Abstract LB097: Sensitive detection of central nervous system tumors using a sequencing based cerebrospinal fluid test

Abstract The current approach to diagnosing and monitoring tumors of the central nervous system relies almost exclusively on radiographic imaging and neurosurgical procedures. Cerebrospinal fluid (CSF) is appealing for diagnosis because it is already part of the standard of care for the diagnosis or management of several types of CNS disease, including cancer, and the tumor DNA is more highly concentrated inside the blood brain barrier than in plasma or other bodily fluids. Even though cytology is widely used, sensitivity remains low ranging from 2% to 50%, depending on cancer type. We report an analytic technique that efficiently introduces identical molecular barcodes to both strands of CSF template DNA molecules for the identification of cancer specific somatic mutations and copy number alterations. We apply this approach to 126 CSF samples obtained from individuals with known primary or metastatic tumors involving the brain and 36 CSF samples obtained from individuals with non-neoplastic neurological conditions such as multiple sclerosis and another neurologic conditions. We correctly detect 91% of cancers at a specificity of 94. 5%. In cases (n=20) where standard of care cytology was available, cytology detected 25% of cancers while our molecular assay detected 90%. Our approach has the capacity to be used in combination with other clinical, radiologic, and laboratory-based data to inform the diagnosis and management of patients with suspected cancers of the brain. Positives n= Sensitivity GBM 42 46 91. 3% Lymphoma 22 24 91. 7% Medulloblastoma 14 16 87. 5% Metastases 37 40 92. 5% Citation Format: Christopher B. Douville, Chetan Bettegowda. Sensitive detection of central nervous system tumors using a sequencing based cerebrospinal fluid test abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr LB097.