Dr. Hurvitz on the Results of Subgroup Analyses From DESTINY-Breast03 in HER2+ Breast Cancer

Sara A. Hurvitz, MD, associate professor, David Geffen School of Medicine, University of California, Los Angeles (UCLA), medical oncologist, medical director, Jonsson Comprehensive Cancer Center Clinical Research Unit, co-director, Santa Monica-UCLA Outpatient Oncology Practices, director, Breast Cancer Clinical Trials Program, UCLA, discusses the results of subgroup analyses from the phase 3 DESTINY-Breast03 trial (NCT03529110) in patients with HER2-positive metastatic breast cancer.

The DESTINY-Breast03 trial randomized patients with HER2-positive metastatic breast cancer who were previously treated with trastuzumab (Herceptin) and a taxane to fam-trastuzumab deruxtecan-nxki (Enhertu) vs ado-trastuzumab emtansine (T-DM1; Kadcyla). Initial results demonstrated a clinically meaningful progression-free survival (PFS) benefit with trastuzumab deruxtecan vs T-DM1 in this patient population.

During the 2021 San Antonio Breast Cancer Symposium, updated results from exploratory subgroup analyses of the study were presented. The findings showed that trastuzumab deruxtecan induced PFS and overall response rate (ORR) improvements vs T-DM1 across patients irrespective of hormone receptor status, prior pertuzumab (Perjeta), number of prior lines of therapy, and presence or absence of visceral disease.

Notably, patients with baseline brain metastases also derived a PFS and ORR benefit with trastuzumab deruxtecan vs T-DM1. In patients with stable brain metastases at baseline, the median PFS was 15 months with trastuzumab deruxtecan vs 3 months with T-DM1. The ORRs were 67.4% vs 20.5%, respectively.