Plus Therapeutics, Inc. announced a multi-year agreement to employ Biocept's cerebrospinal fluid (CSF) assay CNSide1 in Plus Therapeutics' ReSPECT-LM Phase 1/2a dose-escalation clinical trial of Rhenium-186 NanoLiposome (186RNL) for the treatment of patients with leptomeningeal metastases (LM), which is cancer in the membranes that surround the brain and spinal cord. CNSide is an assay based on Biocept's proprietary quantitative tumor cell capture method paired with advanced digital imaging and molecular markers used to detect, characterize and quantify tumor cells in CSF of patients with a variety of solid organ carcinomas and suspected LM, particularly breast and lung cancer which are leading causes of LM. CNSide provides a robust quantitative method to evaluate tumor status and response to treatment compared to conventional CSF cytology or radiologic monitoring.