At the American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium 2025, to be held in San Francisco, USA, from Feb. 13-15, 2025, Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd （"Kelun-Biotech" will present efficacy and safety results from the Phase 1/2 KL264-01/MK-2870-001 study (NCT04152499) of its anti-TROP2 ADC sacituzumab tirumotecan (sac-TMT, formerly SKB-264/MK-2870) as monotherapy in patients with unresectable, locally advanced or metastatic urothelial carcinoma (UC) who progressed on or after prior anti-cancer therapies. These findings will be presented in a poster session on February 14, 2025, local time (Abstract #796).

The abstract for the above study was also published on the official website of the ASCO GU Cancers Symposium 2025 on February 10, 2025, local time.

UC

Eligible participants had histologically/cytologically confirmed locally advanced or metastatic UC, had experienced progression of disease on ≥1 prior line of platinum-based therapy and had received prior anti-PD-(L)1 therapy; platinum-ineligible patients were eligible if they received prior anti-PD-(L)1 therapy (prior neoadjuvant/adjuvant therapy counted as a line of therapy if patients progressed within 12 months). Patients had Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤1 and measurable disease by CT/MRI. Patients received sac-TMT 5 mg/kg every two weeks (Q2W) until progression of disease, unacceptable toxicity or withdrawal of consent.

As of data cutoff on June 30, 2024, 49 treated patients had a minimum follow-up of ≥9 weeks. Eleven patients received sac-TMT as 2L treatment; 38 received sac-TMT as 3L+ treatment. Median age was 62 and 61 years old, respectively; most patients were Asian (82%; 100%). Median (range) follow-up was 9.5 (7.5-16.2) months and 11.7 (7.8-17.4) months, respectively. Among all patients, objective response rate (ORR) was 31%.  Among all patients, objective response rate (ORR) was 31%. Efficacy data are shown below:

CI=Confidence interval, CR=Complete response, PR=Partial response, SD=Stable disease, PD=Progression of disease, DoR=Duration of response, PFS=Progression-free survival, OS=Overall survival, NE=Not evaluable.

"+" No progressive disease or death as of last disease assessment.

a Includes all patients as-treated.

b Kaplan-Meier method for censored data.

By safety data cutoff (May 21, 2024), grade ≥3 treatment-related adverse events (TRAEs) occurred in 59% of patients. The most common Grade 3-4 TRAEs were anemia (39%), neutrophil count decreased (29%), white blood cells count decreased (16%), stomatitis (12%), and platelet count decreased (8%), which were generally reversible with dose modifications and/or supportive care. No Grade 5 TRAEs occurred; TRAEs led to sac-TMT discontinuation in one patient.

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.

Previously, the National Medical Products Administration (NMPA) has approved the marketing of sac-TMT in China for 2L+ advanced triple negative breast cancer (TNBC), and accepted two supplemental new drug applications (sNDA) seeking the approvals of sac-TMT monotherapy for 2L/3L EGFR-mutant non-small cell lung cancer (NSCLC).

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).

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 or novel ADC projects in clinical or preclinical research stage.