科伦博泰sac-TMT一线晚期TNBC新适应症上市申请获NMPA受理

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# Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. 四 川 科 倫 博 泰 生 物 醫 藥 股 份 有 限 公 司

(A joint stock company incorporated in the People’s Republic of China with limited liability)

(Stock Code: 6990)

## VOLUNTARY ANNOUNCEMENT NEW INDICATION APPLICATION FOR CORE PRODUCT TROP2 ADC SACITUZUMAB TIRUMOTECAN (sac-TMT) ACCEPTED BY THE NATIONAL MEDICAL PRODUCTS ADMINISTRATION

The board (the “Board”) of directors (“Directors”) of Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) is pleased to announce that a new indication application of its TROP2 ADC sacituzumab tirumotecan (sac-TMT, also known as SKB264/ MK-2870) (佳泰萊®) has been accepted for review by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China, for the first-line treatment of patients with recurrent or metastatic triple-negative breast cancer (TNBC) who have a programmed death ligand 1 (PD-L1) combined positive score (CPS) <10, or have recurred after prior programmed cell death protein 1 (PD-1)/PD-L1 inhibitor therapy in the early stage. This marks the sixth indication application accepted by the NMPA for sac-TMT.

The acceptance for review is based on the positive results from the randomized, open-label, multicenter Phase 3 registrational OptiTROP-Breast03 study evaluating the efficacy and safety of sac-TMT versus investigator’s choice of chemotherapy in patients with unresectable recurrent or metastatic TNBC who have not received prior systemic therapy for advanced disease. The enrolled population included patients with PD-L1 CPS <10, as well as those who have recurred after prior PD-1/PD-L1 inhibitor therapy in the early stage. The study demonstrated that sac-TMT achieved statistically significant and clinically meaningful improvements in key efficacy profile compared with investigator’s choice of chemotherapy, showing a clear clinical benefit.

Previously, sac-TMT was granted Breakthrough Therapy Designation (BTD) by the NMPA for the first-line treatment of unresectable locally advanced, recurrent or metastatic PD-L1negative TNBC. This new indication application has also been included in the priority review and approval process, becoming the sixth application for sac-TMT to enter this process. Inclusion in this process is expected to further expedite the review and approval, allowing this innovative treatment to benefit patients sooner.

### About sac-TMT(佳泰萊®)

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as non-small cell lung cancer (NSCLC), breast cancer (BC), gastric cancer (GC), gynecological tumors and genitourinary tumors, among others. Sac-TMT is developed with a unique, bifunctional linker that maximizes payload delivery to tumor cells both through its irreversible connection with the anti-TROP2 monoclonal antibody sacituzumab and its pH-sensitive cleavage from a belotecan-derivative topoisomerase I inhibitor payload in the lysosome, with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc, Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macao and Taiwan).

To date, four indications for sac-TMT have been approved and marketed in China for: 1) unresectable locally advanced or metastatic TNBC who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting); 2) epidermal growth factor receptor (EGFR) mutant-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-tyrosine kinase inhibitor (TKI) therapy and platinum-based chemotherapy; 3) EGFR mutant-positive locally advanced or metastatic nonsquamous NSCLC who progressed after treatment with EGFR-TKI therapy; 4) unresectable or metastatic hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) (Immunohistochemistry (IHC) 0, IHC 1+ or IHC 2+/In Situ Hybridization (ISH)-) BC who have received prior endocrine therapy and at least one line of chemotherapy in advanced setting. The first two indications above have been included in China’s National

Reimbursement Drug List (NRDL). This inclusion is expected to bring clinically meaningful benefits to a greater number of patients with BC and NSCLC. Additionally, sac-TMT has been granted six BTDs by the NMPA.

Sac-TMT is the world’s first TROP2 ADC drug approved for marketing in lung cancer. Two new indication applications have been accepted for review by the NMPA and have been included in the priority review and approval process:1) sac-TMT in combination with pembrolizumab (KEYTRUDA®1) as first-line treatment for locally advanced or metastatic NSCLC who have PD-L1 tumor proportion score (TPS)≥1% and are EGFR-negative and anaplastic lymphoma kinase (ALK)-negative; and 2) sac-TMT as first-line treatment for patients with recurrent or metastatic TNBC who have a PD-L1 CPS<10 or have recurred after prior PD-1/PD-L1 inhibitor therapy in the early stage.

As of today, Kelun-Biotech has initiated 9 registrational clinical studies in China. MSD has initiated 17 ongoing global Phase 3 clinical studies of sac-TMT as a monotherapy or in combination with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

RISK WARNING

SACITUZUMAB TIRUMOTECAN (SAC-TMT) FOR THE TREATMENT OF OTHER INDICATIONS NOT YET APPROVED, MAY NOT ULTIMATELY BE SUCCESSFULLY DEVELOPED AND COMMERCIALIZED. THE COMPANY’S SHAREHOLDERS AND POTENTIAL INVESTORS ARE REMINDED TO EXERCISE CAUTION WHEN DEALING IN THE SECURITIES OF THE COMPANY.

By order of the Board Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. LIU Gexin Chairman of the Board and Non-executive Director

Hong Kong, July 30, 2026

As at the date of this announcement, the Board comprises Mr. LIU Gexin as the chairman of the Board and non-executive Director, Dr. GE Junyou as executive Director, Mr. LIU Sichuan, Mr. LAI Degui, Mr. FENG Hao, Ms. LIAO Yihong and Mr. ZENG Xuebo as non-executive Directors, and Dr. ZHENG Qiang, Dr. TU Wenwei, Dr. JIN Jinping and Dr. LI Yuedong as independent non-executive Directors.

1 KEYTRUDA® (pembrolizumab) is a registered trademark of Merck Sharp & Dohme LLC (MSD), a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.