Dr. McArthur on the FDA Approval of Second-Line Trastuzumab Deruxtecan in HER2+ Breast Cancer

Heather McArthur, MD, MPH, associate professor in the Department of Internal Medicine and clinical director of the Breast Cancer Program at Simmons Cancer Center, University of Texas Southwestern Medical Center, discusses the FDA approval of fam-trastuzumab deruxtecan-nxki (Enhertu) for second-line treatment in HER2-positive metastatic breast cancer.

On May 4, 2022, the FDA approved trastuzumab deruxtecan for adult patients with unresectable or metastatic HER2-positive breast cancer who have previously received an anti–HER2-based regimen either in the metastatic setting, or in the neoadjuvant or adjuvant setting, and have developed disease recurrence during or within 6 months of therapy completion. Findings from the phase 3 DESTINY-Breast03 trial (NCT03529110) served as the confirmatory trial for the approval.

In DESTINY-Breast03, trastuzumab deruxtecan was compared with ado-trastuzumab emtansine (T-DM1; Kadcyla), which was the previous standard of care based on results from the EMILIA study (NCT00829166) McArthur says. Results from DESTINY-Breast03 showed improved progression-free survival (PFS) vs T-DM1 in patients with HER2-positive, unresectable or metastatic breast cancer, McArthur adds.

Specifically, the 12-month PFS rate with trastuzumab deruxtecan was 76% vs 34% with T-DM1, McArthur notes. Additionally, trastuzumab deruxtecan displayed a 45% reduction in the risk of death vs T-DM1, McArthur explains.

Overall, the benefits of trastuzumab deruxtecan have been observed across patient subgroups, establishing this treatment as a new standard of care in the second line, McArthur concludes.