Nature Medicine Publishes Results of Phase II Study of Sacituzumab Tirumotecan Plus Tagitanlimab as First-Line Therapy for NSCLC

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CHENGDU, China, Aug. 19, 2025 /PRNewswire/ -- Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech", HKEX: 6990) announced that clinical data from a Phase II study evaluating novel TROP2 antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) in combination with PD-L1 monoclonal antibody (mAb) tagitanlimab for the first-line treatment of advanced or metastatic non-small cell lung cancer (NSCLC) have been published in Nature Medicine (Impact Factor: 58.7).

The publication highlighted initial findings from the Phase II OptiTROP-Lung01 study, evaluating the efficacy and safety results of sac-TMT in combination with tagitanlimab as a first-line treatment of advanced or metastatic NSCLC patients without actionable genomic alterations. The study was led by Prof. Zhang Li's team at the Center for Cancer Prevention and Control, Sun Yat-sen University, China. Patients in Cohort 1A received sac-TMT (5 mg/kg, Q3W) plus tagitanlimab (1200 mg, Q3W) in a three-week cycle, while patients in Cohort 1B were treated with sac-TMT (5 mg/kg, Q2W) plus tagitanlimab (900 mg, Q2W) in a four-week cycle. Patients received sac-TMT in combination with tagitanlimab in a non-randomized manner until disease progression or unacceptable toxicity. Median follow-ups for Cohort 1A and Cohort 1B were 19.3 months and 13.0 months, respectively (Data cutoff date: May 27, 2024).

The study results demonstrated promising anti-tumor activity, and manageable safety of sac-TMT in combination with tagitanlimab as a first-line treatment for advanced or metastatic NSCLC patients. A total of 40 patients in Cohort 1A and 63 patients in Cohort 1B were included in the full analysis set (FAS) for efficacy assessment. In Cohort 1A and Cohort 1B, respectively, the confirmed objective response rates (ORRs) were 40.0% (95% CI: 24.9–56.7) and 66.7% (95% CI: 53.7–78.0), and the ORRs were:

• 44.4% and 64.7% among patients with non-squamous carcinoma, 36.4% and 69.0% with squamous carcinoma;
• 41.7% and 57.1% among patients with PD-L1 tumor proportion score (TPS) <1%;
• 38.5% and 63.2% for TPS 1–49%;
• 40.0% and 78.3% for TPS ≥50%.

The median progression-free survival (mPFS) for Cohort 1A was 15.4 months (95% CI: 6.7–17.9) and not reached (95% CI: 9.6–NE) for Cohort 1B.

The most common grade ≥3 treatment-related adverse events (TRAEs) for both Cohorts 1A and 1B were decreased neutrophil count, decreased white blood cell count and anemia. No treatment-related deaths were observed.

Subgroup analyses showed consistent efficacy across PD-L1 and TROP2 expression levels, as well as in both squamous and non-squamous histological subtypes.

Dr. Michael Ge, CEO of Kelun-Biotech, commented: "The OptiTROP-Lung01 study supports the promising efficacy and safety of sacituzumab tirumotecan in combination with tagitanlimab as a first-line treatment for patients with advanced NSCLC. The results were observed across PD-L1/TROP2 expression levels and histological subtypes and support the advancement potential of sac-TMT from later-line to front-line therapy. The publication of results from several studies in top-tier international journals reflects the recognition of our innovation-driven development strategy. We will continue to work to address critical clinical challenges and unmet medical needs, striving to deliver more therapeutic options and improve quality of life for patients."

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, breast cancer (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 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, Macao, and Taiwan).

To date, two indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with 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) and 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 HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting were accepted by the CDE, 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 III global clinical studies of sac-TMT as a monotherapy or with pembrolizumab^[1] or other agents for several types of cancer. These studies are sponsored and led by MSD.

About Tagitanlimab

Tagitanlimab is the first PD-L1 mAb globally to receive authorization for the first-line treatment of NPC. Previously, the NMPA has approved the marketing in China of tagitanlimab used in combination with cisplatin and gemcitabine for the first-line treatment of patients with R/M NPC and monotherapy for the treatment of patients with recurrent or metastatic NPC who have failed after prior 2L+ chemotherapy, respectively.

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, 1 project is 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 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/.

https://doi.org/10.1038/s41591-025-03883-5

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SOURCE Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd.