rata distributions of ADSs, will generally be treated as dividends to the extent paid out of our current or accumulated earnings and profits (as determined under U.S. federal income tax principles). Because we may not calculate our earnings and profits under U.S. federal income tax principles, we expect that distributions generally will be reported to U.S. Holders as dividends. Subject to applicable limitations, dividends paid to certain non-corporate U.S. Holders may be taxable at preferential rates applicable to “qualified dividend income.” However, the qualified dividend income treatment will not apply if we are treated as a PFIC for the taxable year in which a dividend is paid or the preceding year. The amount of the dividend will be treated as foreign-source dividend income to U.S. Holders and will not be eligible for the dividends-received deduction generally available to U.S. corporations under the Code. Dividends will generally be included in a U.S. Holder’s income on the date of the U.S. Holder’s receipt of the dividend. The amount of any dividend income paid in foreign currency will be the U.S. dollar amount calculated by reference to the exchange rate in effect on the date of actual or constructive receipt, regardless of whether the payment is in fact converted into U.S. dollars. If the dividend is converted into U.S. dollars on the date of receipt, a U.S. Holder should not be required to recognize foreign currency gain or loss in respect of the dividend income. A U.S. Holder may have foreign currency gain or loss if the dividend is converted into U.S. dollars after the date of receipt. Such gain or loss would generally be treated as U.S.-source ordinary income or loss. The amount of any distribution of property other than cash (and other than certain pro rata distributions of ADSs or rights to acquire ADSs) will be the fair market value of such property on the date of distribution.

For foreign tax credit limitation purposes, our dividends will generally be treated as passive category income. Because no U.K. income taxes will be withheld from dividends on ADSs, there will be no creditable foreign taxes associated with any dividends that a U.S. Holder will receive.

Sale or Other Taxable Disposition of ADSs

Subject to the discussion above under “Passive Foreign Investment Company Rules,” gain or loss realized on the sale or other taxable disposition of ADSs will be capital gain or loss and will be a long-term capital gain or loss if the U.S. Holder held the ADSs for more than one year. The amount of the gain or loss will equal the difference between the U.S. Holder’s tax basis in the ADSs disposed of and the amount realized on the disposition, in each case as determined in U.S. dollars. This gain or loss will generally be U.S.-source gain or loss for foreign tax credit purposes. The deductibility of capital losses is subject to limitations.

If the consideration received by a U.S. Holder is not paid in U.S. dollars, the amount realized will be the U.S. dollar value of the payment received determined by reference to the spot rate of exchange on the date of the sale or other disposition. However, if the ADSs are treated as traded on an “established securities market” and a U.S. Holder is either a cash basis taxpayer or an accrual basis taxpayer that has made a special election (which must be applied consistently from year to year and cannot be changed without the consent of the IRS), such U.S. Holder will determine the U.S. dollar value of the amount realized in a non-U.S. dollar currency by translating the amount received at the spot rate of exchange on the settlement date of the sale. If a U.S. Holder is an accrual basis taxpayer that is not eligible to or does not elect to determine the amount realized using the spot rate on the settlement date, such U.S. Holder will recognize foreign currency gain or loss to the extent of any difference between the U.S. dollar amount realized on the date of sale or disposition and the U.S. dollar value of the currency received at the spot rate on the settlement date.

WE STRONGLY URGE YOU TO CONSULT YOUR TAX ADVISOR REGARDING THE IMPACT OF OUR PFIC STATUS ON YOUR INVESTMENT IN THE ADSs AS WELL AS THE APPLICATION OF THE PFIC RULES TO YOUR INVESTMENT IN THE ADSs.

Information Reporting and Backup Withholding

Payments of dividends and sales proceeds that are made within the United States or through certain U.S.-related financial intermediaries generally are subject to information reporting, and may be subject to backup withholding, unless (i) the U.S. Holder is a corporation or other exempt recipient or (ii) in the case of backup withholding, the U.S. Holder provides a correct taxpayer identification number and certifies that it is not subject to backup withholding (generally, by providing a duly completed IRS Form W-9).

Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a U.S. Holder will be allowed as a credit against the holder’s U.S. federal income tax liability and may entitle it to a refund, provided that the required information is timely furnished to the IRS.

Information with Respect to Foreign Financial Assets

Individuals who own “specified foreign financial assets” with an aggregate value in excess of $50,000 may be required to file an information report on IRS Form 8938, “Statement of Specified Foreign Financial Assets,” with respect to such assets with their tax returns. “Specified foreign financial assets” include any financial accounts maintained by foreign financial institutions, as well as any of the following, but only if they are not held in accounts maintained by financial institutions: (i) stocks and securities issued by non-U.S. persons; (ii) financial instruments and contracts held for investment that have non-U.S. issuers or counterparties; and (iii) interests in foreign entities. Such U.S. Holders who fail to timely furnish the required information may be subject to a penalty. Additionally, if a U.S. Holder does not file the required information, the statute of limitations with respect to tax returns of the U.S. Holder to which the information relates may not close until three years after such information is filed. U.S. Holders should consult their tax advisers regarding their reporting obligations with respect to their ownership and disposition of the ADSs.

U.K. Taxation

The following is intended as a general guide to current U.K. tax law and HM Revenue & Customs, or HMRC, published practice applying as at the date of this prospectus (both of which are subject to change at any time, possibly with retrospective effect) relating to the holding of ADSs. It does not constitute legal or tax advice and does not purport to be a complete analysis of all U.K. tax considerations relating to the holding of ADSs, or all of the circumstances in which holders of ADSs may benefit from an exemption or relief from U.K. taxation. It is written on the basis that we do not (and will not) directly or indirectly derive 75% or more of our qualifying asset value from U.K. land, and that we are and remain solely resident in the United Kingdom for tax purposes and will therefore be subject to the U.K. tax regime and not the U.S. tax regime save as set out above under “Material U.S. Federal Income Tax Considerations for U.S. Holders.”

Except to the extent that the position of non-U.K. resident persons is expressly referred to, this guide relates only to persons who are resident for tax purposes solely in the United Kingdom and do not have a permanent establishment, branch, agency (or equivalent) or fixed base in any other jurisdiction with which the holding of the ADSs is connected, or U.K. Holders, who are absolute beneficial owners of the ADSs (where the ADSs are not held through an Individual Savings Account or a Self-Invested Personal Pension) and who hold the ADSs as investments.

This guide may not relate to certain classes of U.K. Holders, such as (but not limited to):

•

persons who are connected with the company;

•

financial institutions;

•

insurance companies;

•

charities or tax-exempt organizations;

•

collective investment schemes;

•

pension schemes;

•

market makers, intermediaries, brokers or dealers in securities;

•

persons who have (or are deemed to have) acquired their ADSs by virtue of an office or employment or who are or have been officers or employees of the company or any of its affiliates; and

•

individuals to whom split-year treatment applies or who are subject to U.K. taxation under the U.K.’s foreign income and gains regime that came into force with effect from April 6, 2025.

The decision of the First-tier Tribunal (Tax Chamber) in HSBC Holdings PLC and The Bank of New York Mellon Corporation v HMRC (2012) cast some doubt on whether a holder of a depositary receipt is the beneficial owner of the underlying shares. However, based on published HMRC guidance we would expect that HMRC will regard a holder of ADSs as holding the beneficial interest in the underlying shares and therefore these paragraphs assume that a holder of ADSs is the beneficial owner of the underlying ordinary shares and any dividends paid in respect of the underlying ordinary shares (where the dividends are regarded for U.K. purposes as that person’s own income) for U.K. direct tax purposes.

THESE PARAGRAPHS ARE A SUMMARY OF CERTAIN U.K. TAX CONSIDERATIONS AND ARE INTENDED AS A GENERAL GUIDE ONLY. IT IS RECOMMENDED THAT ALL HOLDERS OF ADSs OBTAIN ADVICE AS TO THE CONSEQUENCES OF THE ACQUISITION, OWNERSHIP AND DISPOSAL OF THE ADSs IN THEIR OWN SPECIFIC CIRCUMSTANCES FROM THEIR OWN TAX ADVISORS. IN PARTICULAR, NON-U.K. RESIDENT PERSONS ARE ADVISED TO CONSIDER THE POTENTIAL IMPACT OF ANY RELEVANT DOUBLE TAXATION AGREEMENTS.

Dividends

Withholding Tax

Dividends paid by us will not be subject to any withholding or deduction for or on account of U.K. tax.

Income Tax

An individual U.K. Holder may, depending on his or her particular circumstances, be subject to U.K. tax on dividends received from the company. An individual holder of ADSs who is not resident for tax purposes in the United Kingdom should not be chargeable to U.K. income tax on dividends received from the company unless he or she carries on (whether solely or in partnership) a trade, profession or vocation in the United Kingdom through a branch or agency to which the ADSs are attributable. There are certain exceptions for trading in the United Kingdom through independent agents, such as some brokers and investment managers.

All dividends received by an individual U.K. Holder from us or from other sources will form part of that U.K. Holder’s total income for income tax purposes and will constitute the top slice of that income. A nil rate of income tax will apply to the first £500 of taxable dividend income received by the individual U.K. Holder in the tax year 2026/2027. Income within the nil rate band will be taken into account in determining whether income in excess of the £500 tax-free allowance falls within the basic rate, higher rate or additional rate tax bands. In the tax year 2026/2027, dividend income in excess of the tax-free allowance will (subject to the availability of any income tax personal allowance) be taxed at 10.75% to the extent that the excess amount falls within the basic rate tax band, 35.75% to the extent that the excess amount falls within the higher rate tax band and 39.35% to the extent that the excess amount falls within the additional rate tax band.

Corporation Tax

A corporate holder of ADSs who is not resident for tax purposes in the United Kingdom should not be chargeable to U.K. corporation tax on dividends received from us unless it carries on (whether solely or in partnership) a trade in the United Kingdom through a permanent establishment to which the ADSs are attributable.

Corporate U.K. Holders should not be subject to U.K. corporation tax on any dividend received from us so long as the dividends qualify for exemption, which should be the case, although certain conditions must be met. If the conditions for the exemption are not satisfied, or such U.K. Holder elects for an otherwise exempt dividend to be taxable, U.K. corporation tax will be chargeable on the amount of any dividends (at the main rate of 25% for companies with profits in excess of £250,000, or the small profits rate of 19% for companies with profits of £50,000 or less, with marginal relief from the main rate available to companies with profits between £50,000 and £250,000 subject to meeting certain criteria).

Chargeable Gains

A disposal or deemed disposal of ADSs by a U.K. Holder may, depending on the U.K. Holder’s circumstances and subject to any available exemptions or reliefs (such as the annual exemption), give rise to a chargeable gain or an allowable loss for the purposes of U.K. capital gains tax and corporation tax on chargeable gains.

If an individual U.K. Holder who is subject to U.K. income tax at either the higher or the additional rate is liable to U.K. capital gains tax on the disposal of ADSs, the current applicable rate will be 24%. For an individual U.K. Holder who is subject to U.K. income tax at the basic rate and liable to U.K. capital gains tax on such disposal, the current applicable rate would be 18%, save to the extent that any capital gains, when aggregated with the U.K. Holder’s other taxable income and gains in the relevant tax year, exceed the unused basic rate tax band. In that case, the rate currently applicable to the excess would be 24%.

If a corporate U.K. Holder becomes liable to U.K. corporation tax on the disposal (or deemed disposal) of ADSs, U.K. corporation tax would apply (at the main rate of 25% for companies with profits in excess of £250,000, or the small profits rate of 19% for companies with profits of £50,000 or less, with marginal relief from the main rate available to companies with profits between £50,000 and £250,000 subject to meeting certain criteria).

A holder of ADSs which is not resident for tax purposes in the United Kingdom should not normally be liable to U.K. capital gains tax or corporation tax on chargeable gains on a disposal (or deemed disposal) of ADSs unless the person is carrying on (whether solely or in partnership) a trade, profession or vocation in the United Kingdom through a branch or agency (or, in the case of a corporate holder of ADSs, through a permanent establishment) to which the ADSs are attributable. However, an individual holder of ADSs who has ceased to be resident for tax purposes in the United Kingdom for a period of less than five years and who disposes of ADSs during that period may be liable on his or her return to the United Kingdom to U.K. tax on any capital gain realized (subject to any available exemption or relief).

Stamp Duty and Stamp Duty Reserve Tax

The discussion below relates to the holders of our ordinary shares or ADSs wherever resident, however it should be noted that special rules may apply to certain persons such as market makers, brokers, dealers or intermediaries.

Issue of Ordinary Shares

No U.K. stamp duty or stamp duty reserve tax, or SDRT, is payable on the issue of the underlying ordinary shares in the company.

Transfers of Ordinary Shares

An unconditional agreement to transfer ordinary shares in certificated form will normally give rise to a charge to SDRT at the rate of 0.5% of the amount or value of the consideration payable for the transfer. The purchaser of the shares is liable for the SDRT. Transfers of ordinary shares in certificated form are generally also subject to stamp duty at the rate of 0.5% of the amount or value of the consideration given for the transfer (rounded up to the next £5.00). Stamp duty is normally paid by the purchaser. The charge to SDRT will be canceled or, if already paid, repaid (generally with interest), where a transfer instrument has been duly stamped within six years of the charge arising (either by paying the stamp duty or by claiming an appropriate relief) or if the instrument is otherwise exempt from stamp duty.

An unconditional agreement to transfer ordinary shares to, or to a nominee or agent for, a person whose business is or includes the issue of depositary receipts or the provision of clearance services will generally be subject to SDRT (or, where the transfer is effected by a written instrument, stamp duty) at a higher rate of 1.5% of the amount or value of the consideration given for the transfer unless the clearance service has made and maintained an election under section 97A of the U.K. Finance Act 1986, or a section 97A election. It is understood that HMRC regards the facilities of DTC as a clearance service for these purposes and we are not aware of any section 97A election having been made by DTC.

However, no stamp duty or SDRT is payable where the transfer of ordinary shares to a clearance service or depositary receipt system satisfies the conditions of an exemption, which will generally be the case if the transfer occurs in the course of qualifying capital-raising arrangements.

Any stamp duty or SDRT payable on a transfer of ordinary shares to a depositary receipt system or clearance service will in practice generally be paid by the transferors or participants in the clearance service or depositary receipt system.

Issue of ADSs

No U.K. stamp duty or SDRT is payable on the issue of ADSs in the company.

Transfers of ADSs

No SDRT should be required to be paid on a paperless transfer of ADSs through the clearance service facilities of DTC, provided that no section 97A election has been made by DTC, and such ADSs are held through DTC at the time of any agreement for their transfer.

No U.K. stamp duty will in practice be payable on a written instrument transferring an ADS provided that the instrument of transfer is executed and remains at all times outside the United Kingdom. Where these conditions are not met, the transfer of, or agreement to transfer, an ADS could, depending on the circumstances, attract a charge to U.K. stamp duty at the rate of 0.5% of the amount or value of the consideration. If it is necessary to pay stamp duty, it may also be necessary to pay interest and penalties.

LEGAL MATTERS

The validity of our ordinary shares, including ordinary shares in the form of ADSs, being offered by this prospectus and certain other matters of English law will be passed upon for us by Cooley (UK) LLP.

EXPERTS

The consolidated financial statements of Autolus Therapeutics plc appearing in Autolus Therapeutics plc’s Annual Report on Form 10-K for the year ended December 31, 2025 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

The registered business address of Ernst & Young LLP is 1 More London Place, London, SE1 2AF, United Kingdom.

SERVICE OF PROCESS AND ENFORCEMENT OF LIABILITIES

We are incorporated and currently existing under the laws of England and Wales. In addition, certain of our directors and officers reside outside of the United States. As a result, it may be difficult for investors to effect service of process on us or those persons in the United States or to enforce in the United States judgments obtained in United States courts against us or those persons based on the civil liability or other provisions of the United States securities laws or other laws. In addition, uncertainty exists as to whether the courts of England and Wales would:

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recognize or enforce judgments of United States courts obtained against us or our directors or officers predicated upon the civil liabilities provisions of the securities laws of the United States or any state in the United States; or

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entertain original actions brought in England and Wales against us or our directors or officers predicated upon the securities laws of the United States or any state in the United States.

We have been advised by Cooley LLP and Cooley (UK) LLP that there is currently no treaty between (i) the United States and (ii) England and Wales providing for reciprocal recognition and enforcement of judgments of United States courts in civil and commercial matters (although the United States and the United Kingdom are both parties to the New York Convention on the Recognition and Enforcement of Foreign Arbitral Awards) and that a final judgment for the payment of money rendered by any general or state court in the United States based on civil liability, whether predicated solely upon the United States securities laws, would not be automatically enforceable in England and Wales. We have also been advised by Cooley LLP and Cooley (UK) LLP that any final and conclusive monetary judgment for a definite sum obtained against us in United States courts would be treated by the courts of England and Wales as a cause of action in itself and sued upon as a debt at common law so that no retrial of the issues would be necessary, provided that:

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the relevant U.S. court had jurisdiction over the original proceedings according to English conflicts of laws principles at the time when proceedings were initiated;

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the claimant commenced proceedings in the courts of England and Wales and we were duly served with process;

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the U.S. judgment was final and conclusive on the merits in the sense of being final and unalterable in the court that pronounced it and being for a definite sum of money;

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the judgment given by the courts was not in respect of penalties, taxes, fines or similar fiscal or revenue obligations (or otherwise based on a U.S. law that an English court considers to relate to a penal, revenue or other public law), or for a declaration or injunction;

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the judgment was not procured by fraud;

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recognition or enforcement of the judgment in England and Wales would not be contrary to public policy or the Human Rights Act 1998;

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the proceedings pursuant to which judgment was obtained were not contrary to natural justice;

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the U.S. judgment was not arrived at by doubling, trebling or otherwise multiplying a sum assessed as compensation for the loss or damages sustained and not being otherwise in breach of Section 5 of the U.K. Protection of Trading Interests Act 1980, or is a judgment based on measures designated by the Secretary of State under Section 1 of that Act;

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there is not a prior decision of an English court or the court of another jurisdiction on the issues in question between the same parties; and

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the English enforcement proceedings were commenced within the limitation period.

Whether these requirements are met in respect of a judgment based upon the civil liability provisions of the United States securities laws, including whether the award of monetary damages under such laws would constitute a penalty, is an issue for the court making such decision.

Subject to the foregoing, investors may be able to enforce in England and Wales judgments in civil and commercial matters that have been obtained from U.S. federal or state courts. Nevertheless, we cannot assure you that those judgments will be recognized or enforceable in England and Wales.

If an English court gives judgment for the sum payable under a U.S. judgment, the English judgment will be enforceable by methods generally available for this purpose. These methods generally permit the English court discretion to prescribe the manner of enforcement.

In addition, it may not be possible to obtain an English judgment or to enforce that judgment if we are or become subject to any insolvency or similar proceedings, or if we have any set-off or counterclaim against the judgment creditor. Also note that, in any enforcement proceedings, we may raise any counterclaim that could have been brought if the action had been originally brought in England unless the subject of the counterclaim was in issue and denied in the U.S. proceedings.

WHERE YOU CAN FIND MORE INFORMATION

We voluntarily file periodic reports on the forms for U.S. domestic issuers, such as annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, which are more detailed and extensive in certain respects, and which must be filed more promptly, than the forms currently available to foreign private issuers. Despite our election to voluntarily file on U.S. domestic issuer forms, we maintain our status as a foreign private issuer, and accordingly we are exempt from, among other things, the rules under the Exchange Act prescribing the furnishing and content of proxy statements and our officers, directors and principal shareholders are exempt from the reporting and short-swing profit recovery provisions contained in Section 16 of the Exchange Act.

The SEC maintains a website that contains reports and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is www.sec.gov.

We also maintain a website at www.autolus.com through which you can access our SEC filings. The information set forth on our website is not part of this prospectus.

INCORPORATION OF DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” information into this prospectus and any accompanying prospectus supplement the information we have filed with the SEC. Incorporation by reference allows us to disclose important information to you by referring you to those other documents. The information incorporated by reference is an important part of this prospectus, and information that we file later with the SEC will also be deemed to be incorporated by reference into this prospectus and to be a part hereof from the date of filing of such documents and will automatically update and supersede previously filed information, including information contained in this document.

This prospectus and any accompanying prospectus supplement incorporate by reference the documents set forth below that have previously been filed with the SEC:

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Our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, filed with the SEC on March 27, 2026;

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Our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2026 and June 30, 2026, filed with the SEC on May 14, 2026 and August 11, 2026, respectively;

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Our Current Reports on Form 8-K filed with the SEC on January 12, 2026, January 26, 2026, April 16, 2026, April 29, 2026, June 9, 2026, June 29, 2026, August 3, 2026 and August 3, 2026, solely to the extent the information in such reports has been filed (and not furnished) and incorporated by reference into the registration statement of which this prospectus forms a part;

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The description of our ordinary shares and ADSs contained in our Registration Statement on Form 8-A, as filed with the SEC under Section 12(b) of the Exchange Act on June 19, 2018, including any amendment or report filed for the purpose of updating such description (File No. 001-38547).

We are also incorporating by reference all subsequent Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and certain reports on Form 8-K (other than portions of current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) that we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus (if they state that they are incorporated by reference into this prospectus) prior to the termination of the offering of securities under the registration statement of which this prospectus forms a part. In all cases, you should rely on the later information over different information included in this prospectus or any accompanying prospectus supplement.

Unless expressly incorporated by reference, nothing in this prospectus shall be deemed to incorporate by reference information furnished to, but not filed with, the SEC. Copies of all documents incorporated by reference in this prospectus, other than exhibits to those documents unless such exhibits are specifically incorporated by reference in this prospectus, will be provided at no cost to each person, including any beneficial owner, who receives a copy of this prospectus on the written or oral request of that person made to:

Autolus Therapeutics plc

The MediaWorks

191 Wood Lane

White City

London W12 7FP

United Kingdom

+44 20 3829 6230

You may also access these documents on our website, www.autolus.com. The information contained on, or that can be accessed through, our website is not a part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

You should rely only on information contained in, or incorporated by reference into, this prospectus. We have not authorized anyone to provide you with information different from that contained in this prospectus or incorporated by reference in this prospectus. We are not making offers to sell the securities in any jurisdiction in which such an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make such offer or solicitation. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered by this prospectus. Any statement contained in this prospectus or contained in a document incorporated or deemed to be incorporated by reference into this prospectus will be deemed to be modified or superseded to the extent that a statement contained in this prospectus or any subsequently filed supplement to this prospectus, or document deemed to be incorporated by reference into this prospectus, modifies or supersedes such statement.

LOGO

Autolus Therapeutics plc

Up to 3,500,000 American Depositary Shares Representing 3,500,000

Ordinary Shares offered by the Selling Securityholder

PROSPECTUS

September 22, 2026

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