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Elia Seguí: Honored to Present Our Work at The 2025 SNO/ASCO CNS Metastases Conference

Elia Seguí/clinicbarcelona.org

Aug 16, 2025, 07:42

Elia Seguí: Honored to Present Our Work at The 2025 SNO/ASCO CNS Metastases Conference

Elia Seguí, Breast Cancer Medical Oncologist and Translational Researcher at Dana-Farber Cancer Institute, shared a post on LinkedIn:

“Honored to present our work at the 2025 Society for Neuro-Oncology/American Society of Clinical Oncology (ASCO) CNS Metastases Conference, where it received the Basic Science / Pre-Clinical Award.

Up to half of patients with HER2+ metastatic breast cancer develop brain metastases, leading to major morbidity and reduced survival. Yet, genomic profiling of these tumors remains limited.
Plasma-ctDNA has low sensitivity for brain disease, but CSF-ctDNA may better reflect the genomic landscape of CNS tumors and serve as a more accurate biomarker.
We analyzed paired plasma and CSF samples collected in a phase II trial (NCT03765983) of paxalisib (a brain-penetrant PI3K/mTOR inhibitor) plus trastuzumab in HER2+ active brain metastases. Ultra-low-pass whole-genome sequencing (ULP-WGS) and whole-exome sequencing (WES) were performed.
Genomic alterations were consistent with HER2+ MBC, including ERBB2 amplification, TP53, and PIK3CA/PTEN mutations.
Tumor fraction (TF) was consistently higher in CSF than plasma (median 0.56 vs 0.02), and CSF TF changes correlated with CNS tumor changes.
The only patient with sustained clinical benefit (>24 weeks SD) showed the largest TF decline and marked CSF clonal evolution (|△CCF|>0.20).
Phylogenetic analysis in one patient revealed shared truncal mutations in plasma and CSF, with CSF-specific subclones detected at low clonality in plasma.

Take home: CSF-ctDNA may better capture tumor genomics and treatment response than plasma-ctDNA in HER2+ brain metastases.

So thankful to the team, mentors, and patients who made this happen!”

Elia Seguí: Honored to Present Our Work at The 2025 SNO/ASCO CNS Metastases Conference