04280AAC4

Item 4 of the Original Schedule 13D is hereby amended by adding the following: On August 13, 2025, Sarepta Investments sold 9,265,312 shares of the Issuer's Common Stock at a price of $18.79 per share in a privately negotiated block trade pursuant to Rule 144 of the Securities Act of 1933, as amended (the "Secondary Sale"). Also on August 13, 2025, concurrently with the Secondary Sale, Sarepta, Sarepta Investments and the Issuer entered into a Letter Agreement (the "Letter Agreement") pursuant to which the Issuer agreed to redeem and acquire from Sarepta Investments 2,660,989 shares of the Issuer's Common Stock (the "Redemption") in satisfaction of the obligation of Sarepta to pay the Issuer $49,999,983.31 of the DM1 First Development Milestone Payment (as such term is defined in Section 8.3.1(a)(i) of the Collaboration Agreement). The foregoing description of the Letter Agreement is not complete and is subject to and qualified in its entirety by reference to the full text of such agreement, which is attached as Exhibit 99.5 hereto and incorporated herein by reference.

Item 4 of the Original Schedule 13D is hereby amended by adding the following: On August 13, 2025, Sarepta Investments sold 9,265,312 shares of the Issuer's Common Stock at a price of $18.79 per share in a privately negotiated block trade pursuant to Rule 144 of the Securities Act of 1933, as amended (the "Secondary Sale"). Also on August 13, 2025, concurrently with the Secondary Sale, Sarepta, Sarepta Investments and the Issuer entered into a Letter Agreement (the "Letter Agreement") pursuant to which the Issuer agreed to redeem and acquire from Sarepta Investments 2,660,989 shares of the Issuer's Common Stock (the "Redemption") in satisfaction of the obligation of Sarepta to pay the Issuer $49,999,983.31 of the DM1 First Development Milestone Payment (as such term is defined in Section 8.3.1(a)(i) of the Collaboration Agreement). The foregoing description of the Letter Agreement is not complete and is subject to and qualified in its entirety by reference to the full text of such agreement, which is attached as Exhibit 99.5 hereto and incorporated herein by reference.