Kelun-Biotech Unveils Promising Phase 3 Results for Breast Cancer Treatment

Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. reported positive outcomes from a Phase 3 clinical study of sacituzumab tirumotecan, a targeted therapy for advanced hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. The findings were presented by Professor Man Li during the 2025 European Society for Medical Oncology (ESMO) Congress held in Berlin, Germany, on October 18, 2025.

The study, known as OptiTROP-Breast02, involved 399 patients who had previously received treatment with CDK4/6 inhibitors and at least one line of chemotherapy. Participants were randomized in a 1:1 ratio to receive either sacituzumab tirumotecan or investigator’s choice of chemotherapy. Results indicated a significant improvement in median progression-free survival (PFS) for the sacituzumab group, with a median of 8.3 months compared to 4.1 months for the chemotherapy group, yielding a hazard ratio (HR) of 0.35 (95% confidence interval [CI], 0.26-0.48; P<0.0001). The clinical benefits of sacituzumab tirumotecan were consistent regardless of HER2 expression levels. Specifically, the HR for PFS was 0.39 (95% CI, 0.26-0.57) among patients with HER2-zero tumors and 0.31 (95% CI, 0.20-0.48) among those with HER2-low expression. The study also indicated a trend favoring overall survival (OS) for sacituzumab tirumotecan, with an HR of 0.33 (95% CI, 0.18-0.61).

The safety profile of sacituzumab tirumotecan was found to be manageable, with grade ≥3 treatment-related adverse events (TRAEs) occurring in 62.0% of patients receiving sacituzumab compared to 64.8% in the chemotherapy group. Notably, no patients in the sacituzumab group discontinued due to TRAEs, while only 0.5% of patients in the chemotherapy group did so. Pneumonitis was observed in 1.5% of sacituzumab patients and 1.0% in those receiving chemotherapy, both classified as grade 1-2.

Significance of the Findings

The results from the OptiTROP-Breast02 study are particularly significant as they represent the first Phase 3 clinical trial focused exclusively on an all-Chinese population with HR+/HER2- breast cancer. Professor Man Li remarked, “The Phase III OptiTROP-Breast02 study confirmed that, regardless of HER2 expression status, sac-TMT demonstrated promising efficacy in previously treated HR+/HER2- BC patients.” He emphasized that the study offers both evidence-based support for treatment and a reliable option for patients.

Following the positive results, sacituzumab tirumotecan has been accepted for new indication applications by the National Medical Products Administration (NMPA) in China, which is currently under priority review. Kelun-Biotech is also conducting other clinical trials, including a Phase III study assessing sacituzumab tirumotecan as monotherapy and in combination with pembrolizumab for chemotherapy-naïve HR+/HER2- breast cancer, aiming to enroll approximately 1,200 participants globally.

About Sacituzumab Tirumotecan

Sacituzumab tirumotecan, marketed under the name 佳泰莱, is a novel antibody-drug conjugate targeting TROP2, a protein often overexpressed in various solid tumors, including breast cancer. The drug utilizes a proprietary linker to deliver a topoisomerase I inhibitor directly to cancer cells, aiming to induce apoptosis and inhibit tumor growth.

To date, sacituzumab tirumotecan has been approved for several indications in China, including treatment for unresectable locally advanced or metastatic triple-negative breast cancer and specific types of non-small cell lung cancer. The drug is notable for being the first TROP2-targeting ADC approved for lung cancer globally.

Kelun-Biotech continues to expand its research and development initiatives, with multiple ongoing projects aimed at addressing unmet medical needs in both China and international markets. The company is committed to becoming a leading global player in innovative drug development, focusing on diseases with significant treatment gaps.

For further information about their ongoing research and products, visit https://kelun-biotech.com/.