Abstract
CNSide is a platform that analyzes Cerebrospinal Fluid (CSF) of patients with solid tumors having Leptomeningeal Disease for presence of tumor cells (CSF-TCs) and expression of different biomarkers via Fluorescent In Situ Hybridization (FISH), Next-Generation Sequencing (NGS) and Immunocytochemistry (ICC). CNSide was offered as a commercial test in a CAP accredited CLIA certified Laboratory and ordered at each physician’s discretion. Retrospective analysis of test results between January 2020 and October 2022 showed that the test was ordered by 19 physicians from 5 unique health systems totaling 613 tests on 218 individual patients. Of these, 162 (74.3%) were female; ages ranged from 19-99 years with a median age of 58. A range of cancer pathologies were sent for CNSide analysis, of which breast (n=105) and lung (n=65) were most common. CSF-TCs were detected in 67% (412/613) samples of which 66% (195/294) were from breast cancer patients and 76% (175/229) from lung cancer patients. In lung cancer patients, ALK was detected in 14% (17/118) and CMET in 61% (78/128). In breast cancer patients, HER2 was detected in 39% (65/168) patients, ER in 26% (44/168) and PR in 4% (5/120). Furthermore, 73% (16/22) lung cancer patients had HER positive CSF. Tumor cell detection with CNSide was more frequently seen than positive cytology and provided a more reliable quantitative measure of CNS malignant disease. This data shows that CNSide is viable from a feasibility perspective across many different tumor types. Furthermore, it is scalable and detects clinically relevant biomarkers. Analysis of the prospective FORESEE clinical trial to determine the impact of CNSide on clinical decisions is ongoing.