Response of an ERBB2 Exon 20 Insertion Mutation Breast Cancer to Pyrotinib
Breast cancer is the most frequent malignancy among women worldwide, the incidence of which is increasing at a high rate. With the advent of next-generation sequencing, a small proportion of relapsed and refractory breast cancers could be found to harbor activating somatic mutations, making them susceptible to anti-HER2 (human epidermal growth factor receptor 2) therapies. Here, we present a case of a breast cancer patient with ERBB2 (Erb-b2 receptor tyrosine kinase 2) exon 20 insertion mutation, treated successfully with pyrotinib plus trastuzumab combined with chemotherapy. We also confirmed that pyrotinib could inhibite MAPK/ERK pathway in ERBB2 mutation cells. This case also highlights the usefulness of genomic testing in patients, which may help to expand the therapeutic options available to them.