%0 Journal Article
%T Differences in Treatment Outcomes Between Patients with HER2-Low versus HER2-Zero, Hormone Receptor-Positive Advanced-Stage Breast Cancer Treated with Ribociclib.
%A Sharaf B
%A Abu-Fares H
%A Tamimi F
%A Al-Sawajneh S
%A Salama O
%A Daoud R
%A Alhajahjeh A
%A Al-Lababidi S
%A Abdel-Razeq H
%J Breast Cancer (Dove Med Press)
%V 15
%N 0
%D 2023
%M 37533590
%F 5.088
%R 10.2147/BCTT.S415432
%X <B>UNASSIGNED: </B>Metastatic breast cancers (MBC) with no expression of human epidermal growth factor receptor-2 (HER2) are recently classified into two groups; HER2-zero [HER2-immunohistochemistry (IHC) score of 0 (IHC-0)] and HER2-low, defined as those with IHC score of 1+ or 2+ with negative in situ hybridization (ISH) assay. We investigate differences in treatment outcomes between both groups treated with endocrine therapy (ET) and the CDK4/6 inhibitor ribociclib.<BR><B>UNASSIGNED: </B>Data were retrospectively collected for patients with HR-positive+/HER2-negative MBC who received ribociclib with an aromatase inhibitor (AI) or fulvestrant and were divided into two groups: HER2-zero and HER2-low.<BR><B>UNASSIGNED: </B>A total of 257 patients, median age 48 (22-87) years, all with MBC who were treated with ET and ribociclib were enrolled. One hundred and thirty-seven (53.3%) patients had de novo MBC, and majority (n = 162, 63.0%) received ribociclib as a first-line therapy. In total, 114 (44.4%) patients had HER2-zero (IHC-0), while 143 (55.6%) others had HER2-low disease. The overall response rate (ORR) was 52.0% for the HER2-zero group compared to 39.4% for the HER2-low group, p = 0.005. The median PFS was 22.2 (95% confidence interval [CI], 19.4-NR) months for HER2-zero versus 17.3 (95% CI, 14.1-20.6) months for HER2-low, P = 0.0039. In multivariable analysis, HER2-low expression remained significant determinant of inferior PFS after adjusting for other factors, including the site of metastasis, prior chemotherapy, and the line of treatment.<BR><B>UNASSIGNED: </B>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.