Development of an automated chemiluminescent immunoassay for cancer antigen 72–4 and the evaluation of its analytical performance

OBJECTIVES: Cancer antigen (CA) 72–4 assay is widely used for monitoring gastric and ovarian cancers. The antigen is a mucin-like, tumor-associated glycoprotein known as TAG-72. It has been identified and characterized using two different monoclonal antibodies, CC49 and B72.3, which recognize its glycochain epitopes, Galβ(1–3) sialyl-Tn and sialyl-Tn antigens, respectively. This study describes the quantitative analytical performance of a newly developed CA 72–4 assay, ARCHITECT CA 72–4. DESIGN: and Methods: The ARCHITECT CA 72–4 assay was developed using the ARCHITECT i2000SRs and three ARCHITECT i1000SRs. The assay performance was evaluated based on guidance from CLSI (Clinical and Laboratory Standards Institute) and correlation against Elecsys CA 72–4. RESULTS: In the total precision study, the minimum coefficient of variation (CV) for Control/Panel samples over 4 U/mL was 1.1%. The measuring interval was from 0.95 to 200 U/mL with good linearity; and limits of blank (LoB), detection (LoD), and quantitation (LoQ) were 0.09, 0.18, and 0.95 U/mL, respectively. High dose hook effect; differences among specimen tube types; and interference of common drugs, potential cross-reactants, and endogenous substances were not observed. Significantly, this assay has high biotin tolerance at 4875 mg/mL and correlates well with the Elecys CA 72–4 assay (correlation coefficient: 0.95). CONCLUSIONS: ARCHITECT CA 72–4 is a highly sensitive and precise assay for CA 72-4 measurement in human sera and plasma.