Diverse monoclonal antibodies against the CA 19‐9 antigen show variation in binding specificity with consequences for clinical interpretation

Abstract

The CA 19-9 antigen is currently the best individual marker for the detection of pancreatic cancer. In order to optimize the CA 19-9 assay and to develop approaches to further improve cancer detection, it is important to understand the specificity differences between CA 19-9 antibodies and the consequential affect on biomarker performance. Antibody arrays enabled multiplexed comparisons between five different CA 19-9 antibodies used in the analysis of plasma samples from pancreatic cancer patients and controls. Major differences were observed between antibodies in their detection of particular patient samples. Glycan array analysis revealed that certain antibodies were highly specific for the canonical CA 19-9 epitope, sialyl-Lewis A, while others bound sialyl-Lewis A in addition to a related structure called sialyl-Lewis C and modification with Nue5Gc. In a much larger patient cohort we confirmed the binding of Sialyl-Lewis C glycan by one of the antibodies and showed that the broader specificity led to the detection of an increased number of cancer patients without increasing detection of pancreatitis patient samples. This work demonstrates that variation between antibody specificity for cancer-associated glycans can have significant implications for biomarker performance and highlights the value of characterizing and detecting the range of glycan structures that are elevated in cancer.

CA 19-9: handle with care

“…The only analytical method to determine the malignant nature of these elevations, which often lead to hospitalization and costly and cumbersome procedures, such as diagnostic imaging, is to assess the relationship between sialyl-Lewis a and its benign counterpart, disialyl-Lewis a , which is not elevated in malignant disease [ 21 ]. Recently, Partyka et al [ 22 ] have demonstrated, by the use of ' arrays ' with five different antibodies on samples of patients with cancer of the pancreas and with pancreatitis, significant differences between the two groups as well as on single specimens; Brought to you by | Lulea University of Technology Authenticated | 130.240.43.43 Download Date | 9/16/13 2:33 PM some antibodies are highly specific for sialyl-Lewis a, while others identify also a structure related thereto, called sialyl-Lewis c. This finding, subsequently confirmed on a larger cohort, suggests that the use of different antibodies can lead to a better sensitivity in patients with malignant disease without an increase in reactivity in the absence of said disease.…”

Glycoprotein Disease Markers and Single Protein-omics

“…Detailed characterization of the targets and validation of reagents for detection of specific carbohydrate structures are essential. A study of common antibodies to cancer antigen 19-9 (CA19-9) 1 , used in serological screening of pancreatic cancer, showed that some recognize the expected sialyl-Lewis A antigen but others cross-react with sialyl-Lewis C and Nglycolylneuraminic acid-containing epitopes (48). Table I summarizes antibodies to the important group of Lewis-type carbohydrates tested on the Consortium for Functional Glycomics arrays.…”

The Detection and Discovery of Glycan Motifs in Biological Samples Using Lectins and Antibodies: New Methods and Opportunities

“…For example, the sialyl Lewis A antigen is strongly overexpressed in pancreatic cancer, and several monoclonal antibodies are available to detect sLeA, but questions remain about whether the antibodys’ affinity to sLeA remains as high when the sLeA motif is slightly modified or presented in differing ways. An analysis of various antibodies ( Partyka, Maupin, Brand, & Haab, 2012 ) showed differences in specificity: some were highly specific—only binding sLeA—and others also bound related motifs.…”