Leptomeningeal metastases (LM) in solid tumors is difficult to diagnose and treat, and occurs when there are cancer cells in the cerebrospinal fluid (CSF)/pia and arachnoid. Current standard of care methods to diagnose or assess treatment response of LM (Clinical Evaluation, MRI and Cytology) have limited sensitivity and specificity. This creates challenges for physicians to manage LM or determine the best course of treatment. The FORESEE Study was a multi-center, prospective clinical trial evaluating a novel diagnostic platform, CNSide, that aimed to overcome these challenges. The FORESEE study enrolled patients with breast or non-Small Cell Lung Cancer (NSCLC) with suspicion of or confirmed LM. CNSide can detect and quantify tumor cells in the CSF from patients with breast cancer or NSCLC having a suspicious or confirmed LM as well as identify actionable mutations in the CSF via Fluorescent In Situ Hybridization (FISH) and next-generation sequencing. The primary end point was to determine the impact of CNSide on physician treatment decisions. Secondary endpoints included evaluating the clinical performance of CNSide vs. cytology in tumor cell detection (sensitivity, specificity, PPV and NPV). The study enrolled 40 patients (22 breast cancer and 19 NSCLC). Each patient underwent standard of care diagnostic evaluations at baseline and at three follow up timepoints through their treatment. CNSide aided clinical decision making in 93% (50/54) of the clinical decisions. At baseline, 39 patients were assessed, showing that CNSide confirmed a positive LM diagnosis in 15% (6/39), a negative LM diagnosis in 8% (3/39), progression in 15% (6/39), resolution in 15% (6/39) and no progression, or resolution in 36% (14/39) of the patients. CNSide informed the specific drug selected for treatment in 26% (10/39) patients at baseline and demonstrated clinical high utility.

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CSF Tumor Cell (CSF-TC) Detection, Quantification and Biomarker assessment helps in clinical management of breast cancer and Non-Small Cell Lung cancer patients having Leptomeningeal Disease (FORESEE Study, NCT05414123)