Fig. 5: CSF ctDNA reveals the evolving genomic landscape at relapse of patients with MB.

Longitudinal monitoring of two paediatric patients with MB that relapsed and died from the disease: a–c MB8 and d–f MB5. a, d Clinical course indicating intervention for hydrocephalus, tumour surgery, treatment protocol, radiologic images (MRI), tumour size or residual disease, and patient samples obtained. Yellow arrows within the MRIs indicate the tumours at relapse. b, e Heatmap representing mutations and VAFs (%) identified from the WES of tumour DNA, CSF1 and CSF2 cfDNA samples. VAFs <10% were annotated. For patient MB8, a representative list of mutations (with a high/moderate impact or identified as drivers/predicted drivers by the Cancer Genome Interpreter) is shown. The first heatmap is for mutations detected in both tumour and CSF (n = 61) and the second one for private mutations (n = 53). Blue arrows indicate the mutations selected for further validation. c, f Relevant MB CNV identified were indicated in red for amplification (log₂ > 1) or blue for deletion (log₂ < −1). Definition of symbols and acronyms: not detected (ND), day (d), external ventricular drain (EVD), endoscopic third ventriculocisternostomy (ETV), residual (R) disease status: >1.5 cm² (+), <1.5 cm² (−), chemotherapy (CXT) and radiotherapy (RT).