SKB BIO-B (06990) announced that its TROP2-targeting antibody-drug conjugate (ADC), sacituzumab govitecan (sac-TMT, also known as SKB264/MK-2870), has received approval from China's National Medical Products Administration (NMPA) for a new indication. The approval covers the treatment of adult patients with unresectable or metastatic hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer who have received prior endocrine therapy and at least one line of chemotherapy for advanced disease. This marks the fourth approved indication for sac-TMT in China. The approval is based on positive results from the OptiTROP-Breast02 Phase 3 clinical study, which was presented as a late-breaking abstract in an oral session at the 2025 European Society for Medical Oncology (ESMO) Congress. The OptiTROP-Breast02 study evaluated the efficacy and safety of sac-TMT monotherapy compared to investigator's choice of chemotherapy in patients with unresectable or metastatic HR+/HER2- breast cancer. In this Phase 3 trial, 95.7% of enrolled patients had visceral metastases at baseline, and 75.9% had liver metastases. Regarding HER2 status, 52.9% of patients had HER2-zero expression (IHC 0), and 47.1% had HER2-low expression (IHC 1+ or IHC 2+/ISH-). All patients had previously been treated with a CDK4/6 inhibitor and a taxane. In the advanced or metastatic setting, 56.6% of patients had received two or more prior lines of chemotherapy. Results showed that the sac-TMT group demonstrated a statistically significant and clinically meaningful improvement in Blinded Independent Central Review (BICR)-assessed progression-free survival (PFS) compared to the chemotherapy group (8.3 months vs. 4.1 months; hazard ratio [HR], 0.35; 95% confidence interval [CI]: 0.26-0.48; p<0.0001). Consistent PFS benefits were observed across all pre-specified subgroups, including HER2-zero and HER2-low expression, number of prior chemotherapy lines in the advanced/metastatic setting, presence of baseline visceral metastases, presence of baseline liver metastases, and duration of prior CDK4/6 inhibitor therapy. BICR-assessed PFS results for the HER2-zero and HER2-low expression subgroups showed hazard ratios of 0.39 (95% CI: 0.26-0.57) and 0.31 (95% CI: 0.20-0.48), respectively. Furthermore, a trend towards overall survival (OS) benefit and a significantly improved objective response rate (ORR) were observed compared to the chemotherapy group (41.5% vs. 24.1%). Global (NCT06312176) and China-specific (NCT07071337) Phase 3 clinical studies evaluating sac-TMT with or without pembrolizumab for the treatment of HR+/HER2- breast cancer patients who have received prior endocrine therapy but no prior chemotherapy have now been initiated.
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