Because serum anti-tumor antigen antibodies increase along with activation of anti-tumor immune response, antibody levels are critical biomarker to predict the efficacy of cancer immune therapy, as well as evaluates immune-related therapeutic outcome. Aberrantly expressed tumor antigens in cancer cells recognized by the immune system varies in individuals. Although comprehensive antigen array is required for antibody detection, most antigens are unstable and aggregative properties. S-cationization techniques to solubilize denatured proteins combination with Luminex technology, Multiple S-cationized antigen beads array assay (MUSCAT-Assay) allowed sensitive antibody analysis. This technology will help cancer precision medicine.