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Tumor Discovery

CASE REPORT
Efficacy of pyrotinib and capecitabine in

recurrent breast cancer with a HER2-negative
genetic switch following systemic therapy: A

case report and literature review

2
1
2,3
Yuling Zhang , Bingfeng Chen , Jundong Wu , and Chunfa Chen *
2,3
1 Department of Medical Quality Management, Cancer Hospital of Shantou University Medical
College, Shantou, Guangdong Province, China
2 The Breast Center, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong
Province, China
3 The Research Laboratory for Breast Cancer Diagnosis and Treatment, Cancer Hospital of Shantou
University Medical College, Shantou, Guangdong Province, China

Abstract

Despite the demonstrated safety and efficacy of pyrotinib and capecitabine in
treating human epidermal growth factor receptor 2 (HER2)-positive metastatic
breast cancer, their efficacy in recurrent breast cancer in which the HER2 status has
changed to negative remains unexplored. Here, we report a case of a 38-year-old
*Corresponding author: female diagnosed with invasive ductal adenocarcinoma of the left breast, staged as
Chunfa Chen
(chenchunfa@stu.edu.cn) mcT2N0M0. Fluorescence in situ hybridization (FISH) confirmed that the tumor was
hormone receptor (HR) positive with low HER2 expression (2+) and a HER2/CEP17 ratio
Citation: Zhang Y, Chen B, Wu J,
Chen C. Efficacy of pyrotinib and of 3.56. Following neoadjuvant targeted therapy and chemotherapy, she underwent a
capecitabine in recurrent breast modified radical mastectomy. Post-surgical histopathological examination revealed a
cancer with a HER2-negative non-pathological complete response, classified as ypT1cypN1M0. The tumor remained
genetic switch following systemic
therapy: A case report and HR positive with low HER2 expression (2+), but the FISH result was negative (HER2/
literature review. Tumor Discov. CEP17 ratio of 1.65). For 1 year, she was administered dual-targeted therapy with
2025;4(1):113-119. goserelin and exemestane. Sequential therapy with neratinib was initiated; however,
doi: 10.36922/td.4093
it was discontinued due to grade IV diarrhea. Despite ongoing endocrine therapy, she
Received: June 30, 2024 experienced tumor recurrence on the left chest wall. A biopsy of the recurrent lesion
Revised: August 3, 2024 revealed it to be HR positive with low HER2 expression (2+) and a negative FISH result
(HER2/CEP17 ratio of 1.33). The recurrent lesion responded to combination therapy
Accepted: August 19, 2024
consisting of pyrotinib and capecitabine, with tolerable adverse events. This case
Published online: October 8, 2024 highlights the potential advantages of combining pyrotinib and capecitabine when
Copyright: © 2024 Author(s). the HER2 status changes to negative following systemic therapy.
This is an Open-Access article
distributed under the terms of the
Creative Commons Attribution Keywords: Breast cancer; Human epidermal growth factor receptor 2 change; Low
License, permitting distribution, human epidermal growth factor receptor 2 expression; Pyrotinib; Case report
and reproduction in any medium,
provided the original work is
properly cited.
Publisher’s Note: AccScience
Publishing remains neutral with 1. Background
regard to jurisdictional claims in
published maps and institutional Human epidermal growth factor receptor 2 (HER2) status discordance is prevalent in
affiliations. breast cancer, reflecting its heterogeneity. Approximately 15% – 22% of patients exhibit

Volume 4 Issue 1 (2025) 113 doi: 10.36922/td.4093