Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. announced that the Company will present the updated efficacy and safety results from a phase 2 expansion cohort of the innovative TROP2-ADC (SKB264, also known as MK-2870) in patients with previously treated metastatic triple negative breast cancer (mTNBC) during a poster spotlight session at the 2023 San Antonio Breast Cancer Symposium (SABCS) to be held in San Antonio, Texas, the United States of America from December 5 to 9, 2023. The study results are summarized as follows: As of the data cut-off date (May 5, 2023), 59 mTNBC patients were enrolled and treated with SKB264 (MK-2870) at 4 or 5 mg/kg Q2W. 88% of patients had received 3 prior lines of therapy for metastatic disease.

The median follow-up was 22.8 months. The objective response rate (ORR) was 42.4% and disease control rate (DCR) was 76.3%. The median duration of response (mDoR) was 11.5 months.

Median progression-free survival (mPFS) was 5.7 months. Median overall survival (mOS) was 16.8 months, while 12-month and 24-month OS rates were 65.0% and 39.5%, respectively. In the subset of patients with high TROP2 expression (H-score 200, n=32), ORR was 53.1%, mDoR was 11.1 months, mPFS was 5.8 months, mOS was not reached, while 12- month and 24-month OS rates was 65.3% and 57.3%, respectively.

The most common Grade 3 treatment-related adverse events (TRAEs) (10%) were neutrophil count decreased, white blood cell count decreased, anemia and platelet count decreased. No cases of interstitial lung disease (ILD), neuropathy or Grade 3 diarrhea were observed. No deaths associated with TRAEs were observed.

SKB264 (MK- 2870) was granted Breakthrough Therapy Designation by the Center for Drug Evaluation of the National Medical Products Administration of China for locally advanced or metastatic TNBC in July 2022. On August 13, 2023, the Company announced that a pivotal phase 3 study of SKB264 (MK-2970) in TNBC patients who have failed at least 2 prior lines of therapy for advanced or metastatic setting met the primary endpoint for the study. 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 SKB264 (MK-2770) in all territories outside of Greater China (includes Mainland China, Hong Kong, Macao, and Taiwan).