# Disease Evolution Monitored by Serial Cerebrospinal Fluid Liquid Biopsies in Two Cases of Recurrent Medulloblastoma

## TL;DR

This paper shows how cerebrospinal fluid liquid biopsies can track tumor evolution in two teenage patients with recurring medulloblastoma.

## Contribution

The study demonstrates the clinical utility of serial liquid biopsies in monitoring disease evolution in recurrent medulloblastoma.

## Key findings

- Serial cerebrospinal fluid liquid biopsies revealed tumor evolution over time in two patients with recurrent medulloblastoma.
- Low-pass whole genome sequencing detected copy number alterations in circulating tumor DNA.
- The approach was clinically validated and shows potential for monitoring disease progression.

## Abstract

Medulloblastoma is the most common malignant brain tumor in childhood. Initial treatment generally includes surgery, irradiation, and chemotherapy. Approximately 20–30% of patients will experience a recurrence, which portends a very poor prognosis. The current standard of care for evaluation for relapse includes radiographic surveillance with magnetic resonance imaging at regular intervals. The presence of circulating tumor DNA in the cerebrospinal fluid has been demonstrated to be a predictor of a higher risk of progression in a research setting for patients with medulloblastoma treated on a prospective single institution clinical trial. We have previously published and clinically validated a liquid-biopsy-based genetic assay utilizing low-pass whole genome sequencing to detect copy number alterations in circulating tumor DNA. Here, we present two teenage patients with posterior fossa medulloblastoma with recurrent disease who have been monitored with serial liquid biopsies showing tumor evolution over time, demonstrating the clinical utility of these approaches.