SystImmune, Inc. (SystImmune), a clinical-stage biotechnology company, and Bristol Myers Squibb (NYSE: BMY)  announced that SystImmune’s parent company, Sichuan Biokin Pharmaceutical Co., Ltd. (Biokin), reported positive topline results from a pre-specified interim analysis of a Phase III study (BL-B01D1-307) evaluating izalontamab brengitecan (iza-bren), an EGFR×HER3 bispecific antibody-drug conjugate (ADC), in patients with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC) whose disease progressed following prior taxane therapy.

In the pre-specified interim analysis, topline results showed that iza-bren demonstrated statistically significant and clinically meaningful improvement in both progression-free survival (PFS) and overall survival (OS) compared to chemotherapy of physician’s choice, meeting both dual primary endpoints.

This Phase III study represents the third Phase III trial in which iza-bren has achieved its primary endpoint(s). It is the first bispecific ADC in a Phase III study to report dual positive PFS/OS results in the treatment of triple-negative breast cancer.

“Patients with advanced triple-negative breast cancer who progress after standard therapies face an urgent need for more effective options,” said Dr. Yi Zhu, Chief Executive Officer of Biokin “These topline results further strengthen our confidence in iza-bren’s potential to deliver meaningful clinical benefit across multiple cancers.”

“These results underscore the potential of bispecific ADC technology targeting both EGFR and HER3 to meaningfully change outcomes in difficult‑to‑treat cancers,” said Cristian Massacesi, Executive Vice President, Chief Medical Officer and Head of Development at Bristol Myers Squibb. “We look forward to advancing the science and development of ADCs, with the hope of uncovering new options for people living with cancer.”

These data will be presented at an upcoming medical meeting.

The BL-B01D1-307 study is sponsored by SystImmune’s parent company, Sichuan Biokin Pharmaceutical Co., Ltd. (Biokin), in Mainland China. Outside of China, iza-bren is jointly developed by SystImmune and Bristol Myers Squibb (BMS) under a collaboration and exclusive license agreement.

The Center for Drug Evaluation (CDE) under China’s National Medical Products Administration (NMPA) granted Breakthrough Therapy Designation (BTD) to iza-bren for the treatment of seven indications, and the U.S. FDA has granted BTD to iza-bren for previously treated NSCLC patients with an EGFR mutation. The New Drug Applications (NDAs) for two indications of iza-bren, for the treatment of locally advanced or metastatic nasopharyngeal carcinoma and for the treatment of recurrent or metastatic esophageal squamous cell carcinoma, have been accepted by the CDE and included in the priority review process.

About BL-B01D1-307
BL-B01D1-307 is a Phase III, randomized, open-label, multi-center clinical study in China, evaluating iza-bren in patients with unresectable locally advanced or metastatic triple-negative breast cancer whose disease progressed following prior taxane therapy. The study includes dual primary endpoints of progression-free survival (PFS) and overall survival (OS).