Sacituzumab Tirumotecan (sac-TMT) in Combination with Pembrolizumab for First-Line Treatment of PD-L1-Positive NSCLC Published in The Lancet

CHENGDU, China, May 31, 2026 /PRNewswire/ — Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”, 6990.HK) announced today that the results of the Phase III clinical study OptiTROP-Lung05, evaluating the company’s trophoblast cell-surface antigen 2 (TROP2)-directed antibody drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870)(佳泰莱^®) in combination with pembrolizumab (KEYTRUDA^®[1], MSD’s anti-programmed cell death protein 1 (PD-1) antibody) as first-line treatment for Programmed Death-Ligand 1 (PD-L1) Tumor Proportion Score (TPS)≥1% non-small cell lung cancer (NSCLC), have been published in the prestigious international medical journal The Lancet (IF=88.5)^[2]. The co-senior authors are: Professor Caicun Zhou from Shanghai East Hospital, Tongji University; and Dr. Junyou Ge, Director of the National Engineering Research Centre of Targeted Biologics. The co‑first authors are: Professor Anwen Xiong from Shanghai East Hospital, Tongji University; Professor Wenxiu Yao from Sichuan Cancer Hospital; Professor Wei Zheng from Shengjing Hospital, China Medical University; Professor Yan Yu from Harbin Medical University Cancer Hospital; Professor Peng Chen from Tianjin Medical University Cancer Institute and Hospital; Professor Hua Zhong from Shanghai Chest Hospital; and Dr. Junyou Ge, Director of the National Engineering Research Centre of Targeted Biologics. The study findings were also selected for an oral presentation at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract #8506, Lung Cancer – Metastatic Non-Small Cell).

OptiTROP-Lung05 is a randomized, open-label, multicenter Phase III clinical study designed to evaluate the efficacy and safety of sac-TMT in combination with pembrolizumab versus pembrolizumab alone as first-line treatment for patients with locally advanced or metastatic PD-L1 TPS≥1% NSCLC.

The interim analysis results show that compared with pembrolizumab monotherapy, the combination of sac-TMT and pembrolizumab significantly prolongs progression-free survival (PFS) and reduces the risk of disease progression or death, with a hazard ratio (HR) of 0.35. Consistent PFS benefits were observed across all prespecified subgroups, including by PD-L1 expression level and histological type, with PFS HRs of 0.47 and 0.28 for the PD-L1 TPS ≥50% and 1–49% subgroups, respectively, and PFS HRs of 0.28 and 0.44 for the non-squamous and squamous subgroups, respectively. A positive trend in overall survival (OS) was also observed, with an HR of 0.55. Furthermore, the overall safety profile of sac-TMT in combination with pembrolizumab was manageable, consistent with the established safety profiles of sac-TMT alone or pembrolizumab alone, and no new safety signals identified.

This is the first Phase III trial of an ADC combined with an immune checkpoint inhibitor to meet its primary endpoint in the first line treatment of NSCLC, and for the first time demonstrate that “ADC+IO” combination of sac-TMT plus pembrolizumab has the potential to achieve survival benefit as first‑line therapy for NSCLC. The publication of these findings in The Lancet further signifies that the clinical and academic value of this combination therapy has received internationally recognized validation.

About sac-TMT(佳泰莱^®)

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, 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 triple‑negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting); 2) EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC following progression on epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy and platinum-based chemotherapy; 3) epidermal growth factor receptor (EGFR) mutant-positive locally advanced or metastatic non-squamous 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 Breakthrough Therapy Designations (BTDs) by the National Medical Products Administration (NMPA).

Sac-TMT is the world’s first TROP2 ADC drug approved for marketing in lung cancer. A new indication application for sac-TMT in combination with pembrolizumab (KEYTRUDA^®) as first‑line treatment for locally advanced or metastatic NSCLC who have PD-L1 TPS≥1% and are EGFR-negative and anaplastic lymphoma kinase (ALK)-negative has been accepted for review by the NMPA, and has entered the priority review and approval process. As of today, Kelun-Biotech has initiated 9 registrational clinical studies in China. MSD is evaluating 17 ongoing global Phase III 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.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical, which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. Kelun-Biotech focuses on major disease areas such as solid tumors, autoimmune, 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. Kelun-Biotech is committed to becoming a leading global enterprise in the field of innovative drugs. At present, Kelun-Biotech has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, 1 project is in the new drug application (NDA) stage and more than 10 projects are in the clinical stage. Kelun-Biotech has established one of the world’s leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC projects approved for marketing, and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://en.kelun-biotech.com/.