Over 2 million new cancer cases are expected in 2006. The need for early diagnostics that improve prognosis is well documented. Studies have shown that single molecular markers are not able to accurately diagnose individuals in the clinical setting. Common protein discovery technologies lack the ability to quantitatively measure multiple biomarkers in a single assay, while newer technologies suffer from a lack of sensitivity, precision and automation. Rules-Based Medicine (RBM) has developed bead-based multiplex immunoassays for performing Multi-Analyte Profiles (MAPs) of biomarkers that has addressed these limitations. In Phase I, a quantitative, automated, 5-plex immunoassay for the rapid detection of low abundance cancer-related proteins will be developed. To further increase the breadth of the content on this platform, new methods to both develop and screen hundreds to thousands of ligand binding molecules are needed. Thus, in Phase I, an innovative approach for the rapid screening of multiple ligand binding molecules to identify those providing optimal MAP performance will be developed. During Phase II, we propose to validate the screening platform developed in Phase I by screening ligand binding molecules for an additional forty-five targets. In doing this, a 50-plex immunoassay for low abundance cancer-related proteins (i.e., an Oncology MAP) will be developed. If successful, both the screening platform and the 50-plex Oncology MAP will have commercial application as a service to pharmaceutical, biotechnological, medical and basic research communities.