Haptoglobin phenotype is a critical factor in the use of fucosylated haptoglobin for pancreatic cancer diagnosis.

Fucosylation is one of the most important glycosylations involved in cancer and inflammation. Many studies have reported significant increases in serum fucosylated haptoglobin (Fuc-Hpt) in a variety of cancer patients. In this study, we measured Fuc-Hpt using a lectin-antibody enzyme-linked immunosorbent assay (ELISA) or a novel ELISA system that used a glycan antibody for Fuc-Hpt. Hpt is known to be divided into three phenotypes (Hpt1-1, Hpt2-1, and Hpt2-2), depending on its genetic background. Normal levels of serum Hpt are different in each Hpt phenotype and these phenotypes are associated with the incidence of several human diseases. Here, we investigated how Hpt phenotype affected measurements of Fuc-Hpt, using two kinds of ELISA. Interestingly, we found that serum Fuc-Hpt levels were dramatically lower in the Hpt1-1 phenotype for both types of ELISA. For Hpt2-1 and Hpt2-2, we observed significantly increased serum Fuc-Hpt levels in patients with pancreatic cancer. When cases of the Hpt1-1 phenotype were depleted, our receiver operating characteristic (ROC) curve analyses showed that the area under the curve (AUC) value for pancreatic cancer diagnosis increased in each ELISA. Taken together, our results indicate that Hpt phenotype is a critical for the clinical application of Fuc-Hpt as a cancer biomarker.