Amendment: SEC Form SCHEDULE 13D/A filed by Cidara Therapeutics Inc.

The address of the principal business office of each of the Reporting Persons is 200 Berkeley Street, 18th Floor, Boston, MA 02116.

The Fund is a private investment vehicle. RA Capital provides investment management services to the Fund. The principal occupation of each of Dr. Kolchinsky and Mr. Shah is investment management.

During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree of final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

See Item 6 of the cover pages.

Item 4 of the Statement is hereby amended and supplemented as follows: Merger Agreement On November 13, 2025, the Issuer entered into an Agreement and Plan of Merger by and among the Issuer, Merck Sharp & Dohme LLC, a New Jersey limited liability company ("Parent") and Caymus Purchaser, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Purchaser") (the "Merger Agreement"). Pursuant to the Merger Agreement, upon the terms and subject to the conditions thereof, Parent will cause Purchaser to commence a cash tender offer (the "Offer") no later than December 4, 2025. The Offer will consist of an offer to purchase (i) all of the outstanding shares of common stock of the Issuer (the "Common Shares"), at a price of $221.50 per Common Share (the "Common Share Offer Price") and (ii) all of the outstanding shares of Series A Preferred Stock of the Issuer, par value $0.0001 per share (the "Series A Shares" and together with the Common Shares, the "Shares"), at a price of $15,505.00 per Series A Share (the "Series A Offer Price"), in each case, in cash, without interest and subject to any applicable withholding of taxes. The obligation of Purchaser to accept for payment, and pay for, Shares validly tendered (and not validly withdrawn) pursuant to the Offer is subject to satisfaction or waiver, to the extent permitted under applicable legal requirements, of certain conditions set forth in the Merger Agreement, including, among other things, (i) there being validly tendered and not validly withdrawn Common Shares and Series A Shares that, considered together with all other Shares (if any) beneficially owned by Parent or any of its wholly owned subsidiaries (but excluding Shares tendered pursuant to guaranteed delivery procedures, if permitted by the terms of the Offer, that have not yet been "received" by the "depositary", as such terms are defined by Section 251(h)(6) of the General Corporation Law of the State of Delaware (the "DGCL")), would represent (with respect to such Series A Shares, on an as-converted to Common Share basis) one more than 50% of the total number of Shares outstanding at the time of the expiration of the Offer and (ii) there being received, terminated or expired, as the case may be, any consent, approval or clearance with respect to, or termination or expiration of any applicable mandatory waiting period (and any extension thereof) imposed under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. Parent's and Purchaser's obligations to consummate the Offer are not subject to a condition that any financing be received by Parent or Purchaser for the consummation of the transactions contemplated by the Merger Agreement. As soon as practicable following consummation of the Offer, subject to the terms and conditions of the Merger Agreement and in accordance with Section 251(h) of the DGCL, Purchaser will merge with and into the Issuer (the "Merger" and, together with the Offer and the other transactions contemplated by the Merger Agreement, the "Transactions"), with the Issuer surviving the Merger as a wholly owned subsidiary of Parent in accordance with the DGCL. At the effective time of the Merger (the "Effective Time"), each Common Share then outstanding (other than Common Shares (a) held by the Issuer (or in the Issuer's treasury), Parent, Purchaser, any other direct or indirect wholly owned subsidiary of Parent or the Issuer, or by stockholders of the Issuer who have properly exercised and perfected their statutory rights of appraisal under the DGCL, or (b) irrevocably accepted for purchase in the Offer) will be converted into the right to receive the Common Share Offer Price (the "Common Share Merger Consideration"), without interest and subject to any applicable withholding of taxes. At the Effective Time, each Series A Share then outstanding (other than Series A Shares (a) held by the Issuer (or in the Issuer's treasury), Parent, Purchaser, any other direct or indirect wholly owned subsidiary of Parent or the Issuer, or by stockholders of the Issuer who have properly exercised and perfected their statutory rights of appraisal under the DGCL, or (b) irrevocably accepted for purchase in the Offer) will be converted into the right to receive the Series A Offer Price, without interest and subject to any applicable withholding of taxes. Each warrant to purchase Common Shares, including Pre-Funded Warrants, that is outstanding and unexercised as of immediately prior the Effective Time, whether vested or unvested, will be treated as being simultaneously cashless exercised in accordance with the terms and conditions specified in the applicable warrant and subject to any applicable withholding of taxes. Each of the Company's stock options that is outstanding as of immediately prior to the Effective Time will accelerate and become fully vested and exercisable effective immediately prior to, and contingent upon the occurrence of, the Effective Time. As of the Effective Time, each option that is then outstanding and unexercised will be cancelled and converted into the right to receive cash, without interest, in an amount equal to the product of (i) the total number of Common Shares subject to the fully vested option immediately prior to the Effective Time, multiplied by (ii) the excess, of (x) the Common Share Merger Consideration over (y) the exercise price payable per Common Share under such option, subject to any applicable withholding of taxes. Any option that has an exercise price that equals or exceeds the Common Share Merger Consideration will be cancelled for no consideration. Upon the closing of the Merger, the Issuer's common stock will be deregistered under the Securities and Exchange Act of 1934, as amended, and cease to be listed for trading on the Nasdaq Stock Market. Tender and Support Agreement On November 13, 2025, in connection with the Merger Agreement, certain stockholders of the Issuer, including the Fund (collectively, the "Supporting Stockholders") entered into Tender and Support Agreements with Parent and Purchaser (each, a "Support Agreement"). Under the terms of the Support Agreement, the Fund has agreed, among other things, to tender its Common Shares and Series A Shares in the Offer, vote its shares in favor of the Merger at a special meeting of the Issuer's stockholders, if there is one, and, subject to certain exceptions, not to transfer any of its shares. The description of the Support Agreement herein is not complete and is qualified in its entirety by reference to the full text of the Form of Support Agreement, which is filed herewith as Exhibit 99.2 and incorporated herein by reference.

Rows 11 and 13 of each Reporting Person's cover page to this Schedule 13D/A set forth the aggregate number of Common Shares and percentages of the shares of common stock beneficially owned by such Reporting Person and are incorporated by reference. The percentage set forth in each row 13 is based upon 31,439,371 shares of common stock outstanding as of November 3, 2025, as disclosed in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on November 6, 2025, and giving effect to stock options, to the extent exercisable within 60 days hereof, as referenced herein.

Rows 7 through 10 of each Reporting Person's cover page to this Schedule 13D/A set forth the number of Common Shares as to which such Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition and are incorporated by reference.

Except as set forth herein, none of the Reporting Persons has effected any transactions with respect to the securities of the Issuer since the most recent amendment to this Schedule 13D/A.

No person (other than the Reporting Persons) is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities subject to this Statement.

Not Applicable.

Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 99.1 to the Reporting Persons' Schedule 13D/A filed with the SEC on June 30, 2025). Exhibit 99.2 Form of Tender and Support Agreement (incorporated by reference to Exhibit 2.1 to the Issuer's Current Report on Form 8-K (File No. 001-36912), filed on November 14, 2025).