Abstract
BACKGROUND: Breast cancer brain metastasis (BCBM) is an advanced breast disease that is difficult to treat and is associated with a high risk of death. Patient prognosis is usually poor, with reduced quality of life. In this context, we report the case of a patient with HER-2-positive BCBM treated with a macromolecular mAb (inetetamab) combined with a small molecule tyrosine kinase inhibitor (TKI). CASE SUMMARY: The patient was a 58-year-old woman with a 12-year history of type 2 diabetes. She was compliant with regular insulin treatment and had good blood glucose control. The patient was diagnosed with invasive carcinoma of the right breast (T3N1M0 stage IIIa, HER2-positive type) through aspiration biopsy of the ipsilateral breast due to the discovery of a breast tumor in February 2019. Immunohistochemistry showed ER (-), PR (-), HER-2 (3+), and Ki-67 (55-60%+). Preoperative neoadjuvant chemotherapy, i.e., the AC-TH regimen (epirubicin, cyclophosphamide, docetaxel-paclitaxel, and trastuzumab), was administered for 8 cycles. She underwent modified radical mastectomy of the right breast in November 2019 and received tocilizumab targeted therapy for 1 year. Brain metastasis was found 9 mo after surgery. She underwent brain metastasectomy in August 2020. Immunohistochemistry showed ER (-) and PR. (-), HER-2 (3+), and Ki-67 (10-20%+). In November 2020, the patient experienced headache symptoms. After an examination, tumor recurrence in the original surgical region of the brain was observed, and the patient was treated with inetetamab, pyrotinib, and capecitabine. Whole-brain radiotherapy was recommended. The patient and her family refused radiotherapy for personal reasons. In September 2021, a routine examination revealed that the brain tumor was considerably larger. The original systemic treatment was continued and combined with intensity-modulated radiation therapy for brain metastases, followed by regular hospitalization and routine examinations. The patient's condition is generally stable, and she has a relatively high quality of life. This case report demonstrates that in patients with BCBM and resistance to trastuzumab, inetetamab combined with pyrotinib and chemotherapy can prolong survival. CONCLUSION: Inetetamab combined with small molecule TKI drugs, chemotherapy and radiation may be an effective regimen for maintaining stable disease in patients with BCBM.