Intrathecal Pertuzumab and Trastuzumab in Patients With New Untreated Asymptomatic or Low Symptomatic Brain Metastasis in HER2 Positive Breast Cancer

Intrathecal administration of pertuzumab and trastuzumab will occur via lumbar puncture (spinal tap) under fluoroscopic guidance by interventional radiology at Duke University Medical Center. The spinal needle will be inserted into the spinal column and 7 mL of cerebrospinal fluid (CSF) will be collected. Once the CSF is removed, the intrathecal pertuzumab and trastuzumab will be administered using aseptic technique. At certain time points the CSF will be analyzed for free cell DNA. If subjects consent, the CSF fluid will also be stored for additional future research. Patients will be treated using a 3+3 dose-escalation design. Patients will not be accrued to the next cohort (dose escalation) until at least one patient on the previous cohort has been followed for six weeks. If a dose limiting toxicity (DLT) is seen in a patient then the cohort will be expanded by an additional 3 patients to allow for 1 in 6 patients per cohort to have a DLT before dose escalation. Dose limiting toxicity will be assessed weekly during the first six weeks of the treatment. Patients will be treated weekly for the first six weeks and then every 3 weeks (q21 days). Once the maximum tolerated dose is reached, an additional 12 patients will be enrolled in the cohort at the maximum tolerated dose. The maximum number of enrolled patients is 36. Dosing is as follows: Cohort 1 - 80mg IT trastuzumab, 10mg IT pertuzumab, cohort 2 - 80mg IT trastuzumab, 20mg IT pertuzumab, cohort 3 - 80mg IT trastuzumab, 40mg IT pertuzumab, cohort 4 - 80mg IT trastuzumab, 80mg IT pertuzumab. If the lowest dose level is found to be too toxic, the trial will stop without finding a maximum tolerated dose.