On November 24, 2025 Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the "Company", 6990.HK) reported that the Independent Data Monitoring Committee (IDMC) concluded that the Phase III clinical study (OptiTROP-Lung05) of the company’s TROP2 ADC sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870), in combination with MSD’s anti-PD-1 therapy KEYTRUDA[1] (pembrolizumab), as a first-line treatment for PD-L1-positive advanced non-small cell lung cancer (NSCLC), has demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS), the study’s primary endpoint. A positive trend in overall survival was also observed. This is the first Phase III clinical trial of ADC combined with immune checkpoint inhibitor to achieve its primary endpoint in the first-line treatment of NSCLC.
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OptiTROP-Lung05 is a randomized, open-label, multicenter Phase III clinical study evaluating the efficacy and safety profile of sac-TMT in combination with pembrolizumab versus pembrolizumab monotherapy as first-line treatment of patients with PD-L1-positive locally advanced or metastatic NSCLC with PD-L1 TPS ≥ 1%. At a pre-specified interim analysis, the sac-TMT combination therapy demonstrated a statistically significant and clinically meaningful improvement in PFS. Based on the results from the interim analysis, the Company plans to communicate with the Center for Drug Evaluation (CDE) of the National Medical Products Administration of China regarding the submission of a supplemental new drug application (sNDA) of sac-TMT.
Sac-TMT is already approved in China for the treatment of EGFR-mutant NSCLC in the second-line and later settings and has achieved dual benefits in PFS and overall survival (OS) in the EGFR-TKI-resistant lung cancer population, making it the first ADC to show statistically significant and clinically meaningful improvements in both PFS and OS compared to platinum doublet chemotherapy. These research findings have been published in internationally renowned journals, The New England Journal of Medicine and The BMJ.
Sac-TMT is currently being evaluated in ten registrational studies in lung cancer, including five registrational studies in China and five global multicenter Phase III studies.
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, 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 (which includes Mainland China, Hong Kong, Macao and Taiwan).
To date, three 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 and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the first TROP2 ADC drug approved for marketing in lung cancer globally. In addition, the sNDA for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA), and was included in the priority review and approval process.
As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 15 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.
(Press release, Kelun, NOV 24, 2025, View Source [SID1234660921])