Pyrotinib in the treatment of human epidermal growth factor receptor 2-positive metastatic breast cancer: A case report.

Rationale: Pyrotinib is a novel dual pan-ErbB receptor tyrosine kinase inhibitor, approved for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC). However, there was still limited information regarding specific effect of pyrotinib on HER2-positive MBC patients with phosphoinositol-3 kinase mutation. Patient concerns: A 63-year-old woman accidentally discovered a left breast lesion. The breast cancer was diagnosed by biopsy of breast lesion and postoperative pathological examination in March, 2017. The patient was presented with HER2-positive (3+), invasive carcinoma of the left breast with lymph nodes and lung nodules metastasis, and the clinical stage was T4N2M1. However, the lesion continued to aggressive disease progression with the treatment of trastuzumab plus multiple chemotherapy regimens and traditional Chinese medicine. Diagnoses: The woman was diagnosed with invasive carcinoma of the left breast and lymph nodes and lung nodules metastasis. Interventions: The patient received 6 cycles of pyrotinib in combination with capecitabine regularly. Outcomes: Progression free survival was more than 6 months, and the patient's efficacy evaluation was partial remission. Lessons: Our clinical observations demonstrated that pyrotinib may be an effective treatment for patients with HER2-positive MBC.