Partial Response to Pyrotinib Plus Capecitabine in an Advanced Breast Cancer Patient with Amplification and Mutation After Anti- Treatment: A Case Report and Literature Review.

Human epidermal growth factor receptor2 () overexpression/amplification is associated with high malignancy, rapid disease progression and poor overall survival in breast cancer. The application of anti- drugs has greatly improved the survival of patients with -positive breast cancer, but drug resistance issues affect the long-term efficacy. The mutation is considered to be one of the reasons for resistance to anti- therapy, and there is currently no standard treatment. We report for the first time the detection of amplification with mutation by second-generation sequencing (NGS) in a 57-year-old hormone receptor-negative, -positive woman with advanced breast cancer who was resistant to multi-line anti- therapies. She subsequently received pyrotinib combined with capecitabine treatment and achieved partial response. The small-molecule pan- family irreversible inhibitor pyrotinib combined with capecitabine has shown a promising effect in the treatment of mutation-induced resistance, but the molecular mechanism and efficacy need to be further verified.