VOLUNTARY ANNOUNCEMENT - NEW DRUG APPLICATION FOR ANBENITAMAB (KN026) AND DOCETAXEL FOR INJECTION (ALBUMIN-BOUND) (HB1801) FOR THE FIRST-LINE TREATMENT OF ADVANCED BREAST CANCER ACCEPTED BY THE NMPA

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CSPC PHARMACEUTICAL GROUP LIMITED (Incorporated in Hong Kong with limited liability) (Stock Code: 1093) ʮ ̡ VOLUNTARY ANNOUNCEMENT NEW DRUG APPLICATION FOR ANBENITAMAB (KN026) AND DOCETAXEL FOR INJECTION (ALBUMIN-BOUND) (HB1801) FOR THE FIRST-LINE TRE ATMENT OF ADVANCED BREAST CANCER ACCEPTED BY THE NMPA The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that the new drug application for Anbenitamab ( ‘‘KN026 ’’), co-developed by Shanghai JMT-BIO Technology Co., Ltd., a subsidiary of the Company, and Jiangsu Alphamab Oncology Co., Ltd., in com bination with the Group ’s self- developed Docetaxel for Injection (Albumin-bound) ( ‘‘HB1801 ’’) for the first-line treatment of advanced breast cancer, has been accepted by the National Me dical Products Administration (the ‘‘NMPA ’’) of the People ’s Republic of China and has been included in the priority revi ew and approval procedure. The indication for this new drug application is A nbenitamab in combination with Docetaxel (Albumin-bound) for the first-line treatment of unresecta ble or metastatic human epidermal growth factor receptor 2 ( ‘‘HER2 ’’)-positive breast cancer in adults. Previously, the combin ation therapy of KN026 and HB1801 for this indication was granted Breakthrou gh Therapy Designation by the NMPA. Anbenitamab is a HER2 bispecific antibody that can simultan eously bind two non-overlapping epitopes of HER2, blocking HER2 signalling, enhancing HER2 internal isation, downregulating HER2 expression, and retaining the antibody-dependent cellula r cytotoxicity (ADCC) effect. This product has already been approved for marketing in China. HB1801 is one of the representative drugs independently dev eloped by the Group ’s nanomedicine technology platform. HB1801 encapsulates docetaxel in hum an albumin. It has the following advantages over traditional docetaxel injection: (1) Safe ty: It causes no allergic reactions, does not require steroid premedication, and allows for high-concen tration and rapid administration, effectively improving safety and patient compliance; (2) Efficacy: Pre clinical and clinical studies have shown that it exhibits excellent antitumor activity, and it can be admi nistered at a higher dose clinically, further improving efficacy. – 1 – This New Drug Application is primarily based on a pivotal Pha se III clinical trial (Study No.: KN026- 003/Healer). The study results indicate that the combinati on therapy of KN026 and HB1801 for the first-line treatment of advanced HER2-positive breast can cer demonstrated significantly superior progression-free survival ( ‘‘PFS’’) compared to the current standard of care (trastuzumab in combination with pertuzumab and docetaxel), with differen ces that are both statistically significant and clinically meaningful, and the overall safety profile rema ining favourable. Detailed clinical data from this study will be presented at an upcoming international ac ademic conference. In China, approximately 20% of breast cancer patients are al ready at an advanced stage upon initial diagnosis, and approximately 10% of patients with HER2-pos itive early breast cancer experience disease recurrence within 3 years after radical surgery. Cu rrently, trastuzumab in combination with pertuzumab and docetaxel remains the preferred first-line treatment for HER2-positive advanced breast cancer both domestically and overseas. Although this treat ment regimen has significantly prolonged the PFS of these patients, approximately 50% of patients still e xperience disease progression within 2 years, representing an urgent unmet clinical need. The Heal er study is the world ’s first Phase III clinical trial of a HER2 bispecific antibody in combination with HB1801 for HER2-positive advanced breast cancer to demonstrate superior efficacy over the ‘‘trastuzumab and pertuzumab plus docetaxel ’’ regimen in a head-to-head comparison. The success of this st udy marks a historic breakthrough for the aforementioned novel combination therapy in the first-lin e treatment of HER2-positive advanced breast cancer. It is expected to provide a new treatment option with superior efficacy, a favourable safety profile, and more convenient administration for domestic p atients with HER2-positive advanced breast cancer. Currently, the combination therapy of KN026 and HB1801 has c ompleted the comprehensive clinical layout across the entire disease course for HER2-positive b reast cancer, encompassing neoadjuvant, adjuvant, and first-line advanced settings. Notably, the N ew Drug Application for this combination regimen for the neoadjuvant treatment of HER2-positive ear ly or locally advanced breast cancer in adults was accepted by the NMPA on 4 August 2026 and included i n the priority review and approval procedure. By Order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 18 August 2026 As at the date of this announcement, the Board comprises Mr. C AI Dong Chen, Dr. CAI Lei, Mr. WEI Qingjie, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Dr. LI Chunlei , Dr. YAO Bing, Mr. CAI Xin, Mr. CHEN Weiping, Mr. QU Zhiyong and Mr. ZHANG Yiwei as Executive Directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, M r. LAW Cheuk Kin Stephen and Ms. LI Quan as Independent Non-executive Directors. – 2 –

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