NCOG-06. CASE REPORT: EXTENDED REMISSION OF HER2-POSITIVE BREAST CARCINOMA WITH BRAIN METASTASES AND LEPTOMENINGEAL DISEASE FOLLOWING INTRATHECAL AND SYSTEMIC TRASTUZUMAB

Abstract Leptomeningeal disease (LMD) in breast cancer carries a poor prognosis with median overall survival (OS) of 3-4 months. Recent series have indicated prolongation OS up to 10-13 months HER2-positive LMD treated intrathecal (IT) trastuzumab. Here we present an unprecedented long-term clinical, radiographic, and molecular response for more than 10 years on IT A 52-year-old woman presented 12/2011 newly diagnosed previously brain systemic metastases. Her initial diagnosis left intraductal carcinoma 5/2005 was bilateral mastectomy, adjuvant chemotherapy doxorubicin cyclophosphamide followed by paclitaxel trastuzumab, as well local RT. She free until 10/2009 when she headache due two metastases involving the vermis right occipital lobe. underwent resection SRS, capecitabine lapatinib. In 12/2010 received further RT posterior fossa recurrent later required gamma knife metastasis. 8/2011 developed back pain cauda equina syndrome. MRI spine revealed from T11- L2. CSF studies showed > 500 protein, 17 WBCs malignant cells consistent her primary. Both cerebellar metastasis spinal fluid over-expression amplification HER2neu. completed lower spine, 1/2012 began trastuzumab continuation There progressive 2/2012 prompting escalation dosing addition topotecan 10/2019, rare switched cytarabine while continuing now durable remission ever since. The low burden aggressive therapeutic approach, including combined radiation therapy may explain exceptional survival.