AstraZeneca (AZ) and Daiichi Sankyo’s Enhertu (trastuzumab deruxtecan) has been approved by the European Commission (EC) to treat a broader population of HER2-low breast cancer patients.
The drug has been authorised for use as a monotherapy in adults with unresectable or metastatic hormone receptor (HR)-positive, HER2-low or HER2-ultralow breast cancer. Eligible patients will also have received at least one endocrine therapy in the metastatic setting and will not be considered suitable for endocrine therapy as their next line of treatment.
The EC’s decision, which makes Enhertu the first HER2-directed therapy approved for this patient population, follows a recent recommendation from the European Medicines Agency’s human medicines committee and was based on positive results from the phase 3 DESTINY-Breast06 trial.
Data presented at last year’s American Society of Clinical Oncology annual meeting showed that Enhertu was associated with a 38% reduction in the risk of disease progression or death compared to chemotherapy in patients with chemotherapy-naïve HR-positive, HER2-low metastatic breast cancer, with a median progression-free survival (PFS) of 13.2 months versus 8.1 months.
Among the overall study population of patients with chemotherapy-naïve HER2-low or HER2-ultralow metastatic breast cancer, media PFS was 13.2 months in Enhertu-treated patients and 8.1 months in those randomised to receive chemotherapy.
Approximately 557,000 people are diagnosed with breast cancer every year in Europe, with HR-positive, HER2-negative disease accounting for around 70% of all cases. Despite being classed as HER2-negative, many of these tumours still have some level of HER2 expression.
Endocrine-based therapies are typically used in early lines of treatment for HR-positive metastatic breast cancer regardless of HER2 expression. Following this, some patients discontinue treatment, while others are treated with conventional chemotherapy, which is associated with poor response rates and outcomes.
Enhertu is an antibody-drug conjugate that targets HER2 on cancer cells and is already approved in the EU to treat patients with HER2-low breast cancer who have received a prior systemic therapy in the metastatic setting or developed disease recurrence during or within six months of completing adjuvant chemotherapy.
Principal investigator of DESTINY-Breast06, Giuseppe Curigliano, said: “This approval introduces a new treatment option for HR-positive metastatic breast cancers that express HER2.
“In DESTINY-Breast06, Enhertu outperformed chemotherapy, providing PFS of more than one year for patients with HR-positive, HER2-low or HER2-ultralow metastatic breast cancer, demonstrating the benefit of treating these patients with Enhertu instead of chemotherapy.”