The goal of this project is to investigate the interest of the equalizing bead technology to characterize the deep CSF proteome and to use it to individualize biomarkers in carcinomatous meningitis. Carcinomatous meningitis (CM) is increasing in frequency. CM is diagnosed in 4% to 15% of patients with solid tumors. The main problem of proteomic studies, is the very wide concentration range in body fluids, of about ten orders of magnitude. Equalization bead technology using a library of combinatorial ligands provides the opportunity to dilute abundant and concentrate trace proteins. Application to urine clearly demonstrated that the hidden low concentrated proteins can be explored, individualized and identified using this technology. In a first step, amount of CSF, impact and validation of a specific prefractionation step and analysis of the dynamic range will be first performed by seldi-tof MS. When the best experimental settings will be validated, identification will be done using nano-LC FT-MS using a LTQ-FT-Orbitrap mass spectrometer to perform an in-depth characterization of the protein content of CSF, which will set up the basis for a subsequent differential proteomic study based on nanoLC-MS approaches. We will validate, in a second step, conditions providing the best sensitivity to be compatible with the amount of CSF provided by lumbar punctures. Seldi-tof MS profiling associated to identification of statistically significant proteins, as well as quantitative analysis of equalized CSF samples by ICAT labeling, will be performed to individualized and identified biomarkers for CM. The use of innovative proteomic biomarkers could be helpful as adjunctive diagnostic tests, to assess response to treatment and should provide an earlier diagnosis, supporting better efficacy of therapy.