Intermediate HER2 expression is associated with poor prognosis in estrogen receptor-positive breast cancer patients aged 55 years and older.
Breast Cancer Res Treat 2019;
179:687-697. [PMID:
31811505 DOI:
10.1007/s10549-019-05505-4]
[Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/26/2019] [Indexed: 11/24/2022]
Abstract
PURPOSE
An antibody-drug conjugate targeting HER2, DS8201, has shown clinical activity against breast cancer with low-level HER2 expression. We aimed to evaluate the prognostic impact of intermediate HER2 expression in estrogen receptor (ER)+ early breast cancer (EBC) and metastatic breast cancer (MBC) cohorts.
METHODS
We analyzed prospectively collected data from EBC and MBC cohorts at Yonsei Cancer Center. Patients with HER2 immunohistochemistry (IHC) 0 ~ 1+ were assigned to the HER2-negative group, and patients with IHC 2+ and in situ hybridization (ISH)-negativity were assigned to the HER2-intermediate group. After the exclusion of HER2 IHC 3+ or ISH+ patients, a total of 2657 EBC and 535 MBC patients were analyzed.
RESULTS
In total, 654 (24.6%) EBC and 166 (31.0%) MBC patients were classified in the HER2-intermediate group. The HER2-intermediate patients more frequently tended to have progesterone receptor (PR)-negativity and higher nuclear grade in the EBC cohort, and showed a higher proportion of patients aged ≥ 55 years compared with the HER2-negative group in the MBC cohort. The HER2-intermediate patients showed significantly poorer recurrence-free survival (RFS) compared to the HER2-negative patients in the EBC cohort (p = 0.044). Notably, intermediate HER2 expression predicted poorer RFS in EBC patients aged ≥ 55 years (hazard ratio 1.95; p = 0.042) in multivariate Cox analysis but did not affect RFS in those aged < 55 years. In line with the EBC cohort results, intermediate HER2 expression predicted poorer overall survival (OS) in MBC patients aged ≥ 55 (hazard ratio 1.45; p = 0.044) without affecting OS of those aged < 55 years.
CONCLUSION
Intermediate HER2 expression is an independent predictor of poor prognosis in both ER+ EBC and MBC patients aged ≥ 55 years. The clinical efficacy of new HER2-targeting antibody-drug conjugates needs to be validated in this high-risk subset of ER+ breast cancer patients.
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