Up to $10,400,000 in Common Stock This Prospectus Supplement (the “Supplement”) amends and supplements the information in the prospectus, dated September 21,“Prior Prospectus”), filed with the Securities and Exchange Commission as a part of our registration statement on Form S-3 (File267550) (the “Registration Statement”), as previously supplemented by prospectus supplements dated December 15, 2022, Februaryand September 19, 2025, relating to the offer and sale of shares of our common stock, having an aggregate offering price of up to $5pursuant to the terms of the Sales Agreement, dated September 15, 2022 (the “Sales Agreement”), with A.G.P./Alliance Global PaA.G.P. This Supplement should be read in conjunction with the Prior Prospectus and all amendments and supplements thereto, and is We are filing this Supplement to amend the Prior Prospectus to update the maximum number of shares that we are eligible to sellRegistration Statement pursuant to the Sales Agreement under General Instruction I.B.6 of Form S-3. As a result of these limitationcurrent public float of our common stock, and in accordance with the terms of the Sales Agreement, we may offer and sell sharcommon stock having an aggregate offering price of up to $10,400,000 from time to time through A.G.P. under the Sales Agreeme We are a “smaller reporting company” as defined under U.S. federal securities laws and are subject to reduced public companyrequirements. Our common stock is listed on the Nasdaq Capital Market (“Nasdaq”) under the symbol “COSM.” The last sale pr As of October 21, 2025, the aggregate market value of our outstanding shares of Common Stock held by non-affiliates, or publicdetermined to be $31,264,804 based on 37,368,221 shares of Common Stock outstanding, of which 29,776,004 are held by non-affiliaprice of $1.05 per share, the closing price of our common stock on October 21, 2025. In no event will the aggregate market value ofsold by us or on our behalf pursuant to General Instruction I.B.6 of Form S-3 during the 12 calendar month period immediately priincluding, the date of any such sale exceed one-third of the aggregate market value of our shares of common stock held by non-afflong as the aggregate market value of our common stock held by non-affiliates is less than $75,000,000. During the prior 12 calend Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page S-9 of this prospectus supplemunder similar headings in the other documents that are incorporated by reference into this prospectus supplement that should be c Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of theseor determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense. A.G.P. The date of this prospectus supplement is December 19, 2025. TABLE OF CONTENTS PaADDITIONAL INFORMATIONCAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTSWHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCEPROSPECTUS SUMMARYTHE OFFERINGRISK FACTORSRECENT DEVELOPMENTSUSE OF PROCEEDSMARKET PRICE OF OUR COMMON STOCKDIVIDEND POLICYDESCRIPTION OF SHARESPLAN OF DISTRIBUTIONSHARES ELIGIBLE FOR FUTURE SALESEC POSITION ON INDEMNIFICATIONLEGAL MATTERSEXPERTSS-2 Table of Contents ADDITIONAL INFORMATION You should rely only on this prospectus supplement, the prospectus, the documents incorporated or deemed to be incorporated byherein or therein, and any free writing prospectus prepared by us or on our behalf. We have not authorized anyone to provideinformation different than that contained or incorporated by reference in this prospectus supplement, the prospectus, and any freprospectus that we have authorized for use in connection with the offering described herein (the "Offering"). We take no responsibilitcan provide no assurance as to the reliability of, any other information that others may give you. You should assume that the inappearing in this prospectus supplement, the prospectus, the documents incorporated by reference herein, and in any free writing prospwe have authorized for use in connection with the Offering is accurate only as of the date of those respective documents. Our business We are offering to sell, and are seeking offers to buy, shares of our Common Stock only in jurisdictions where such offers andpermitted. The distribution of this prospectus supplement and the offering of the shares of our Common Stock in certain jurisdictcertain persons within such jurisdictions may be restricted by law. Persons outside the United States who come into possessioprospectus supplement must inform themselves about and observe any restrictions relating to the offering of the shares of our Comm We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any docuis incorporated by reference in this prospectus supplement were made solely