Prevalence and Outcomes of HER2-Low Versus HER2-0 Status in Patients with Metastatic Breast Cancer.

ABSTRACT: Background: HER2-low breast cancer (HER2 immunohistochemical [IHC] score 1+, or IHC 2+ without HER2 gene amplification) is distinct from HER2-positive and HER2-0 breast cancer (IHC 0), with a differing prognosis and specific therapeutic options. The DESTINY-Breast04 trial demonstrated notable efficacy of the HER2 antibody-drug conjugate trastuzumab deruxtecan over standard chemotherapy in patients with metastatic breast cancer (MBC) defined as HER2-low. More recently, the DESTINY-Breast06 trial confirmed this benefit in hormone receptor-positive and HER2-ultralow (less than 1+, but with ≤10% of infiltrating cancer cells showing incomplete and faint/weak membrane staining) cases, prompting re-evaluation of HER2 diagnostic thresholds and treatment strategies. Methods: Eligible

SUBMITTER: Singareeka Raghavendra A 

PROVIDER: S-EPMC12838560 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature