SCHEDULE 13D/A 0001545806 XXXXXXXX LIVE 6 Ordinary Shares, $0.0001 par value 12/30/2024 false 0001962738 G1933S101 CASI Pharmaceuticals, Inc.

1701-1702, CHINA CENTRAL OFFICE TOWER 1, NO. 81 JIANGUO ROAD, CHAOYANG DISTRICT, BEIJING F4 100025

Chi Sing Ho 852-3903 1333 IDG Capital Management (HK) Company Ltd 99 Queen's Road, Central Hong Kong K3 00000 0001508829 IDG-Accel China Growth Fund III L.P. WC E9 855222 60628 855222 60628 915850 N 5.9 PN The value in lines 7 and 9 represents 855,222 ordinary shares of the Issuer held by the Reporting Person. The value in lines 8 and 10 represents 60,628 ordinary shares of the Issuer held by IDG-Accel China III Investors L.P. ("IDG-Accel Investors"). Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. 0001550193 IDG-Accel China III Investors L.P. WC E9 60628 855222 60628 855222 915850 N 5.9 PN The value in lines 7 and 9 represents 60,628 ordinary shares of the Issuer held by the Reporting Person. The value in lines 8 and 10 represents 855,222 ordinary shares of the Issuer held by IDG-Accel China Growth Fund III L.P. ("IDG-Accel Growth"). Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. 0001550192 IDG-Accel China Growth Fund III Associates L.P. AF E9 855222 60628 855222 60628 915850 N 5.9 PN The value in lines 7 and 9 represents 855,222 ordinary shares of the Issuer held by IDG-Accel Growth. The Reporting Person is the sole general partner of IDG-Accel Growth. By virtue of this affiliation, the Reporting Person may be deemed to have sole voting and dispositive power with respect to all these securities. The value in lines 8 and 10 represents 60,628 ordinary shares of the Issuer held by IDG-Accel Investors. The Reporting Person has the same general partner, IDG-Accel China Growth Fund GP III Associates Ltd. as IDG-Accel Investors. By virtue of this affiliation, the Reporting Person may be deemed to be under common control with IDG-Accel Investors and thus share voting and dispositive power with respect to these shares. Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. 0001564281 IDG-Accel China Growth Fund GP III Associates Ltd. AF E9 915850 0 915850 0 915850 N 5.9 CO The value in lines 7 and 9 represents (i) 855,222 ordinary shares of the Issuer held by IDG-Accel Growth; and (ii) 60,628 ordinary shares of the Issuer held by IDG-Accel Investors. The Reporting Person is the ultimate general partner of both IDG-Accel Growth and IDG-Accel Investors. By virtue of this affiliation, the Reporting Person may be deemed to have voting and dispositive power with respect to all these shares. Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. 0001545806 Ho Chi Sing AF Z4 0 915850 0 915850 915850 N 5.9 IN The value in lines 8 and 10 represents (i) 855,222 ordinary shares of the Issuer held by IDG-Accel Growth; and (ii) 60,628 ordinary shares of the Issuer held by IDG-Accel Investors. The Reporting Person and Quan Zhou are directors and shareholders of IDG-Accel China Growth Fund GP III Associates Ltd., the ultimate general partner of IDG-Accel Growth and IDG-Accel Investors, thus may be deemed to share voting and dispositive power with respect to all these shares. Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. 0001491503 Quan Zhou AF X1 76788 915850 76788 915850 992638 N 6.4 IN The value in lines 7 and 9 represents 76,788 ordinary shares of the Issuer issuable upon exercise of certain options issued by the Issuer to Quan Zhou. The value in lines 8 and 10 represents (i) 855,222 ordinary shares of the Issuer held by IDG-Accel Growth; and (ii) 60,628 ordinary shares of the Issuer held by IDG-Accel Investors. The Reporting Person and Chi Sing Ho are directors and shareholders of IDG-Accel China Growth Fund GP III Associates Ltd., the ultimate general partner of IDG-Accel Growth and IDG-Accel Investors, thus may be deemed to share voting and dispositive power with respect to all these shares. Percent of Class Represented by Amount in Row (11) is based on 15,492,581 ordinary shares of the Issuer outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the Securities and Exchange Commission on December 20, 2024. Ordinary Shares, $0.0001 par value CASI Pharmaceuticals, Inc. 1701-1702, CHINA CENTRAL OFFICE TOWER 1, NO. 81 JIANGUO ROAD, CHAOYANG DISTRICT, BEIJING F4 100025 This Amendment No. 6 amends the Statement on Schedule 13D dated January 30, 2012 as amended by Amendment No. 1 dated February 2, 2012, Amendment No. 2 dated June 11, 2012, Amendment No. 3 dated March 6, 2013, Amendment No. 4 dated March 20, 2018 and Amendment No.5 dated February 21, 2023 (as so amended, the "Original Schedule 13D") and is being filed to reflect changes in the number and percentage of Ordinary Shares (as defined below) beneficially owned by the Reporting Persons due to (a) the expiration of certain warrants issued by the Issuer to IDG-Accel Growth and IDG-Accel Investors on March 19, 2018, (b) increase in the amount of total issued and outstanding Ordinary Shares over time, and (c) increase in the amount of Ordinary Shares beneficially owned by the Reporting Persons due to purchases in open market from time to time. Except as amended and supplemented herein, the information set forth in the Original Schedule 13D remains unchanged. Capitalized terms used herein have meanings as assigned thereto in the Original Schedule 13D, unless defined herein. Item 1 of the Original Schedule 13D is hereby amended and restated in its entirety as follows: The class of equity securities to which this Statement on Schedule 13D relates is the ordinary shares, par value $0.0001 per share (the "Ordinary Share"), of CASI Pharmaceuticals, Inc., an exempted company with limited liability incorporated under the laws of the Cayman Islands (the "Issuer"). The principal executive offices of the Issuer are located at 1701-1702, China Central Office Tower 1, No. 81 Jianguo Road Chaoyang District, Beijing, 100025, People's Republic of China. In December 2024, in a series of open market purchases, IDG-Accel Growth purchased additional 57,869 Ordinary Shares in total with an aggregate purchase price of $180,972.10 (including commission fee), and IDG-Accel Investors purchased additional 4,102 Ordinary Shares in total with an aggregate purchase price of $12,723.89 (including commission fee). The source of funds for such purchases was the available capital of IDG-Accel Growth and IDG-Accel Investors, which may, at any given time, include margin loans made by brokerage firms or unsecured borrowings under a working capital credit line, each in the ordinary course of business. Item 5(a) of the Original Schedule 13D is hereby amended and restated in its entirety as follows: (a) Each of the Reporting Persons' current ownership in the Issuer and the Ordinary Shares is set forth on the cover pages to this Statement on Schedule 13D and is incorporated by reference herein. The ownership percentage appearing on such pages has been calculated based on a total of 15,492,581 Ordinary Shares outstanding as of December 18, 2024, as disclosed in the Issuer's registration statement on Form F-3 filed with the SEC on December 20, 2024. The Reporting Persons disclaim membership in any "group" with any person other than the Reporting Persons. The filing of this Statement on Schedule 13D by the Reporting Persons shall not be considered an admission that such Reporting Persons, for the purpose of Section 13(d) of the Exchange Act, are the beneficial owners of any of the Ordinary Shares covered in this Statement on Schedule 13D, and the Reporting Persons expressly disclaim such beneficial ownership. Item 5(b) of the Original Schedule 13D is hereby amended and restated in its entirety as follows: (b) The following table sets forth the beneficial ownership of Ordinary Shares for each of the Reporting Persons. Reporting Person Number of Percentage Sole Power Shared Sole Power to Shared Ordinary of to Power to Dispose/Direct Power Shares Ordinary Vote/Direct Vote/Direct Disposition to Beneficially Shares Vote Vote Dispose/ Owned Direct Disposition IDG-Accel Growth 915,850 5.9% 855,222 60,628 855,222 60,628 IDG-Accel Investors 915,850 5.9% 60,628 855,222 60,628 855,222 IDG-Accel Associates 915,850 5.9% 855,222 60,628 855,222 60,628 IDG-Accel GP 915,850 5.9% 915,850 0 915,850 0 Chi Sing Ho 915,850 5.9% 0 915,850 0 915,850 Quan Zhou 992,638 6.4% 76,788 915,850 76,788 915,850 Item 5(c) of the Original Schedule 13D is hereby amended and restated in its entirety as follows: (c) The following describes all transactions in the Issuer's Ordinary Shares that were effected by IDG-Accel Growth and IDG-Accel Investors respectively during the past 60 days by the Reporting Person: Transaction Date Nature of Price Per Quantity of Where/How Transaction Ordinary Ordinary Effected Share Shares IDG-Accel Growth 12/3/2024 Purchase 3.9422 4,669 Open Market 12/6/2024 Purchase 3.1250 1,964 Open Market 12/10/2024 Purchase 3.5219 4,669 Open Market 12/12/2024 Purchase 3.1501 4,669 Open Market 12/13/2024 Purchase 3.2317 4,669 Open Market 12/16/2024 Purchase 3.2018 4,669 Open Market 12/17/2024 Purchase 3.0511 4,669 Open Market 12/18/2024 Purchase 2.9460 4,669 Open Market 12/19/2024 Purchase 2.7796 4,669 Open Market 12/20/2024 Purchase 2.7359 4,669 Open Market 12/23/2024 Purchase 2.6219 4,359 Open Market 12/26/2024 Purchase 2.7700 187 Open Market 12/27/2024 Purchase 2.9793 4,669 Open Market 12/30/2024 Purchase 2.8977 4,669 Open Market IDG-Accel Investors 12/3/2024 Purchase 3.9422 331 Open Market 12/6/2024 Purchase 3.1250 139 Open Market 12/10/2024 Purchase 3.5219 331 Open Market 12/12/2024 Purchase 3.1501 331 Open Market 12/13/2024 Purchase 3.2317 331 Open Market 12/16/2024 Purchase 3.2018 331 Open Market 12/17/2024 Purchase 3.0511 331 Open Market 12/18/2024 Purchase 2.9460 331 Open Market 12/19/2024 Purchase 2.7796 331 Open Market 12/20/2024 Purchase 2.7359 331 Open Market 12/23/2024 Purchase 2.6219 309 Open Market 12/26/2024 Purchase 2.7700 13 Open Market 12/27/2024 Purchase 2.9793 331 Open Market 12/30/2024 Purchase 2.8977 331 Open Market IDG-Accel China Growth Fund III L.P. /s/ Chi Sing Ho on behalf of IDG-Accel China Growth Fund GP III Associates Ltd., ultimate General Partner of IDG-Accel China Growth Fund III L.P. 01/27/2025 IDG-Accel China III Investors L.P. /s/ Chi Sing Ho on behalf of IDG-Accel China Growth Fund GP III Associates Ltd., General Partner of IDG-Accel China III Investors L.P. 01/27/2025 IDG-Accel China Growth Fund III Associates L.P. /s/ Chi Sing Ho on behalf of IDG-Accel China Growth Fund GP III Associates Ltd., General Partner of IDG-Accel China Growth Fund III Associates L.P. 01/27/2025 IDG-Accel China Growth Fund GP III Associates Ltd. /s/ Chi Sing Ho 01/27/2025 Ho Chi Sing /s/ Ho Chi Sing 01/27/2025 Quan Zhou /s/ Quan Zhou 01/27/2025