BMS Presents Promising Data for EGFRxHER3 Antibody-Drug Conjugate at ESMO 2025

Bristol Myers Squibb (BMS) has unveiled encouraging results from an early-stage trial of its EGFRxHER3 antibody-drug conjugate (ADC), izalontamab brengitecan (iza-bren), at the 2025 European Society for Medical Oncology (ESMO) Congress in Berlin. The data suggest that BMS may be positioned to maintain a competitive edge in the evolving ADC landscape.

Global Trial Results Show Consistent Efficacy

The phase 1 study, which included 113 patients across various cancer types, demonstrated a confirmed overall response rate (cORR) of 55% in a cohort of 20 patients receiving a 2.5-mg/kg dose on Days 1 and 8 of a three-week cycle. This marks the first readout from a global trial of iza-bren, following previously released China-only data.

Notably, the trial showed promising results across different cancer types:

• Non-small cell lung cancer (NSCLC): 42.9% cORR (14 patients)
  • EGFR-mutant: 36.4% cORR (11 patients)
  • EGFR-wildtype: 66.7% cORR (3 patients)
• Breast cancer: 100% cORR (3 patients)

Dr. Anne Kerber, head of development, hematology, oncology and cell therapy at BMS, emphasized the importance of consistency between global and Chinese data sets, stating, "That's what we do see—and that's what is very encouraging for us."

Safety Profile and Future Developments

The most frequent treatment-related adverse events were hematologic, with neutropenia, anemia, and thrombocytopenia of grade 3 or above occurring in 55%, 28%, and 12% of patients, respectively. Dr. Kerber noted that these rates might be influenced by the heavily pretreated patient population and the absence of prophylactic measures in the trial.

BMS is currently evaluating iza-bren in a global phase 2/3 study as a first-line treatment for triple-negative breast cancer and bladder cancer, with plans to assess its potential in lung cancer as well. The company expects to move forward with the 2.5-mg/kg dose regimen, although a final decision is pending.

Strategic Importance and Competitive Landscape

Iza-bren, acquired through an $800 million upfront payment to SystImmune as part of a deal worth up to $8.4 billion, is considered by some analysts to be an underappreciated asset in BMS's oncology pipeline. The ADC's design, which targets both EGFR and HER3 receptors involved in epithelial tumor survival and proliferation, positions it as a potentially versatile treatment option.

While other companies, including Duality Biotherapeutics, Avenzo Therapeutics, and CStone Pharmaceuticals, are developing similar EGFRxHER3 ADCs, BMS appears confident in its lead. Dr. Kerber stated, "Right now, given the breadth of the data that we have at this point in time not only in China, but also in the global population, I think we're pretty confident that we will be able to stay ahead of the competition."

As the pharmaceutical industry continues to invest in ADC technology, the progress of iza-bren represents a significant development in the field, potentially offering new treatment options for patients with various types of cancer.