Kelun-Biotech Unveils Promising Phase 3 Study Results for Breast Cancer Drug

Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. announced significant findings from its Phase 3 clinical study, OptiTROP-Breast02, for the drug sacituzumab tirumotecan (sac-TMT) on October 18, 2025. Presented at the European Society for Medical Oncology (ESMO) Congress in Berlin, Germany, the study focused on patients with advanced hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer.

The study revealed that sac-TMT significantly improved progression-free survival (PFS) compared to the investigator’s choice of chemotherapy. The median PFS for patients receiving sac-TMT was reported at 8.3 months, in contrast to 4.1 months for those on chemotherapy (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.26-0.48; P<0.0001). These results were presented by Professor Man Li from the Second Affiliated Hospital of Dalian Medical University during a proffered paper session focused on metastatic breast cancer (Presentation #LBA23).

The OptiTROP-Breast02 study involved 399 patients who had previously been treated with CDK4/6 inhibitors and at least one line of chemotherapy. Participants were randomized in a 1:1 ratio to receive either sac-TMT or chemotherapy. Notably, the clinical benefits of sac-TMT were observed across all predefined subgroups, regardless of HER2 expression status, indicating its potential as a broadly applicable treatment option.

The data further indicated that sac-TMT not only showed a longer duration of response (DoR) but also had a superior overall response rate (ORR) compared to chemotherapy. Although there was a favorable trend towards improved overall survival (OS) with sac-TMT (HR, 0.33; 95% CI, 0.18-0.61), the results are still interpreted with caution as they did not reach statistical significance.

Safety profiles were also evaluated, with grade ≥3 treatment-related adverse events (TRAEs) occurring in 62.0% of patients receiving sac-TMT, compared to 64.8% in the chemotherapy group. Discontinuation due to TRAEs was minimal, with only 0% in the sac-TMT group and 0.5% in the chemotherapy group. Pneumonitis, classified as grade 1-2, was reported in 1.5% and 1.0% of patients in the sac-TMT and chemotherapy groups, respectively.

As a result of these findings, the National Medical Products Administration (NMPA) has already accepted applications for new indications of sac-TMT and prioritized them for review. This approval process allows for expedited access to the treatment for patients in need.

Professor Man Li highlighted that the Phase 3 OptiTROP-Breast02 study offered promising efficacy results for sac-TMT in previously treated HR+/HER2- breast cancer patients. This trial stands out as the first Phase 3 study to focus exclusively on an all-Chinese population with this type of breast cancer, marking a significant advancement in clinical research within China.

In addition to the Phase 3 study already completed, further studies are underway. A global Phase III clinical study is currently investigating sacituzumab tirumotecan as a monotherapy and in combination with pembrolizumab in chemotherapy-naive HR+/HER2- breast cancer, aiming to enroll approximately 1,200 participants. Additionally, a registrational study is enrolling 430 patients in China.

Sac-TMT, also known as 佳泰莱, is a novel human TROP2-directed antibody-drug conjugate (ADC) that targets various advanced solid tumors, including breast cancer, non-small cell lung cancer, and gastric cancer. The drug utilizes a proprietary linker to attach a topoisomerase I inhibitor, KL610023, which causes DNA damage in tumor cells, promoting cell death.

Kelun-Biotech has made strides in the field of innovative pharmaceuticals, focusing on solid tumors and other significant diseases. The company has initiated multiple registrational clinical studies and has already received approval for three indications for sac-TMT in China.

As it moves forward, Kelun-Biotech aims to position itself as a leader in the global market for innovative treatments, addressing unmet medical needs both domestically and internationally. For more information, visit the company’s website at https://kelun-biotech.com/.