Phase II Results of Sacituzumab Tirumotecan (sac-TMT) plus Pembrolizumab in Advanced Urothelial Carcinoma Presented at 2026 ESMO

CHENGDU, China, Oct. 24, 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 held in Madrid, updated results from the Phase II MK-2870-002/SKB264-II-06 study of sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870)(佳泰莱^®) plus MSD’s^[1] anti-programmed cell death protein 1 (PD-1) monoclonal antibody pembrolizumab (KEYTRUDA^®[2]) in locally advanced or metastatic urothelial carcinoma (la/mUC) were presented as a rapid oral report by Professor Xiaojie Bian from Fudan University Shanghai Cancer Center (4739RO; Rapid oral | Genitourinary Tumours, Renal and Urothelial).

This is an international, multicenter, open-label, multi-cohort Phase II basket trial. Cohort B enrolled a total of 40 patients with la/mUC who had not previously received systemic therapy and were cisplatin-ineligible; patients received sac-TMT 4 mg/kg or 5 mg/kg in combination with pembrolizumab.

As of January 26, 2026, with a median follow-up of 22.8 months, the efficacy data showed:

• Confirmed objective response rate (ORR) was 68%, and confirmed disease control rate (DCR) was 88%; median duration of response (DOR) was 19.4 months; responses were observed irrespective of trophoblast cell-surface antigen 2 (TROP2) and programmed cell death ligand 1 (PD-L1) expression.
• Median progression-free survival (PFS) was 11.2 months (95% CI: 5.8-not reached (NR)); median overall survival (OS) was NR (95% CI: 17.2-NR).

In terms of safety, 63% of patients experienced grade ≥3 treatment-related adverse events (TRAEs), most commonly anemia, decreased neutrophil count and stomatitis. Only a small number of patients developed ocular surface toxicity (all were grade ≤2), and no patients experienced interstitial lung disease/pneumonitis. The incidence of TRAEs leading to permanent discontinuation of sac-TMT was 8%, and no fatal TRAEs occurred.

The study showed that sac-TMT plus pembrolizumab demonstrated promising antitumor activity in cisplatin-ineligible patients with previously untreated la/mUC, regardless of TROP2 and PD-L1 expression levels. The combination regimen had a manageable safety profile, consistent with the known safety profiles of each monotherapy. These data support the initiation of global Phase III TroFuse-055 study (NCT07829783).

Professor Xiaojie Bian from Fudan University Shanghai Cancer Center said: "Sac-TMT, a TROP2-targeting ADC, combined with pembrolizumab as an ADC+IO regimen, has demonstrated encouraging efficacy in first-line cisplatin-ineligible patients with locally advanced or metastatic urothelial carcinoma, with a favorable safety profile for long-term dosing. We look forward to further exploration in subsequent studies."

About sac-TMT(佳泰莱^®)

Sac-TMT, a core product of the Company, is a novel TROP2 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 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) 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+)/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 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 the 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/.