X0202 SCHEDULE 13G 0001281446 XXXXXXXX LIVE Ordinary shares, par value $0.0001 per share 04/17/2026 0002112446 JATT II Acquisition Corp. G50765109 153 Central Avenue C/O 56 Westfield NJ 07091 Rule 13d-1(c) Great Point Partners, LLC DE 0.00 500000.00 0.00 500000.00 500000.00 N 6.41 IA OO Dr. Jeffrey R. Jay, M.D. X1 0.00 500000.00 0.00 500000.00 500000.00 N 6.41 HC IN Ms. Lillian Nordahl X1 0.00 500000.00 0.00 500000.00 500000.00 N 6.41 HC IN JATT II Acquisition Corp. 153 Central Avenue, C/O 56, Westfield, NJ 07091 Great Point Partners, LLC Dr. Jeffrey R. Jay, M.D. Ms. Lillian Nordahl The Reporting Persons have entered into a Joint Filing Agreement, dated April 24, 2026, a copy of which is filed with this SCHEDULE 13G as Exhibit A, pursuant to which the Reporting Persons have agreed to file this statement jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act. The address of the principal business office of each of the Reporting Persons is 165 Mason Street, 3rd Floor Greenwich, CT 06830 Great Point Partners, LLC is a limited liability company organized under the laws of the State of Delaware. Dr. Jeffrey R. Jay, M.D. is a citizen of the United States. Ms. Lillian Nordahl is a citizen of the United States. Y 500,000 6.41% 0 500,000 0 500,000 The information required by Items 4(a) - (c) is set forth in Rows (5) - (11) of the cover pages for the Reporting Persons and is incorporated herein by reference. The percentage set forth in Row (11) of the cover pages for the Reporting Persons are based on a total of 7,800,000 shares outstanding, as reported by the Issuer in its Form 424B Prospectus filed with the Securities and Exchange Commission (the "SEC") on April 17, 2026. Biomedical Value Fund, L.P. ("BVF") is the record holder of 330,000 shares (the "BVF Shares"). Great Point Partners, LLC ("Great Point") is the investment manager of BVF, and by virtue of such status may be deemed to be the beneficial owner of the BVF Shares. Each of Dr. Jeffrey R. Jay, M.D. ("Dr. Jay"), as Senior Managing Member of Great Point, and Ms. Lillian Nordahl ("Ms. Nordahl"), as Managing Director of Great Point, has voting and investment power with respect to the BVF Shares, and therefore may be deemed to be the beneficial owner of the BVF Shares. Biomedical Offshore Value Fund, Ltd. ("BOVF") is the record holder of 170,000 shares (the "BOVF Shares"). Great Point is the investment manager of BOVF, and by virtue of such status may be deemed to be the beneficial owner of the BOVF Shares. Each of Dr. Jeffrey R. Jay, M.D. ("Dr. Jay"), as Senior Managing Member of Great Point, and Ms. Lillian Nordahl ("Ms. Nordahl"), as Managing Director of Great Point, has voting and investment power with respect to the BOVF Shares, and therefore may be deemed to be the beneficial owner of the BOVF Shares. Notwithstanding the above, Great Point, Dr. Jay and Ms. Nordahl disclaim beneficial ownership of the BVF Shares and the BOVF Shares, except to the extent of their respective pecuniary interests. Y N See Item 4. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned hereby agree as follows: (i) Each of them is individually eligible to use the SCHEDULE 13G to which this Exhibit is attached, and such SCHEDULE 13G is filed on behalf of each of them; and (ii) Each of them is responsible for the timely filing of such SCHEDULE 13G and any amendments thereto, and for the completeness and accuracy of the information concerning such person contained therein; but none of them is responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate. Dated: April 24, 2026 Great Point Partners, LLC By: /s/ Dr. Jeffrey R. Jay, M.D. Dr. Jeffrey R. Jay, M.D., as Senior Managing Member Dr. Jeffrey R. Jay, M.D. By: /s/ Dr. Jeffrey R. Jay, M.D. Dr. Jeffrey R. Jay, M.D. Ms. Lillian Nordahl By: /s/ Ms. Lillian Nordahl Ms. Lillian Nordahl Great Point Partners, LLC /s/ Dr. Jeffrey R. Jay, M.D 04/24/2026 Dr. Jeffrey R. Jay, M.D. /s/ Dr. Jeffrey R. Jay, M.D 04/24/2026 Ms. Lillian Nordahl /s/ Ms. Lillian Nordahl 04/24/2026