艾卡迪特乐生物制药公司美股招股说明书(2025-09-10版)

We are selling 2,142,858 shares of our common stock. Our common stock is listed on the Nasdaq Global Market under thesymbol “ACTU.”On September 5, 2025, the last reported sales price of our common stock on the Nasdaq Global Market was $8.24per share. As of September 5, 2025, the aggregate market value of our outstanding common stock held by non-affiliates, or public float,was approximately $62.0 million, based on 7,113,902 shares of outstanding common stock held by non-affiliates at a price of $8.72per share, which was the closing price of our common stock on The Nasdaq Stock Market on September 4, 2025. We have not offeredany securities pursuant to General Instruction I.B.6 of Form S-3 during the prior 12-calendar-month period that ends on and includesthe date of this prospectus supplement. Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell securities registeredon this registration statement in a public primary offering with a value exceeding more than one-third of our public float in any 12-month period so long as our public float remains below $75 million. Investing in our securities involves a high degree of risk. Before making an investment decision, you should carefullyreview and consider all of the information set forth in this prospectus supplement, the accompanying base prospectus and thedocuments incorporated by reference herein and therein, including the risks and uncertainties described under “Risk Factors”beginning on page S-3 of this prospectus supplement and the risk factors incorporated by reference into this prospectussupplement and the accompanying base prospectus. Neither theU.S.Securities and Exchange Commission nor any state securities commission has approved ordisapproved of these securities or determined if this prospectus supplement or the accompanying base prospectus is truthful orcomplete. Any representation to the contrary is a criminal offense. (1)Does not include the reimbursement of certain expenses of the underwriter we have agreed to pay. Please see “Underwriting”beginning on page S-10 for additional information regarding the total compensation to be received by the underwriter. We have granted the underwriter a 30-day option to purchase up to an additional 321,428 shares of common stock from us atthe public offering price, less underwriting discounts and commissions. If the underwriter exercises this option in full, the totalunderwriting discounts and commissions payable will be $1,207,500 and the total proceeds to us, before expenses, will be$16,042,502. References to the “underwriter” in this prospectus supplement shall mean Lucid Capital Markets, LLC. The underwriter expects to deliver the shares on or about September 11, 2025. Lucid Capital Markets The date of this prospectus supplement is September 10, 2025. TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTPROSPECTUS SUPPLEMENT SUMMARYTHE OFFERINGRISK FACTORSSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDILUTIONUNDERWRITINGLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE Base Prospectus ABOUT THIS PROSPECTUSPROSPECTUS SUMMARYRISK FACTORSSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDESCRIPTION OF CAPITAL STOCKDESCRIPTION OF DEBT SECURITIESDESCRIPTION OF WARRANTSDESCRIPTION OF UNITSLEGAL OWNERSHIP OF SECURITIESPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement and the accompanying base prospectus are part of a registration statement that we filed with theSecurities and Exchange Commission, or the SEC, utilizing a “shelf” registration process. From time to time, we may conduct anoffering to sell securities under the accompanying base prospectus and a related prospectus supplement that will contain specificinformation about the terms of that offering, including the price, the amount of securities being offered and the plan of distribution.This prospectus supplement describes the specific details regarding this offering and may add, update or change information containedin the accompanying base prospectus. The base prospectus, dated September 8, 2025, including the documents incorporated byreference therein, provides general information about us and our securities, some of which, such as the section entitled “Plan ofDistribution,” may not apply to this offering. This prospectus supplement and the accompanying base prospectus are an offer to sellonly the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. Neither we nor theunderwriter are making offers to sell or solicitations to buy our securities in any jurisdiction in which an offer or solicitation is notauthorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is un