CHENGDU, China, Sept. 23, 2025 -- The 2025 European Society for Medical Oncology (ESMO) Congress will take place in Berlin, Germany, from October 17 to 21. Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech", HKEX: 6990) will present results from multiple clinical studies at the congress, including data from its TROP2 ADC sacituzumab tirumotecan (sac-TMT), HER2 ADC A166 (trastuzumab botidotin), and CLDN18.2 ADC SKB315. Among these, two Phase III clinical studies of sac-TMT were selected for the Latest Breakthrough Abstracts (LBA) and presented as oral reports, including one featured in the Presidential Symposium; one Phase III clinical study of A166 was selected for LBA and presented as oral report.

Abstract titles of these studies have been published on the official website of ESMO. The study results to be presented include:

Title: Sacituzumab tirumotecan (sac-TMT) vs platinum-based chemotherapy in EGFR-mutated (EGFRm) non-small cell lung cancer (NSCLC) following progression on EGFR-TKIs: results from the randomized, multi-center phase 3 OptiTROP-Lung04 study
Presentation Type: Presidential Symposium
Presentation #: LBA5
Date and Lecture Time: October 19, 4：52 PM to 5:04 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) vs investigator's choice of chemotherapy (ICC) in previously treated locally advanced or metastatic hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer (BC): results from the randomized, multi-center phase 3 OptiTROP-Breast02 study
Presentation Type: Proffered Paper
presentation #: LBA23
Date and Lecture Time: October 18, 10:45 AM to 10:55 AM local time

Title: Trastuzumab botidotin vs trastuzumab emtansine (T-DM1) in HER2-positive unresectable or metastatic breast cancer: results from a randomized phase 3 study
Presentation Type: Proffered Paper
presentation #: LBA24
Date and Lecture Time: October 18, 10:55 AM to 11:05AM local time

Title: SKB315, a novel Claudin 18.2 (CLDN18.2) antibody-drug conjugate (ADC), in patients (pts) with advanced solid tumors including gastric/ gastroesophageal junction cancer (GC/GEJC): a phase 1 study
Presentation Type: Poster
Presentation #: 2139P
Date and Session Time: October 19, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) in Participants (pts) with Previously Treated, Advanced KRAS-Mutant NSCLC: Results from Cohort 5d of the SKB264-II-08 Study
Presentation Type: Poster
Presentation #: 1945P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) + pembrolizumab^[1] (pembro) for treatment-naïve advanced PD-L1 positive NSCLC: results from the Phase 2 MK-2870-003/SKB264-II-04 study
Presentation Type: Poster
Presentation #: 1949P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) + Pembrolizumab in Metastatic Castration-Resistant Prostate Cancer (mCRPC): Results from Phase 2 MK-2870-002/SKB264-II-06 Study
Presentation Type: Poster
Presentation #: 2421P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (Sac-TMT) Monotherapy in Advanced/Metastatic Endometrial Carcinoma (EC): Results from a Phase 1/2 Study (MK-2870-001/KL264-01)
Presentation Type: Poster
Presentation #: 1111P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Efficacy and Safety of sacituzumab tirumotecan (Sac-TMT) Monotherapy in Advanced/Metastatic Cervical Cancer: Results from a Phase 1/2 Study (MK-2870-001/KL264-01)
Presentation Type: Poster
Presentation #: 1168P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

About sac-TMT

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 NSCLC, BC, gastric cancer (GC), gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor 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 (includes Mainland China, Hong Kong, Macau, and Taiwan).

To date, 2 indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy. In addition, two new indication applications for sac-TMT for the treatment of adult patients with EGFR-mutant locally advanced or metastatic NSCLC who progressed after treatment with EGFR-TKI therapy and with unresectable locally advanced, metastatic hormone receptor positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting were accepted by the Center for Drug Evaluation of NMPA, and were included in the priority review and approval process. As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 14 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Trastuzumab Botidotin (A166)

Trastuzumab botidotin is a differentiated HER2 ADC in new drug application (NDA) registration stage to treat advanced HER2+ solid tumors. As an innovative HER2 ADC developed by the Company, it conjugates a novel, MMAF derivative (a highly cytotoxic tubulin inhibitor, Duo-5) via a stable, enzyme-cleavable linker to a HER2 monoclonal antibody with a DAR of 2. Trastuzumab botidotin specifically binds to HER2 on the surface of tumor cells and is internalized by tumor cells, releasing the toxin molecule Duo-5 inside the cell. Duo-5 induces tumor cell cycle arrest in the G2/M phase, leading to tumor cell apoptosis. After targeting HER2, trastuzumab botidotin can also inhibit the HER2 signaling pathway; it has antibody-dependent cell-mediated cytotoxicity (ADCC) activity.

Based on the results of a randomized, controlled, open-label Phase III study, the New Drug Application (NDA) for trastuzumab botidotin was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) in January 2025 for the treatment of adult patients with HER2+ unresectable or metastatic BC who have received at least one prior anti-HER2 therapy was accepted by the CDE of the NMPA. At a pre-specified interim analysis, trastuzumab botidotin monotherapy demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of progression-free survival (PFS) as assessed by the Blinded Independent Central Review (BICR) compared with T-DM1.

Currently, Kelun-Biotech has initiated an open, multi-center Phase II clinical study of trastuzumab botidotin in the treatment of HER2+ unresectable or metastatic BC that previously received a topoisomerase inhibitor ADC.

About SKB315

SKB315 is a novel CLDN18.2 ADC targeting advanced solid tumors configured with a proprietary, in-house developed humanized CLDN18.2 mAb and a differentiated payload-linker design. Currently, Kelun-Biotech has initiated the exploration in combination with immunotherapy for gastric/gastroesophageal junction cancer (GC/GEJC) while advancing monotherapy studies for tumors expressing CLDN18.2, such as GC/GEJC and pancreatic cancer.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 3 projects have been approved for marketing, 2 projects are in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 1 ADC project approved for marketing,1 ADC project in NDA stage and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.