Iterum Therapeutics plc美股招股说明书(2025-10-16版)

Ordinary Shares (not to exceed 21,756,057 Ordinary Shares) We previously entered into an at the market offering agreement, dated as of October7, 2022, or the sales agreement, with H.C. Wainwright& Co., LLC, or the Sales Agentor Wainwright, relating to the sale of our ordinary shares, nominal value $0.01 per share offered by this prospectus supplement and the accompanying prospectus. In accordancewith the terms of the sales agreement, we may offer and sell from time to time through Wainwright acting as our sales agent a number of our ordinary shares that does not exceedthe lesser of (1)a number or dollar amount registered on the registration statement pursuant to which the offering is being made, (2)the number of our authorized but unissuedordinary shares (after deducting the number of ordinary shares issuable upon exercise, conversion or exchange of our outstanding securities or otherwise reserved for futureissuance), or (3)the number or dollar amount of ordinary shares that would cause this offering to not satisfy the requirements for use of FormS-3,including, if applicable, GeneralInstruction I.B.6 of FormS-3. As of October16, 2025, we had 21,756,057 authorized but unissued ordinary shares (after deducting the number of ordinary shares issuable upon exercise, conversion orexchange of our outstanding securities or otherwise reserved for future issuance). Based on 21,756,057 authorized ordinary shares available for issuance and an assumed offeringprice per share of $0.7377, which was the last reported sale price of our ordinary shares on the Nasdaq Capital Market on October15, 2025, we would be able to issue and sellshares under our sales agreement for a maximum of $16,049,443, notwithstanding the $20,000,000 maximum aggregate offering amount set forth in this prospectus supplement. Inno event will we sell, pursuant to the registration statement of which this prospectus forms a part, more ordinary shares than we have available and authorized for issuance. Pursuant to a prospectus supplement dated December10, 2024, or the prior prospectus supplement, to our Registration Statement on FormS-3(FileNo.333-267795),weregistered the issuance and sale of up to $25,000,000 of our ordinary shares issuable pursuant to the sales agreement. This prospectus supplement supersedes the prior prospectussupplement relating to the offer and sale of our ordinary shares in accordance with the sales agreement. Accordingly, the up to $4,775,345 of our ordinary shares remainingavailable to be sold under the prior prospectus supplement as of the date hereof will no longer be offered and sold under the prior prospectus supplement and will instead be offeredand sold under this prospectus supplement and the accompanying prospectus. As of the date of this prospectus supplement, we have issued and sold our ordinary shares foraggregate gross sale proceeds of approximately $36.2million pursuant to the sales agreement under both the prior prospectus supplement and an additional prospectus, datedOctober17, 2022, as amended and supplemented by prospectus supplements dated October11, 2024, October28, 2024 and October30, 2024. Sales of our ordinary shares, if any, under this prospectus supplement and the accompanying prospectus may be made by any method permitted that is deemed to be an “atthe market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, or the Securities Act, including sales made directly on or through theNasdaq Capital Market, the existing trading market for our ordinary shares, or any other existing trading market in the United States for our ordinary shares, sales made to orthrough a market maker other than on an exchange or otherwise, directly to the Sales Agent as principal, in negotiated transactions at market prices prevailing at the time of sale orat prices related to such prevailing market prices, and/or in any other method permitted by law. Wainwright will act as our sales agent using commercially reasonable efforts to sellon our behalf all of the ordinary shares requested to be sold by us, consistent with their normal trading and sales practices, on mutually agreed terms between Wainwright and us.There is no arrangement for funds to be received in any escrow, trust or similar arrangement. We will pay Wainwright a commission equal to 3.0% of the gross sales price per share issued by us and sold through it as Sales Agent. In connection with the sales of ourordinary shares on our behalf, Wainwright will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation paid to Wainwright will bedeemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to Wainwright against certain liabilities, including liabilitiesunder the Securities Act. See “Plan of Distribution” beginning on pageS-33of this prospectus supplement. Our ordinary shares trade on the Nasdaq Capital Market under the symbol “IT