Evaluation of tumor marker cancer antigen 72-4 (CA 72-4) in the monitoring of metastatic or recurrent tumors of the gastrointestinal tract, lung, breast, and ovaries.

263 Background: In management of metastatic and recurrent cancers, measuring response is a constant challenge. CA72-4 is a tumor marker (TM) that has been found elevated in a variety of human adenocarcinomas, with reported sensitivities of up 50% and overall specificity of over 95%. Using the DRG TM-CA72-4 assay, we quantified the abnormality rate of TM CA72-4 compared with current FDA-approved TM in various cancers. Methods: We conducted a prospective, single center study by enrolling 96 patients between March 2013 and August 2016 with various de novo or previously diagnosed locally advanced, unresectable and/or metastatic cancers known to express CA72-4. Quantification of CA72-4 was performed according to manufacturer’s instructions using the DRG TM-CA72-4 ELISA kit, which was developed by DRG International (Germany) utilizing the CC-49 monoclonal mouse antibody directed against an epitope on the CA72-4 antigen. Positivity was calculated as greater than A) 0.8 U/mL or B) 4.0 U/mL based on systematic review of prior studies. Results: The positivity rates based on different cut-off points (0.8 U/mL vs 4 U/mL) and their corresponding FDA approved tumor markers are shown in the Table. Conclusions: Positivity rates of CA72-4 varied based on different assay cut-off levels with the highest positivity noted in the pancreatic, ovarian and colorectal carcinomas indicating a potential role for disease monitoring. [Table: see text]