GRN1005 Alone or in Combination With Trastuzumab in Breast Cancer Patients With Brain Metastases

Key Inclusion Criteria: 1. Age ≥ 18 years 2. Histologically or cytologically-documented breast cancer (HER2 status and ER/PgR status must be known) 3. Brain metastasis from breast cancer with or without prior WBRT 4. At least one radiologically-confirmed and measurable metastatic brain lesion (≥ 1.0 cm in the longest diameter) by Gd-MRI of the brain \< 14 days prior to first dose (Metastatic brain lesions previously treated with SRS may not be target or non-target lesions) 5. Patients must be neurologically stable: On stable doses of corticosteroids and anticonvulsants (not EIAEDs, including phenytoin, phenobarbitol, carbamazepine, fosphenytoin, primidone, oxcarbazepine) for ≥ 5 days prior to obtaining the baseline Gd-MRI of the brain and ≥ 5 days prior to first dose 6. KPS ≥ 70% 7. Completed WBRT for intra-cranial lesions ≥ 28 days prior to first dose Key Exclusion Criteria: 1. NCI CTCAE v4.0 Grade ≥ 2 neuropathy 2. CNS disease requiring immediate neurosurgical intervention (e.g., resection, shunt placement, etc.) 3. Known leptomeningeal disease