Abstract Details

Title Safety and Feasibility of Intrathecal Pembrolizumab Infusion in Refractory Triple Negative Breast Cancer with Leptomeningeal Disease

Topic Neuro-oncology

Presentation(s) Neuro-oncology Posters (7:00 AM-5:00 PM)

Poster/Presentation
Number 017

Objective To determine the safety and feasibility of intrathecal Pembrolizumab use in triple negative breast cancer with leptomeningeal disease

Background Leptomeningeal disease remains a marker of poor prognosis for patients with metastatic spread of solid tumors. Within breast cancer, patients with a triple negative signature display the worst outcome with a median overall survival of 2.2 months from the time of leptomeningeal diagnosis. Treatment options are limited and often poorly tolerated. While systemic immune therapy with PD-L1 inhibitors has increasing use in solid tumors, the response of systemic infusions on CNS disease remains limited. To date, it remains unknown whether direct intrathecal administration of immune therapy can be delivered safely and effectively, and whether this will result in meaningful clinical response.

Design/Methods N/A

Results Here we report a case of the first in man intrathecal administration of the PD-L1 inhibitor pembrolizumab in a patient with metastatic ER/PR/HER2 negative breast cancer with leptomeningeal disease and otherwise well controlled systemic disease. This patient received two IT infusions over the course of three weeks and displayed no acute or delayed infusion reactions, and there were no observed side effects directly attributable to the therapy.

Conclusions This report demonstrates that the intrathecal administration of PD-L1 inhibitors is feasible and safe within the dose tested and supports the further study of intrathecal immune therapy for the treatment of leptomeningeal disease in triple negative breast cancer. Moreover, this finding may have the potential for extrapolation across leptomeningeal disease from all solid tumors and further studies are warranted to evaluate for safety and efficacy in this setting.

Authors/Disclosures
Shannon Fortin Ensign, MD, PhD (Mayo Clinic) PRESENTER	Dr. Fortin Ensign has nothing to disclose.
	No disclosure on file
	No disclosure on file
Maciej M. Mrugala, MD, PhD, MPH, FAAN (Mayo Clinic)	Dr. Mrugala has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Veevo Biomedicines Inc. Dr. Mrugala has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Arbor Pharmaceuticals. Dr. Mrugala has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Astra-Zeneca. Dr. Mrugala has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck. Dr. Mrugala has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Kyiatec . The institution of Dr. Mrugala has received research support from Arbor Pharmaceuticals. Dr. Mrugala has a non-compensated relationship as a Program Director with Society for Neuro-Oncology that is relevant to AAN interests or activities.

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