Analytical Validation and Clinical Sensitivity of the Belay Summit Assay for the Detection of DNA Variants in Cerebrospinal Fluid of Primary and Metastatic Central Nervous System Cancer

Abstract

In contrast to most solid tumors, cancers of the central nervous system (CNS) pose a unique challenge for effective detection and tracking via plasma because of the blood-brain barrier. Informed diagnosis of primary and metastatic CNS tumors can be facilitated using a liquid biopsy assay that evaluates tumor-derived DNA from the cerebrospinal fluid (CSF), potentially increasing the efficacy of diagnosis and reducing the uncertainty and morbidities associated with the current standard of care that involves neurosurgical procedures. The Belay Summit assay involves tumor-derived DNA–based genomic profiling of CSF to inform diagnosis of CNS tumors. The analytical sensitivity of Summit for single-nucleotide/multinucleotide variants and insertions/deletions is 96% at a 95% limit of detection of 0.30% variant allele fraction. Analytical sensitivity for chromosomal arm-level aneuploidy is 91% at abs(log2r) of 0.09 limit of detection. Clinical sensitivity across a cohort of 124 specimens, including primary and metastatic CNS tumors, was demonstrated to be 90% with a specificity of 95%, supporting the potential for positive clinical utility. These results demonstrate that the Belay Summit assay can accurately and reproducibly be used to inform the diagnosis of primary and metastatic CNS tumors using CSF.