Novel Antibody-Drug Conjugate Showed Promise Among Patients With Advanced Breast Cancer With Low HER2 Expression
According to a non-randomized, open-label phase 2 study, the novel antibody-drug conjugate (ADC), MRG002, demonstrated manageable safety and anti-tumor potential among patients with locally advanced or metastatic breast cancer with low HER2 expression.
This novel ADC, MRG002, targets HER2 with a monomethyl auristatin E (MMAE) payload. This phase 2 trial enrolled 56 patients with locally advanced or metastatic breast cancer with low HER2 expression, including patients from both HR-positive and HR-negative disease. All patients had failed on at least 1 line of standard therapy. Patients received 2.6 mg/kg of MRG002 every 3 weeks with imaging evaluations every 6 weeks.
The confirmed objective response rate (ORR) as assessed by independent review committee was 39.3%, with a disease control rate of 73.2%. The median progression-free survival was 5.8 months. Overall survival (OS) data were immature, and the 12-month OS rate was 79.9%. The most common grade 3/4 treatment-related adverse events that occurred in ≥5% of patients included decreased neutrophil count, decreased white blood cell count, and peripheral neuropathy. There was 1 patient who experienced grade 2 interstitial lung disease. No treatment-related deaths occurred.
Study authors concluded “MRG002 demonstrated a manageable safety profile and promising anti-tumor activity in patients with locally advanced or metastatic breast cancer with low HER2 expression.”
Source:
Zhang S, Sun T, Wang X, et al. Efficacy and safety of MRG002 monotherapy in treating patients with locally advanced or metastatic breast cancer with low HER2 expression: A multi-centre, non-randomized, open-label phase II clinical trial. Published online September 18, 2025. doi: 10.1016/j.ejca.2025.115794
