Stuart J. Schnitt, MD - A New View of the Spectrum of HER2 Expression and Significance of HER2 Low in Breast Cancer: Exploring the Biology and Updating Best Practices for Testing and Treatment

Go online to PeerView.com/NRG860 to view the activity, download slides and practice aids, and complete the post-test to earn credit. HER2-low breast cancer, currently defined as HER2 IHC 1+ or 2+/ISH-, accounts for approximately 50% of all breast cancers. While older HER2-targeted therapies did not show efficacy in HER2-low breast cancers, novel antibody–drug conjugates (ADCs) have demonstrated remarkable activity in this setting. Because of these advances and the FDA approval of the first HER2-targeting ADC for HER2-low breast cancer, there is an urgent need to rethink the approaches to HER2 testing so that patients with HER2-low breast cancer could be identified and get a chance to benefit from the new therapeutic approach. The understanding, definitions, and testing for HER2-low status continue to evolve, and many practical challenges and unanswered questions remain. This PeerView educational activity, based on a recent live symposium, explores the most cutting-edge information on HER2-low breast cancer, provides guidance on how to currently carry out HER2 testing to capture patients with HER2-low expression, and shares what’s on the horizon that may help further refine testing and treatment in this setting. Upon completion of this activity, participants should be better able to: Describe the spectrum of HER2 expression in breast cancer and the role of HER2-low expression as a new therapeutic target; Implement standard and emerging testing approaches to identify patients with HER2-low metastatic breast cancer to determine their eligibility for novel HER2-targeted therapies; Apply the latest evidence and guidelines to integrate HER2-targeted therapies into treatment plans for eligible patients with HER2-low metastatic breast cancer in the context of clinical practice or clinical trials; and Collaborate with the multidisciplinary team to ensure appropriate biomarker testing and optimal treatment selection for patients with HER2-low metastatic breast cancer.