Differences in Treatment Outcomes Between Patients with HER2-Low versus HER2-Zero, Hormone Receptor-Positive Advanced-Stage Breast Cancer Treated with Ribociclib.

In patients with MBC treated with ET and ribociclib, level of HER2 negativity may affect treatment outcomes; patients with HER2-zero had better response rate and PFS compared to those with HER2-low disease. These findings, if confirmed in larger studies, may help oncologists select patients with HER2-low for better treatment options.