Immune response and its correlation with the disease activity in patients with advanced colorectal cancer (aCRC): Results from a prospective observational study.

471 Background: Currently limited biomarkers are available to monitor disease status in cancer patients. Although host factors are critical in regulating cancer, the role of immune responses in aCRC is less clear. A predominant T helper 1 (Th1) response may be more effective to contain cancer than one with a substantial Th2 component. The Th1/Th2 phenotype can be inferred from relative prevalence of IgG isotypes among anti-cancer antibodies and may provide an innovative way to assess disease activity. The study aims to develop an ELISA assay to monitor IgG1:IgG2 and its utility in predicting disease status in aCRC. Methods: A validated ELISA assay (Bertech Pharma) utilizing CRC cell lines was developed to measure IgG1 (Th2) and IgG2 (Th1) levels. A sample size of 44 (24 CRC and 20 healthy control [HC]) was estimated to achieve 80% power and α error of 0.05 assuming that the assay correctly detect CRC specific antibody in > 80% cases. The IgG1:IgG2 was compared between/within groups with HC and aCRC. Resul...