As filed with the Securities and Exchange Commission on March 28, 2024

Registration No. 333-     

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Autolus Therapeutics plc

(Exact name of registrant as specified in its charter)

Not Applicable

(Translation of registrant’s name into English)

The MediaWorks

191 Wood Lane

White City

London W12 7FP

United Kingdom

Tel: +44 20 3829 6230

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

Autolus Inc.

15810 Gaither Drive

Gaithersburg, Maryland 20877

Tel: +1 240 801 3830

(Name, address and telephone number of agent for service)

Copies of all communications, including communications sent to agent for service, should be sent to:

APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: From time to time after the effective date of this registration statement.

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

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

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

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

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

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

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

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

PROSPECTUS

33,333,333 American Depositary Shares

Representing 33,333,333 Ordinary Shares

This prospectus relates to the resale from time to time by the selling securityholder identified in this prospectus, or the selling securityholder, of up to 33,333,333 American Depositary Shares, or ADSs, representing 33,333,333 ordinary shares, with a nominal value of $0.000042 per share, or the ordinary shares, of Autolus Therapeutics plc, or the Company. We are not selling any securities and will not receive any proceeds from the sale of the securities under this prospectus.

The selling securityholder acquired the ADSs in a private placement transaction that closed on February 13, 2024. We are filing the registration statement of which this prospectus forms a part to fulfill our contractual obligations to the selling securityholder to provide for the registration with the Securities and Exchange Commission, or the SEC, of the resale by the selling securityholder of the ADSs. See “Selling Securityholder” beginning on page 14 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 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. The net proceeds received from the sale or other disposition of our securities by the selling securityholder, if any, is unknown.

We have agreed, pursuant to a registration rights agreement that we have entered into with the selling securityholder, to bear all of the expenses incurred with the registration of these ADSs. The selling securityholder will pay or assume discounts, commissions, fees of underwriters, selling brokers or dealer managers and similar expenses, if any, incurred for the sale of the ADSs.

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 March 26, 2024, the closing sale price of the ADSs on Nasdaq was $6.17.

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, 2023, 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.” This prospectus may not be used to sell our securities unless accompanied by a prospectus supplement.

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

The date of this prospectus is March 28, 2024.

TABLE OF CONTENTS

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ABOUT THIS PROSPECTUS

This prospectus is part of an automatically effective registration statement on Form S-3 that we have filed with the SEC as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act of 1933, as amended, or the Securities Act. 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 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 supplement 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 ordinary shares 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.

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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 most recent Annual Report on Form 10-K and subsequently filed Quarterly Reports on Form 10-Q, as updated by our subsequent filings, 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.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents we have filed with the SEC that are incorporated herein by reference contain forward-looking statements within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, that involve substantial risks and uncertainties. In some cases, you can identify forward-looking statements by the words “may,” “might,” “will,” “could,” “would,” “should,” “expect,” “intend,” “plan,” “objective,” “anticipate,” “believe,” “estimate,” “predict,” “potential,” “continue” and “ongoing,” or the negative of these terms, or other comparable terminology intended to identify statements about the future. 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 such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. Forward-looking statements include, but are not limited to, statements about:

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You should refer to the “Risk Factors” section of this prospectus and similarly captioned sections included in the 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, there can be no assurance 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, these statements should not be regarded 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.

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USE OF PROCEEDS

The proceeds from the sale or other disposition of our ADSs covered by this prospectus are solely for the account of the selling securityholder. Accordingly, we will not receive any proceeds from the sale or other disposition of such ADSs, and the net proceeds received from the sale or other disposition of such ADSs by the selling securityholder, if any, is unknown. We will, however, bear the costs incurred in connection with the registration of these ADSs.

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PLAN OF DISTRIBUTION

BioNTech SE and its donees, pledgees, transferees, distributees, or other successors-in-interest, or, collectively, the selling securityholder, selling the 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:

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 securityholders to include the pledgee, transferee, or other successors-in-interest as the selling securityholders 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 their short positions, or loan or pledge securities to broker-dealers

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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 conform 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 they earn 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 the selling securityholder, dated as of February 6, 2024, 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.

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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.

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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, 2023, filed with the SEC on March 21, 2024, and the full text of our articles of association, filed as Exhibit 4.1 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.

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SELLING SECURITYHOLDER

The ADSs being offered by the selling securityholder are those that we sold to BioNTech in February 2024 pursuant to a securities purchase agreement entered into concurrently with a registration rights agreement, letter agreement and a license and option agreement, which we collectively refer to as the BioNTech Agreements. For additional information regarding the BioNTech Agreements and our relationship with the selling securityholder, see “Business—Our License and Option Agreement with BioNTech SE” in Part I, Item 1 of our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the SEC on March 21, 2024, as well as any amendments thereto disclosed in our subsequent filings with the SEC. We are registering the ADSs in order to permit the selling securityholder to offer its ordinary shares in the form of ADSs for resale from time to time. The ADSs being registered are subject to a contractual restriction that prevents sale or transfer, subject to customary exceptions, for the period ending six months from issuance.

When we refer to “selling securityholder” in this prospectus, we mean the securityholder listed in the table below as well as its donees, pledgees, transferees, distributees, or other successors-in-interest.

The table below sets forth, to our knowledge, information about the selling securityholder as of March 18, 2024.

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 shares of 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 March 18, 2024. 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 ADSs since the date on which the information in the table below is presented. Information about the selling securityholder may change over time.

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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 consequences that may be relevant in light of a U.S. Holder’s particular circumstances, including state and local tax consequences, estate tax consequences, alternative minimum tax consequences, the potential application of the Medicare contribution tax, and tax consequences applicable to U.S. Holders subject to special rules, such as

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.

U.S. Holders that own (directly, indirectly, or constructively through the application of attribution rules) 10% or more of our total combined voting power or value could be subject to adverse U.S. federal income tax consequences pursuant to the controlled foreign corporation rules due to our ownership of a U.S. subsidiary. Such prospective holders should consult with their tax advisors as to the tax consequences of acquiring, owning and disposing of our ADSs.

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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.

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:

U.S. Holders are encouraged to consult their tax advisers concerning the U.S. federal, state, local and foreign 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 owner of the underlying ordinary shares that such ADSs represent. Accordingly, no gain or loss will be recognized if a U.S. Holder exchanges ADSs for the underlying shares represented by those ADSs. The U.S. Treasury has expressed concern that parties to whom ADSs are released before shares are delivered to the Depositary or intermediaries in the chain of ownership between holders and the issuer of the security underlying the ADSs, may be taking actions that are inconsistent with the claiming of foreign tax credits by U.S. Holders of ADSs. These actions would also be inconsistent with the claiming of the reduced rate of tax, described below, applicable to dividends received by certain non-corporate U.S. Holders. Accordingly, the creditability of non-U.S. withholding taxes (if any), and the availability of the reduced tax rate for dividends received by certain non-corporate U.S. Holders, each described below, could be affected by actions taken by such parties or intermediaries.

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.

A non-U.S. corporation will be classified as a PFIC for any taxable year in which, after applying certain look-through rules, either:

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We will be treated as owning our proportionate share of the assets and earning our proportionate share of the income of any other corporation, the equity of which we own, directly or indirectly, 25% or more (by value).

We believe we were a PFIC for our taxable year ended December 31, 2023 and we may be a PFIC in future taxable years. No assurances regarding our PFIC status can be provided for any past, current or future taxable years. 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. 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. Our U.S. counsel expresses no opinion with respect to our PFIC status for our taxable year ended December 31, 2023 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. Holders 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. For our taxable year ended December 31, 2023, we intend to provide U.S. Holders on our website such information as the IRS may require, including a PFIC annual information statement, in order to enable U.S. Holders to make a QEF Election. 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.

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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 purging election to cause a deemed sale of the ADSs at their fair market value in conjunction with a QEF election (however, as discussed above, such elections are expected and assumed not to be available) 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 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, and you are a holder of ADSs, 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 the 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 Internal Revenue Service, or 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

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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 with respect to the U.S. Holder 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

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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 supplement (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 (and, in the case of individuals, domiciled or deemed domiciled and to whom split-

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year treatment does not apply) 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):

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 OR DOMICILED 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.

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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 £1,000 of taxable dividend income received by the individual U.K. Holder in the tax year 2023/2024. Income within the nil rate band will be taken into account in determining whether income in excess of the £1,000 tax-free allowance falls within the basic rate, higher rate or additional rate tax bands. Dividend income in excess of the tax-free allowance will (subject to the availability of any income tax personal allowance) be taxed at 8.75% to the extent that the excess amount falls within the basic rate tax band, 33.75% 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. The annual tax-free dividend allowance would be reduced to £500 with effect from April 2024.

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 20%. 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 10%, 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 20%.

If a corporate U.K. Holder becomes liable to U.K. corporation tax on the disposal (or deemed disposal) of ADSs, the 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).

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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 generally 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.

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LEGAL MATTERS

The validity of our ordinary shares, including ordinary shares in the form of ADSs, being offered by this prospectus 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, 2023 have been audited by Ernst & Young LLP (PCAOB ID: 01438), 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 R+ Building, 2 Blagrave Street, Reading RG1 1AZ, United Kingdom.

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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:

We have been advised by 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 (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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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.

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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.

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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:

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.

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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.

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

The following table sets forth the various expenses to be incurred in connection with the sale and distribution of the securities being registered hereby, all of which will be borne by the registrant (except any underwriting discounts and commissions and expenses incurred by the selling securityholder for brokerage, accounting, tax or legal services or any other expenses incurred by the selling securityholder in disposing of its shares). All amounts shown are estimates except the SEC registration fee.

Item 15. Indemnification of Directors and Officers.

Subject to the U.K. Companies Act 2006, members of the registrant’s board of directors and its officers have the benefit of the following indemnification provisions in the registrant’s articles of association:

Current and former members of the registrant’s board of directors or officers shall be indemnified against all relevant loss, including any liability incurred by him in defending any civil or criminal proceedings, in which judgment is given in his favour or in which he is acquitted or the proceedings are otherwise disposed of without any finding or admission of any material breach of duty on his part or in connection with any application in which the court grants him relief from liability for negligence, default, breach of duty or breach of trust in relation to the registrant’s or the group’s affairs. In the case of current or former members of the registrant’s board of directors, in compliance with the U.K Companies Act of 2006, there shall be no entitlement to reimbursement as referred to above for (i) any liability incurred to the registrant or any associated company, (ii) the payment of a fine imposed in any criminal proceeding or a penalty imposed by a regulatory authority for non-compliance with any requirement of a regulatory nature, (iii) the defense of any criminal proceeding if the member of the registrant’s board of directors is convicted, (iv) the defense of any civil proceeding brought by the registrant or an associated company in which judgment is given against the director, and (v) any application for relief under the statutes of the United Kingdom and any other statutes that concern and affect the registrant as a company in which the court refuses to grant relief to the director.

The registrant may provide any current or former director or officer with funds to meet expenditure incurred or to be incurred by them in connection with any proceedings or application referred to above and otherwise may take any action to enable any such relevant officer to avoid incurring such expenditure.

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Item 16. Exhibits.

The following exhibits are filed with this registration statement or are incorporated herein by reference.

Item 17. Undertakings.

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20 percent change in the maximum aggregate offering price set forth in the Filing Fee Table in the effective registration statement; and

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

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(5) That, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s Annual Report pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s Annual Report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(6) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

II-3

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of London, United Kingdom, on March 28, 2024.

POWER OF ATTORNEY

We, the undersigned officers and directors of Autolus Therapeutics plc, hereby severally constitute and appoint Christian Itin and Alex Driggs our true and lawful attorneys with full power to any of them, and to each of them singly, to sign for us and in our names in the capacities indicated below the Registration Statement on Form S-3 filed herewith and any and all amendments (including post-effective amendments) to said Registration Statement, and to file or cause to be filed the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, and generally to do all such things in our name and on our behalf in our capacities as officers and directors to enable Autolus Therapeutics plc to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming all that said attorneys, and each of them, or their substitute or substitutes, shall do or cause to be done by virtue hereof.

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

II-4

SIGNATURE OF AUTHORIZED U.S. REPRESENTATIVE

Pursuant to the Securities Act of 1933, the undersigned, the duly authorized representative in the United States of Autolus Therapeutics plc has signed this registration statement or amendment thereto on March 28, 2024.

II-5

Exhibit 5.1

Claire Keast-Butler

+44 (0) 20 7556 4211

ckeastbutler@cooley.com

Autolus Therapeutics plc

The Mediaworks

191 Wood Lane

London W12 7FP

United Kingdom

28 March 2024

Ladies and Gentlemen:

For the purpose of issuing this letter, we have reviewed the following documents only:

Cooley (UK) LLP 22 Bishopsgate London EC2N 4BQ UK

t: +44 (0) 20 7583 4055 f: +44 (0) 20 7785 9355 cooley.com

Cooley (UK) LLP is a limited liability partnership and is registered in England and Wales with registered number OC395270. Our registered office is at the address above.

Cooley (UK) LLP is authorised and regulated by the Solicitors Regulation Authority (SRA number 617791). A list of the members of Cooley (UK) LLP and their

professional qualifications is open to inspection at its registered office. The word ‘partner,’ used in relation to Cooley (UK) LLP, refers to a member of Cooley (UK) LLP or

an employee or consultant of Cooley (UK) LLP (or any affiliated firm) of equivalent standing.

Page Two

In addition to examining the documents referred to in paragraph 2 (Documents), we have carried out the following searches only:

Subject to the assumptions set out in paragraph 5 (Assumptions), the scope of the opinions set out in paragraph 6 (Scope of Opinions) and the reservations set out in paragraph 7 (Reservations), we are of the opinion that as at the date of this letter:

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In giving the opinions in this letter, we have assumed (without making enquiry or investigation) that:

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since notice of these matters may not be filed with the Registrar of Companies in England and Wales immediately and, when filed, may not be entered on the public database or recorded on the public microfiches of the relevant company immediately.

In addition, such a company search is not capable of revealing, prior to the making of the relevant order, whether or not a winding-up petition or a petition for an administration order has been presented.

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Yours faithfully

/s/ Cooley (UK) LLP

Cooley (UK) LLP

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the reference to our firm under the caption “Experts” in the Registration Statement (Form S-3) and related Prospectus of Autolus Therapeutics plc for the registration of 33,333,333 American Depository Shares, representing 33,333,333 Ordinary shares and to the incorporation by reference therein of our report dated March 21, 2024, with respect to the consolidated financial statements of Autolus Therapeutics plc, included in its Annual Report (Form 10-K) for the year ended December 31, 2023, filed with the Securities and Exchange Commission.

Exhibit 107

Calculation of Filing Fee Table

Form S-3

(Form Type)

Autolus Therapeutics plc

(Exact Name of Registrant as Specified in its Charter)

Table 1: Newly Registered Securities