Safety and feasibility of intrathecal pembrolizumab infusion in refractory triple negative breast cancer with leptomeningeal disease: A case report

Leptomeningeal disease remains a marker of poor prognosis for patients with metastatic spread of solid tumors. Treatment options are limited and often poorly tolerated. Here we report a case of the first in human intrathecal administration of the PD-1 inhibitor pembrolizumab in a patient with metastatic ER/PR/HER2 negative breast cancer with leptomeningeal disease and otherwise well controlled systemic disease. This report demonstrates that the intrathecal administration of pembrolizumab is feasible and safe within the dose tested and supports the further study of intrathecal immune therapy for the treatment of leptomeningeal disease.