Final OS Analysis Results of Phase III OptiTROP-Breast01 Study of Sacituzumab Tirumotecan (sac-TMT) Presented as an ESMO Oral Presentation and Simultaneously Published in Annals of Oncology

CHENGDU, China, Oct. 26, 2026 /PRNewswire/ -- Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech" or the "Company", 6990.HK) announced that at the 2026 European Society for Medical Oncology (ESMO) Congress in Madrid, Spain, the results of the final overall survival (OS) analysis of the Phase III OptiTROP-Breast01 study for sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870) (佳泰莱^®) were presented as a rapid oral presentation by Professor Man Li from the Second Hospital of Dalian Medical University (4639RO; Rapid oral | Breast Cancer – Advanced Stage). The results showed that in previously treated patients with locally recurrent or metastatic triple-negative breast cancer (TNBC), sac-TMT demonstrated a sustained survival benefit compared with physician's choice of chemotherapy. These results were also simultaneously published in the oncology journal Annals of Oncology (Impact Factor = 80.4).

The final progression-free survival (PFS) analysis and interim OS analysis results of the study were previously presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting. As assessed by blinded independent central review (BICR), sac-TMT significantly improved PFS compared with chemotherapy (HR 0.32; 95% CI 0.24-0.44); in the prespecified interim OS analysis, sac-TMT showed a statistically significant OS benefit compared with physician's choice of chemotherapy (HR 0.53; 95% CI 0.36-0.78). Based on these results, sac-TMT was approved by the National Medical Products Administration (NMPA) of China in November 2024 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).

The results of this final OS analysis showed that, at a median follow-up of 29.4 months, the results continued to demonstrate the statistically significant OS benefit already confirmed in the prespecified interim analysis:

• The risk of death was reduced by 40%, with an OS HR of 0.60 (95% CI 0.45-0.80) for sac-TMT versus chemotherapy; median OS was 14.7 months and 9.9 months in the two groups, respectively.
• The 30-month OS rate was 26.8% in the sac-TMT group versus 13.2% in the chemotherapy group, the survival benefit was sustained.
• The adjusted risk of death was reduced by 45%: 27.8% of patients in the chemotherapy group received subsequent therapy with an antibody-drug conjugate (ADC), after adjustment using the prespecified rank-preserving structural failure time (RPSFT) model, the OS benefit of sac-TMT remained consistent, with the OS HR of 0.55 (95% CI 0.39-0.73), and median OS was 14.7 months and 9.4 months in the two groups, respectively.

In terms of safety, no new safety signals were identified after extended follow-up. Treatment-related adverse events (TRAEs) in both groups were mainly hematologic toxicities. The incidence of TRAEs leading to treatment discontinuation was 1.5% in each group.

Professor Man Li from the Second Hospital of Dalian Medical University said: "For patients with advanced TNBC who have received multiple lines of therapy and have limited treatment options, sac-TMT monotherapy demonstrated a significant survival benefit compared with chemotherapy. In addition, based on its favorable safety profile and efficacy results, sac-TMT can achieve the dual clinical benefit of prolonging survival and improving quality of life, and help address an unmet need for patients with later-line TNBC."

OptiTROP-Breast01 study:
OptiTROP-Breast01 is a randomized, multicenter, open-label Phase III study where a total of 263 patients were enrolled and randomized 1:1 to receive sac-TMT or physician's choice of chemotherapy. The primary endpoint was BICR-assessed PFS, and OS was a key secondary endpoint. As of the data cut-off date of September 17, 2025, the median follow-up was 29.4 months. The study showed that sac-TMT demonstrated a clinically meaningful and sustained OS benefit versus chemotherapy; the OS benefit was generally consistent across prespecified subgroups, including patients who had previously received programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitor treatment and patients with human epidermal growth factor receptor 2 (HER2)-low expression.

About sac-TMT(佳泰莱^®)

Sac-TMT, a core product of the Company, is a novel trophoblast cell-surface antigen 2 (TROP2)-targeting 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 (KL610023) 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 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 non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy; 4) unresectable or metastatic hormone receptor-positive (HR+)/ 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 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: 1) sac-TMT in combination with pembrolizumab as first‑line treatment for locally advanced or metastatic NSCLC who have PD-L1 tumor proportion score (TPS) ≥1% and are EGFR-negative and ALK-negative; 2) sac‑TMT as first‑line treatment for patients with recurrent or metastatic TNBC who have a PD‑L1 combined positive score (CPS) <10 or have recurred after prior PD‑1/PD‑L1 inhibitor therapy in the early stage, both of the above two applications have been included in the priority review and approval process. As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 18 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 with 8 indications have been approved for marketing, 2 projects with 3 indications are in the 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 with 5 indications 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/. 

SOURCE Kelun-Biotech