Intrathecal Trastuzumab for Meningeal Carcinomatosis Secondary to HER2-Overexpressing Breast Cancer

We report a 57-year-old woman with left breast cancer with lung, liver, and leptomeningeal metastasis. She received methotrexate (MTX) intrathecal injection for initial therapy, but neutropenia occurred and her neurological symptoms improved only mildly. She received intrathecal trastuzumab of 20 mg bi-weekly, and neurological symptoms improved gradually, especially dysphagia and consciousness. However, neurological symptoms worsened two months later. Intrathecal trastuzumab of 85~100 mg was given weekly, and neurological symptoms improved again. No obvious side effect was observed, and persistence of tumor-negative CSF cytology was noted after that. We also review the literature regarding intrathecal trastuzumab for leptomeningeal carcinomatosis.