
==== Front
Neurooncol Adv
Neurooncol Adv
noa
Neuro-Oncology Advances
2632-2498
Oxford University Press US

10.1093/noajnl/vdae090.016
vdae090.016
Final Category: Basic Science Leptomeningeal Disease
AcademicSubjects/MED00300
AcademicSubjects/MED00310
BSLM-05 TRASTUZUMAB DERUXTECAN IN LEPTOMENINGEAL METASTASES FROM HER2-ALTERED CANCERS
Cao Toni Stanford University, Stanford, CA, USA

Roy-O’Reilly Meaghan Stanford University, Stanford, CA, USA

Yao Lilian Stanford University, Stanford, CA, USA

Ma Qian Stanford University, Stanford, CA, USA

Xu Nova Stanford University, Stanford, CA, USA

Nagpal Seema Stanford University, Stanford, CA, USA

Rogawski David Stanford University, Stanford, CA, USA

8 2024
02 8 2024
02 8 2024
6 Suppl 1 2024 SNO/ASCO CNS Metastases Conference i6i6
© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

Abstract

Emerging data suggest that trastuzumab deruxtecan (T-DXd) is a clinically active treatment for brain metastases from HER2+ breast cancer. We aimed to characterize the activity of T-DXd in the treatment of leptomeningeal metastases (LM) from a range of HER2-altered cancers. We reviewed neuro-oncology clinic records between July 2020 and December 2023 to identify patients who received T-DXd to treat LM. Out of 14 patients, 5 had HER2+ breast cancer, 5 had HER2-low breast cancer, 2 had HER2+ gastroesophageal cancer, and 2 had HER2-mutant non-small cell lung cancer. 8/14 (57%) patients had LM diagnosis confirmed with cancer cells in CSF found by cytology or circulating tumor cell (CTC) capture. 4/5 (80%) patients with HER2+ breast LM had a partial response on MRI using the EORTC/RANO-LM Revised-Scorecard. In contrast, 0/9 (0%) patients with other tumor pathologies had radiologic response of their LM to T-DXd. Median survival of the 5 patients with HER2+ breast cancer after initiating T-DXd was 13.9 months with 2 patients alive and continuing on T-DXd at data cutoff, whereas median survival of the 9 patients with other pathologies was 4.1 months (HR 0.32, 95% CI 0.097-1.0, p=0.05). Our findings agree with other retrospective studies showing clinical activity of T-DXd in HER2+ breast LM, but caution that T-DXd may be less effective in LM caused by HER2-low breast and other HER2-altered cancers. Given the small number of patients in our study, larger prospective studies are urgently needed to better delineate which LM patients benefit from T-DXd.
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pmc
