Sichuan Kelun Pharmaceutical Co., Ltd.’s announcement that the subsidiary’s core product TROP2 ADC sacituzumab tirumotecan (sac-TMT)’s marketing application for new indications has been accepted by the National Medical Products Administration

Securities code: 002422 Securities abbreviation: Kelun Pharmaceutical Announcement number: 2026-059

The company and all members of the board of directors guarantee that the information disclosed is true, accurate and complete, and that there are no false records, misleading statements or major omissions.

Sichuan Kelun Pharmaceutical Co., Ltd. (the “Company”) recently learned that the Center for Drug Evaluation (CDE) of China’s National Medical Products Administration (NMPA) has accepted a new indication application for sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870; Jiatelai®), the human trophoblast cell-surface antigen 2 (TROP2)-targeting antibody–drug conjugate (ADC) of its controlled subsidiary Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (“Kelun-Biotech”). The application is for first-line treatment of recurrent or metastatic triple-negative breast cancer (TNBC) with a programmed death-ligand 1 (PD-L1) combined positive score (CPS) <10, or after prior programmed cell death protein 1 (PD-1)/PD-L1 inhibitor treatment in the early-stage setting. This is sac-TMT’s sixth indication application accepted by the NMPA. The key information is as follows:

1. Basic information This acceptance is based on the positive results of the randomized, open, multi-center Phase 3 registration OptiTROP-Breast03 study. This study aims to evaluate the efficacy and safety of sacituzumab tirumotecan (sac-TMT) compared with investigator's choice of chemotherapy in patients with unresectable recurrent or metastatic TNBC who have not received systemic therapy in the late stage. The enrolled population includes patients with PD-L1 CPS <10 and patients who have previously relapsed after receiving PD-1/PD-L1 inhibitor therapy in the early stage. The results of the study showed that compared with the chemotherapy chosen by the investigators, sacituzumab tirumotecan (sac-TMT) achieved statistically significant and clinically meaningful improvements in key efficacy indicators, demonstrating clear clinical benefit.

Previously, sacituzumab tirumotecan (sac-TMT) has been granted Breakthrough Therapy Designation (BTD) by the NMPA for the first-line treatment of unresectable locally advanced, recurrent or metastatic PD-L1-negative TNBC. This new indication marketing application has also been included in the priority review and approval process, becoming the sixth marketing application for sacituzumab tirumotecan (sac-TMT) included in this process. Including the priority review and approval process is expected to further speed up the review and marketing process, allowing this innovative treatment option to benefit patients earlier.

2. About sacituzumab tirumotecan (sac-TMT) (Jiatelai®) As the core product of Kelun-Biotech, sacituzumab tirumotecan (sac-TMT) is a new TROP2 ADC with independent intellectual property rights by Kelun-Biotech, targeting advanced solid tumors such as non-small cell lung cancer (NSCLC), breast cancer (BC), gastric cancer (GC), gynecological tumors and genitourinary system tumors. Sacituzumab tirumotecan (sac-TMT) is developed using a unique bifunctional linker. On the one hand, this linker forms an irreversible binding to the anti-TROP2 monoclonal antibody sacituzumab, and on the other hand, it can be pH-sensitively cleaved from the belotecan derivative topoisomerase I inhibitor payload in lysosomes, thereby maximizing the delivery of the payload to tumor cells with a drug-to-antibody ratio (DAR) of 7.4. Sacituzumab tirumotecan (sac-TMT) specifically recognizes TROP2 on the surface of tumor cells through a recombinant anti-TROP2 humanized monoclonal antibody, which is then endocytosed by tumor cells and releases the payload KL610023 within the cells. As a topoisomerase I inhibitor, KL610023 can induce DNA damage in tumor cells, leading to cell cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is cell membrane permeable, it can achieve the bystander effect, killing neighboring tumor cells.

In May 2022, Kelun-Biotech granted Merck (a trading name of Merck & Co., Rowe, New Jersey, USA) the exclusive rights to develop, use, manufacture and commercialize sacituzumab tirumotecan (sac-TMT) in all regions except Greater China (including mainland China, Hong Kong, Macau and Taiwan).

So far, 4 indications of sacituzumab tirumotecan (sac-TMT) have been approved for marketing in China, which are used for: 1. Unresectable locally advanced or metastatic TNBC that has received at least 2 previous systemic treatments (at least 1 of which is for advanced or metastatic stages); 2. EGFR that has progressed after treatment with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) and platinum-based chemotherapy. Gene mutation-positive locally advanced or metastatic non-squamous NSCLC; 3. EGFR gene mutation-positive locally advanced or metastatic non-squamous NSCLC that progresses after EGFR-TKI treatment; 4. Unresectable or metastatic hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) who have previously received endocrine therapy and received at least first-line chemotherapy in advanced disease stages (IHC 0, IHC 1+ or IHC 2+/in situ hybridization (ISH)-) BC; the first two indications have been included in the scope of medical insurance and will bring clinical benefits to more patients with breast cancer and non-small cell lung cancer. In addition, sacituzumab tirumotecan (sac-TMT) has been granted 6 BTDs by the NMPA.

Sacituzumab tirumotecan (sac-TMT) is the world’s first TROP2 ADC approved for a lung cancer indication. The NMPA has accepted applications for two additional indications: 1. In combination with pembrolizumab (Keytruda®¹) as first-line treatment of locally advanced or metastatic NSCLC with PD-L1 tumor proportion score (TPS) ≥1%, negative for EGFR mutations and anaplastic lymphoma kinase (ALK); 2. First-line treatment of recurrent or metastatic TNBC with PD-L1 CPS <10, or after prior PD-1/PD-L1 inhibitor treatment in the early-stage setting. Both applications have entered the priority review and approval process.

Currently, Kelun-Biotech has conducted 9 registered clinical studies in China. Merck has initiated 17 ongoing global Phase 3 clinical studies of sacituzumab tirumotecan (sac-TMT) as monotherapy or in combination with pembrolizumab or other anticancer drugs in various types of cancer (these studies are sponsored and led by Merck).

3. Risk warning: The research and development process of innovative drugs has a long cycle and many links, and there is a certain degree of uncertainty about whether it can be successfully developed and commercialized. Investors are advised to make prudent decisions and pay attention to preventing investment risks. The company will promptly fulfill its information disclosure obligations based on subsequent progress.

Announcement is hereby made.

Board of Directors of Sichuan Kelun Pharmaceutical Co., Ltd. July 31, 2026 1 Keytruda® (pembrolizumab) is a registered trademark of Merck Sharp & Dohme LLC (Merck & Co.), a subsidiary of Merck & Co., Rowe, New Jersey, USA