Amendment: SEC Form SCHEDULE 13D/A filed by 89bio 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 and the Nexus 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.

The information set forth in rows 11 and 13 of the cover pages to this Schedule 13D/A is incorporated by reference.

The information set forth in rows 7 through 10 of the cover pages to this Schedule 13D/A and Item 2 above is incorporated by reference.

None of the Reporting Persons have effected any transactions with respect to the securities of the Issuer since the most recent amendment to this Schedule 13D/A, except that on October 30, 2025, the Reporting Persons tendered all of their shares of Common Stock of the Issuer, consisting of 19,554,319 shares of Common Stock held directly by the Fund and 335,364 shares of Common Stock held directly by the Nexus Fund, pursuant to the terms of an Agreement and Plan of Merger, dated as of September 17, 2025 (the "Merger Agreement"), by and among the Issuer, Roche Holdings, Inc. ("Parent") and Bluefin Merger Subsidiary, Inc., a wholly owned subsidiary of Parent ("Merger Sub"), at an offer price per share of (i) $14.50 per share in cash, without interest (the "Closing Amount") less any required withholding taxes, plus (ii) one non-tradeable contingent value right (each, a "CVR") representing the right to receive certain contingent payments of up to an aggregate amount of $6.00 per share, in cash, without interest less any required withholding taxes, upon the achievement of specified milestones on or prior to the applicable milestone outside dates, subject to and in accordance with the terms of the Contingent Value Rights Agreement (the "CVR Agreement"). After completion of the tender offer, Purchaser merged with and into the Issuer (the "Merger"), effective as of October 30, 2025 (the "Effective Time"), with the Issuer continuing as the surviving entity and a wholly owned subsidiary of Parent. As of immediately prior to and conditioned upon the occurrence of the Effective Time, and without any action on the part of any holder thereof, pursuant to the Merger Agreement each then-outstanding company-issued warrant that had an exercise price per share that was less than the Closing Amount (each, an "In the Money Warrant"), including 4,331,081 pre-funded warrants ("PFWs") held by the Fund, through which the Fund had the right to acquire 4,331,081 shares of Common Stock, was automatically deemed to be exercised into the number of shares subject to such In the Money Warrant and converted automatically into the right to receive: (A) an amount in cash, without interest and subject to deduction for required withholding taxes, equal to the product of (x) the excess of the Closing Amount over the exercise price of such In the Money Warrant and (y) the number of shares subject to such In the Money Warrant, plus (B) one CVR with respect to each share subject to such In the Money Warrant. As of immediately prior to and conditioned upon the occurrence of the effective time of the Merger, pursuant to the Merger Agreement, each outstanding option to purchase Shares (each, an "Option"), including a total of 180,450 stock options (right to buy) held by Derek DiRocco for the benefit of RA Capital, became fully vested and exercisable, and to the extent not exercised prior to the effective time of the Merger, was cancelled and converted into the right to receive (i) an amount in cash (without interest and subject to deduction for any required withholding taxes) equal to the product of (A) an amount equal to the excess of the Closing Amount over the exercise price per Share with respect to such Option and (B) the number of Shares subject to such Option plus (ii) one CVR with respect to each Share subject to such Option (the "Option Consideration"); provided, however, that if the exercise price per Share of any Option was equal to or greater than the Closing Amount, but less than $20.50 (any such option, an "Out of the Money Option"), such Out of the Money Option was not entitled to any payment of the Closing Amount in respect thereof and each Out of the Money Option was converted into the right to receive the CVR included in the Option Consideration with respect to each Share underlying such Out of the Money Option and became entitled to receive, at each time a milestone payment becomes due and payable under the terms of the CVR Agreement, an amount in cash equal to the product of (i) the number of Shares subject to such Out of the Money Option, and (ii) the amount, if any, by which (A) the Closing Amount plus the applicable milestone payment plus any other milestone payment that previously became due and payable under the terms of the CVR Agreement exceeds (B) the exercise price per Share with respect to such Out of the Money Option plus the amounts, if any, paid to such Option holder with respect to such CVR in respect of any milestone payments that previously became due and payable under the terms of the CVR Agreement; provided further, that any Option with an exercise price that was equal to or greater than $20.50, was cancelled immediately prior to the effective time of the Merger without the receipt of any payment of the Closing Amount or CVR in respect thereof.

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 shares of Common Stock subject to this 13D/A.

The Reporting Persons ceased to beneficially own greater than 5% of the Common Stock on October 30, 2025.

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 March 3, 2025). Exhibit 99.2 Offer to Purchase, dated as of October 1, 2025 (incorporated as Exhibit 99.(a)(1)(A) to the Issuer's Tender Offer Statement by Third Party filed with the Securities and Exchange Commission on October 1, 2025).