Intrathecal Trastuzumab for Leptomeningeal Metastases in HER2+ Breast Cancer

Inclusion Criteria: ELIGIBILITY CRITERIA * HER2 positive (IHC 3+ and/or FISH positive) breast cancer patients with leptomeningeal metastases by MRI or CSF (if MRI is negative). o Review will be performed for cases not reviewed at Northwestern for confirmation, but will not preclude patients from entering the trial (pathology report is sufficient for registration). * Patients can have concomitant brain metastases as long as they do not require active treatment or have been treated. * Patients with leptomeningeal disease from ependymomas, gliomas, and medulloblastoma will be eligible for phase I * Life expectancy \> 8 weeks * Normal renal (creatinine \< 1.5 ULN), liver (bilirubin \< 1.5 x ULN, transaminases \< 3.0 x ULN, except in known hepatic metastasis, wherein may be \< 5 x ULN) and blood counts (WBC \> 3.0, Neutrophils \> 1500, platelets \>100 000, Hemoglobin \> 10). * LVEF \> 50% * KPS \> 50 * Age \> 18 years * Cannot be on systemic agents (chemotherapy) that have CNS penetration unless they develop leptomeningeal metastases while on these agent(s) and have controlled systemic disease. May continue on IV trastuzumab, lapatinib or hormonal agents if controlling systemic disease and developed LM while on therapy. Patients requiring systemic chemotherapy are eligible but will not be able to start treatment until after the first assessment by imaging and cytology. * Patients may need a CSF flow study at the discretion of the treating principal investigator. If a spinal b…