Hope S. Rugo, MD, a professor in the Department of Medicine, Hematology/Oncology, and director, Breast Oncology and Clinical Trials Education, University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, discusses the impact of margetuximab in patients with HER2-positive metastatic breast cancer who have an F allele versus V allele, according to findings of the phase III SOPHIA trial. Website: https://www.onclive.com Twitter: / onclive Facebook: / onclive LinkedIn: / onclive