On November 27, 2025 Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech", HKEX: 6990) reported TROP2 ADC sacituzumab tirumotecan (sac-TMT) monotherapy for advanced or metastatic urothelial carcinoma (UC) patients has been published in the journal of Annals of Oncology (Impact Factor: 65.4). This study provides the first evidence of sac-TMT’s potential significant clinical benefit for patients with advanced UC.
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This publication is based on the efficacy and safety results of cohort 9 of a phase II MK-2870-001/KL264-01 study evaluating sac-TMT monotherapy in patients with advanced or metastatic UC and disease progression after chemotherapy and immune checkpoint inhibitors. Sac-TMT employs the only currently available irreversible conjugation technology, combined with the novel toxin – a topoisomerase I inhibitor KL610023 (T030). This enhances stability, ensuring greater release of the toxin T030 at tumor sites. It guarantees precise and potent tumor cell killing, achieving an effective balance between efficacy and safety. With its unique structural design, sac-TMT has demonstrated outstanding therapeutic potential in clinical studies.
The results showed that sac-TMT 5 mg/kg monotherapy every 2 weeks demonstrated promising antitumor activity in participants with heavily pretreated advanced or metastatic UC, with a manageable safety profile, warranting further evaluation of sac-TMT in this population.
As of data cutoff (February 17, 2025), 49 participants were treated with sac-TMT; 37 (76%) had received ≥2 prior lines of therapy. Median follow-up was 18.8 months. The confirmed ORR was 31% (sac-TMT as second-line therapy demonstrated a confirmed ORR of 50%) and the disease control rate was 71%. Median DOR was not reached, and the 12-month probability of sustained response was 53%. Median PFS was 5.5 months, with 12-month PFS rate was 29%. Safety with sac-TMT was manageable, the most frequent grade 3 or 4 treatment-related adverse events (AEs) (≥5%) were hematologic toxicities and stomatitis, with no febrile neutropenia events or grade 5 treatment-related AEs.
Professor Ye Dingwei, Vice President of Fudan University Shanghai Cancer Center, stated, "Traditional chemotherapy has limited efficacy for advanced or drug-resistant UC. The emergence of precision medicines like ADCs is breaking through treatment bottlenecks for patients with poor response to chemotherapy. We are delighted to observe the encouraging clinical outcomes achieved by the sac-TMT monotherapy regimen, particularly its outstanding efficacy even among heavily pretreated patients. This development injects new momentum into the treatment landscape for advanced UC and offers patients a more precise therapeutic option."
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 non-small cell lung cancer (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 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, three indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with 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), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the world’s first TROP2 ADC drug approved for marketing in lung cancer. In addition, the sNDA for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA), and was included in the priority review and approval process.
As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 15 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.
(Press release, Kelun, NOV 27, 2025, View Source [SID1234660992])