Case Report: Effective Treatment With Pyrotinib and Capecitabine in a Heavily Pretreated Locally Advanced Breast Cancer Harboring Both HER2 Overexpression and Mutant

• DOI: 10.3389/fonc.2021.715554
• Publication Date: 2021-10-14T07:44:47Z
• Authors: Zhichao Gao; Junnan Xu; Yan Wang; Jie Wu; Tao Sun
• Keywords: HER2 positive; 03 medical and health sciences; breast cancer; 0302 clinical medicine; Oncology; pyrotinib; L775S; Neoplasms. Tumors. Oncology. Including cancer and carcinogens; ERBB2 mutant; RC254-282; 3. Good health

The prognosis for female patients with locally advanced breast cancer (LABC) has improved the emergence of novel drugs, especially those who have HER2 overexpression or ERBB-2 amplification. Trastuzumab-based regimen been paradigm in guidelines as first-line therapy, whereas many got progressive disease after several cycles treatment rapidly progress because primary resistance. Point mutations ERBB2 gene occur both HER2-amplication and non-amplification patients, a 2% ratio cohort 1.48% amplication population. acquired mutation substantially raised to 16.7%–17.7% prior trastuzumab treatment. may be critical reason resistance progression among treated anti-HER2 monoclonal dual antibodies pertuzumab, tyrosine-kinase inhibitor. L755S V842I indicates trastuzumab, while that K753I lapatinib; these maybe sensitive pan-HER inhibitors. A 48-year woman diagnosed HER2-positive LABC developed three lines cross-line partial response (PR) best response. tissue was performed by next-generation sequencing (NGS), results discovered gene. Then, she received effective pyrotinib plus capecitabine underwent mastectomy six combined PR. Subsequently, performed, took 1 year monotherapy another adjuvant therapy achieved long-term clinical benefit. In conclusion, is potential neoadjuvant agent are heavily pretreated harbor amplification mutant cancer.