Final OS Analysis Results from Phase III OptiTROP-Lung04 Study of Sacituzumab Tirumotecan (sac-TMT) Presented at 2026 ESMO

• Median OS was extended by 8.5 months compared with platinum-based doublet chemotherapy (25.9 vs 17.4 months), with a 31% reduction in the risk of death (HR 0.69; 95% CI 0.54–0.89; one-sided P = 0.0021).
• The 2-year OS rate was 54.1% vs 37.2%, an improvement of 16.9%; with a median follow-up of 32.3 months, the survival benefit was sustained.
• The adjusted median OS differed by 9.3 months (25.9 vs 16.6 months): after adjusting for the subsequent therapy with an ADC using the prespecified RPSFT model, the risk of death was reduced by 43% (HR 0.57; 95% CI 0.42–0.75).

CHENGDU, China, Oct. 25, 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 prespecified final overall survival (OS) analysis results of the Phase III OptiTROP-Lung04 study of sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870) (佳泰莱^®) were presented as an oral presentation by Professor Wenfeng Fang from the Sun Yat-sen University Cancer Center (LBA67; Proffered paper | NSCLC, Metastatic). The results showed that in patients with epidermal growth factor receptor (EGFR)-mutant locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who have progressed after treatment with EGFR-tyrosine kinase inhibitor (EGFR-TKI) therapy, sac-TMT monotherapy demonstrated a sustained OS benefit compared with platinum-based doublet chemotherapy.

The results of the final progression-free survival (PFS) analysis and interim OS analysis of the study were published online in The New England Journal of Medicine in 2025. The final PFS analysis assessed by blinded independent central review (BICR) showed a 51% reduction in the risk of disease progression or death (HR 0.49; 95% CI 0.39–0.62). Based on these results, sac-TMT was approved by the National Medical Products Administration (NMPA) of China in September 2025 for the treatment of adult patients with EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy.

The final OS analysis results showed that, after a median follow-up of 32.3 months, sac-TMT demonstrated a sustained and clinically meaningful OS improvement compared with platinum-based doublet chemotherapy. In addition, 22.6% of patients in the platinum-based doublet chemotherapy group received subsequent therapy with an antibody-drug conjugate (ADC), the prespecified rank-preserving structural failure time (RPSFT) model-adjusted analysis provided supplemental support for the OS primary analysis.

In terms of safety, no new safety signals were identified after extended follow-up. The most common treatment-related adverse events were hematological adverse events and stomatitis. Stomatitis was mostly Grade 1–2 and manageable, with incidence of Grade 3 events being 4.8%. Interstitial lung disease/pneumonitis was reported in only 1 case (0.5%) in the sac-TMT group and 2 cases (1.1%) in the platinum-based doublet chemotherapy group, all of which were Grade 1–2.

Professor Wenfeng Fang from the Sun Yat-sen University Cancer Center said: "For patients who progress after EGFR-TKI therapy, extended survival is an important treatment goal. This final OS analysis further clarifies that, compared with platinum-based doublet chemotherapy, sac-TMT monotherapy significantly prolongs OS and reduces the risk of death by 31%, providing more mature long-term follow-up evidence for treatment options in this population."

OptiTROP-Lung04 study

OptiTROP-Lung04 is a randomized, multicenter, open-label Phase III study. A total of 376 patients were enrolled and randomized (1:1) to receive sac-TMT monotherapy (5 mg/kg Q2W) or platinum-based doublet chemotherapy (pemetrexed plus platinum). The primary endpoint was BICR-assessed PFS, and OS was a key secondary endpoint. As of the data cut-off date of August 6, 2026, the median follow-up was 32.3 months.

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 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 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 EGFR-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+)/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 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 programmed cell death ligand 1 (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