石药集团SYS 6090结直肠癌Ib/II期临床试验在中国首家中心启动

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.

# CSPC PHARMACEUTICAL GROUP LIMITED

## 石 藥 集 團 有 限 公 司

(Incorporated in Hong Kong with limited liability)

(Stock Code: 1093)

VOLUNTARY ANNOUNCEMENT

PHASE IB/II CLINICAL TRIAL OF SYS 6090 INJECTION FOR THE TREATMENT OF COLORECTAL CANCER OFFICIALLY INITIATED AT THE FIRST CENTRE IN CHINA

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 Phase Ib/II clinical trial (SYS 6090-008) of the combination therapy of SYS 6090 Injection (the ‘‘Product’’) developed by the Group for the treatment of colorectal cancer has been officially initiated at the first research centre in China.

The Product, with a registration classification as a Class 1 therapeutic biological product, is a recombinant fully human anti-programmed cell death receptor 1 (‘‘PD-1’’) and interleukin-15 (‘‘IL-15’’) fusion protein. It targets PD-1-positive tumour-infiltrating immune cells through its left arm, to block the immunosuppressive function caused by the interaction between PD-1 and programmed death ligand 1 (PD-L1); meanwhile, it binds to the IL-15 receptor through its right arm to activate its downstream signalling pathways, further promoting the activation and proliferation of relevant immune cells. Pre-clinical study results showed that the Product significantly inhibited tumour growth with favourable safety and tolerability, and demonstrate superior pharmacodynamic activity compared to other PD-1 monoclonal antibody drugs and IL-15 agents.

Previously, the Group received the Notice of Approval for Clinical Trial of Drug issued by the National Medical Products Administration of the People’s Republic of China for the Product in March 2026, and initiated the SYS 6090-008 clinical trial following the approval. The approved clinical trial is an openlabel, multi-centre Phase Ib/II clinical trial aimed at evaluating the safety, tolerability and efficacy of the combination therapy of the Product in participants with colorectal cancer.

Based on the results of this study, the Group will subsequently continue to advance the Phase III confirmatory clinical trial of the combination therapy of the Product in participants with colorectal cancer, to further verify the clinical value of the combination therapy of the Product. Currently, the recruitment and screening of participants for the SYS 6090-008 study are actively underway.

By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 3 August 2026

As at the date of this announcement, the Board comprises Mr. CAI 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, Mr. LAW Cheuk Kin Stephen and Ms. LI Quan as Independent Non-executive Directors.