SystImmune, in collaboration with Bristol-Myers Squibb, will showcase new data from an ongoing Phase 1 clinical trial evaluating Izalontamab Brengitecan (iza-bren) at the upcoming European Society for Medical Oncology (ESMO) Breast Cancer 2025 Annual Meeting in Munich, Germany this May.
Innovative Bispecific ADC Targeting EGFR and HER3
Izalontamab Brengitecan is a first-in-class bispecific antibody-drug conjugate (ADC) designed to target EGFR and HER3, two growth factor receptors frequently overexpressed in epithelial tumors. The tetravalent ADC links these two targeting domains to a novel topoisomerase inhibitor payload (Ed-04), a camptothecin derivative, via a stable, cleavable tetrapeptide linker.
By simultaneously binding EGFR and HER3, Izalontamab Brengitecan blocks proliferative and survival signaling pathways in cancer cells. Following internalization and lysosomal trafficking, the ADC releases its cytotoxic payload, triggering genotoxic stress pathways that lead to targeted cancer cell death.
Phase 1 Trial and Efficacy in HER2-Negative Breast Cancer
At ESMO Breast 2025, SystImmune will present updated Phase 1 clinical data from patients with locally advanced or metastatic HER2-negative (IHC 0, 1+, or 2+/ISH-) breast cancer treated with Izalontamab Brengitecan at 2.5 mg/kg on Days 1 and 8 every three weeks. Importantly, patients were not selected based on EGFR or HER3 expression, demonstrating the ADC’s broad potential applicability.
Additional subgroup analyses, previously disclosed at the 2024 San Antonio Breast Cancer Symposium (SABCS), confirmed encouraging clinical efficacy and a manageable safety profile in heavily pretreated patients, including those with HER2 0 tumors.
Addressing Unmet Needs in Breast Cancer Treatment
“These data continue to support our belief that Izalontamab Brengitecan demonstrates robust clinical efficacy across a variety of tumor types, such as breast cancer, including HER2-negative subtypes, with a manageable safety profile,” said Jonathan Cheng, MD, Chief Marketing Officer of SystImmune.
Dr. Cheng emphasized the potential of Izalontamab Brengitecan as an important treatment option addressing unmet medical needs for patients with limited therapies available.
“We remain committed to advancing this therapy through clinical trials, exploring its potential not only as a monotherapy but also in combination with other agents to improve outcomes for cancer patients worldwide,” he concluded.
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