Direct Monitoring of Fucosylated Glycopeptides of Alpha-Fetoprotein in Human Serum for Early Hepatocellular Carcinoma by Liquid Chromatography–Tandem Mass Spectrometry with Immunoprecipitation

Purpose: Alpha-fetoprotein (AFP) is a widely used serological marker that is associated with hepatocellular carcinoma (HCC). Although the level of AFP is increased in HCC, its sensitivity for diagnosis is poor because AFP levels are also increased in liver diseases. Changes in glycoform, especially fucosylation, have been reported to be associated with the development of HCC. Experimental design: The authors introduce the monitoring of fucosylated glycopeptides by liquid chromatography (LC)-mass spectrometry (MS) combined with immunoprecipitation, where glycan-cleaved fragments with an amino acid sequence are used as transitions. Furthermore, neuraminidase for desialylation is useful to improve the MS detection limit (limit of detection [LOD] <2 ng mL ⁻¹ ) in 0.1 μL of serum. Results: The performance of the relative percentage of fucosylated AFP (AFP-fuc%) for differentiating between early HCC and cirrhosis is better than that of serum AFP levels as indicated by a greater area under the receiver operator characteristic curve (area under the curve = 0.962 vs. 0.628) and sensitivity (92.3% vs. 53.9%), respectively. Furthermore, the inter- and intraday repeatability of AFP-fuc% in serum is less than 2.1%. Conclusions and clinical relevance: These findings suggest that glycopeptide-based LC-MS/MS is a promising method and that AFP-fuc% is a clinically useful parameter for differentiating between early HCC and liver cirrhosis.