Promising Results for Patritumab Deruxtecan in Treating Metastatic Breast Cancer

Researchers from the National Institute of Health and Medical Research have announced encouraging findings from the ICARUS-BREAST 01 study, which evaluated the efficacy and safety of patritumab deruxtecan (HER3-DXd) in patients with hormone receptor-positive metastatic breast cancer. The study involved 99 patients who had already received multiple treatments, including hormone therapy, chemotherapy, and targeted therapies. The results showed that over 53% of patients experienced a significant reduction in tumour size, with some experiencing complete disappearance of visible signs of disease.

Key Takeaways:

• The ICARUS-BREAST 01 study demonstrated the efficacy of patritumab deruxtecan (HER3-DXd) in treating metastatic breast cancer, with 53.5% of patients experiencing a significant reduction in tumour size.
• The study found that the response to the drug may be linked to how HER3 is distributed within the tumour and to the absence of certain mutations, such as ESR1.
• Patients with tumours expressing higher levels of HER3 were found to have disease control for longer periods.
• The most common adverse events were fatigue, nausea, and diarrhoea, consistent with the previously reported safety profile.
• The study highlighted interesting biological insights that could help identify patients most likely to benefit from this approach.

Statistics:

• 99 patients participated in the ICARUS-BREAST 01 study.
• 53.5% of patients experienced a significant reduction in tumour size with patritumab deruxtecan.
• Around 63% of patients derived clinical benefit from the treatment.
• The median follow-up period was 15.3 months.
• Median progression-free survival was 9.2 months.
• The average duration of response was 9.3 months.

Sources:

• National Institute of Health and Medical Research
• Nature Medicine
• Siegel RL, Giaquinto AN, Jemal A. Cancer statistics, 2024. CA: A Cancer Journal for Clinicians 2024;74(1):12--49