Liquid-phase binding assay of alpha-fetoprotein using a sulfated antibody for bound/free separation

Quantitative mass spectrometric analysis of hepatocellular carcinoma biomarker alpha-fetoprotein

Serum alpha-fetoprotein (AFP) has been used as a marker for the diagnosis of hepatocellular carcinoma (HCC) and its core fucosylation is associated with the early stage of HCC. However, current methods for the detection of AFP with core fucose are not highly accurate for early diagnosis. In this study, we established an enzyme-assisted mass spectrometric method for the quantitative analysis of AFP/core fucose with high specificity and sensitivity. We employed endoglycosidase treatment of AFP to improve the biomarker analysis. The accuracy and precision are within the US FDA-suggested value, and a good linearity (r2 = 0.9930) and a detection limit of 15.6 ng mL-1 can be achieved.

Highly sensitive Lens culinaris agglutinin-reactive fraction of α-fetoprotein is a predictive marker for hepatocarcinogenesis in long-term observation of patients with chronic liver disease

Highly sensitive Lens culinaris agglutinin-reactive fraction of α-fetoprotein (hs-AFP-L3) is a specific marker for hepatocellular carcinoma (HCC) and has been reliable in cases with a low serum α-fetoprotein (AFP) level. However, the biomarkers that contribute to hepatocarcinogenesis during the long-term observation are not yet clear. The present study reported the clinical utility of hs-AFP-L3 in the long-term observation of patients with chronic liver disease. The subjects were 106 patients with chronic liver disease without HCC or a history of HCC treatment and who had been followed for >12 months. hs-AFP-L3 was measured using cryopreserved serum. The factors contributing to hepatocarcinogenesis were examined using univariate and multivariate analyses. The median observation period was 88 months (15-132 months). The cumulative incidence of HCC was 10.5% at 5 years and 19.6% at 10 years. The univariate analysis revealed that age ≥55 years old, platelet count ≤13.1x10⁴/µl, hyaluronic acid ≥80.8 ng/ml, alanine transaminase ≥47 U/l, AFP ≥6.3 ng/ml, hs-AFP-L3 ≥3.5% and des-γ-carboxy prothrombin (DCP) ≥25 mAU/ml were significant factors. In the multivariate analysis, platelet count ≤13.1x10⁴/µl [hazard ratio (HR), 4.966; 95% confidence interval (CI), 1.597-15.437; P=0.006] and hs-AFP-L3 ≥3.5% (HR, 5.450; 95% CI, 1.522-19.512; P=0.009) were extracted as significant factors contributing to hepatocarcinogenesis. In addition, for cases with AFP <20 ng/ml, a multivariate analysis revealed that hs-AFP-L3 ≥4.9% (HR, 11.608; 95% CI, 2.422-55.629; P=0.002) and DCP ≥25 mAU/ml (HR, 3.936; 95% CI, 1.088-14.231; P=0.037) were significant factors contributing to hepatocarcinogenesis. hs-AFP-L3 is a useful marker for predicting hepatocarcinogenesis in the long-term observation of patients with chronic liver disease.

A Chemiluminescent Protein Microarray Method for Determining the Seroglycoid Fucosylation Index

The Lens culinaris agglutinin-reactive fraction of AFP (AFP-L3) is widely used to screen for hepatocellular carcinoma (HCC) in Japan and China. We developed a chemiluminescent protein microarray for determining the AFP-L3/AFP index (the ratio of AFP-L3 to total AFP, AFP-L3%) by fixing AFP-specific antibodies and Lens culinaris lectin on aldehyde-coated glass slides. Serum samples were tested for AFP using an enzyme-linked immunosorbent assay (ELISA) to validate the microarray. AFP-L3 was detected using Hotgen Biotech glycosyl capture spin column pretreatment technology and ELISA. When the AFP cut-off value was set to 20 ng/ml, the protein microarray displayed 89.74% sensitivity and 100% specificity for HCC diagnosis, and the ELISA displayed 87.17% sensitivity and 100% specificity. When the AFP-L3% cut-off value was set to 0.1, the protein microarray displayed 56.41% sensitivity and 100% specificity for HCC diagnosis, and the ELISA displayed 53.84% sensitivity and 100% specificity. The ROC curve for the HCC diagnosis showed that the AFP area under the ROC curve (AUC = 0.996; 95% CI: 0.986-1.005) was much higher than that of AFP-L3 (AUC = 0.857; 95% CI: 0.769-0.94) and AFP-L3% (AUC = 0.827; CI: 0.730-0.924). The microarray assay used in this study is a highly sensitive, accurate, and efficient assay for the determination of the AFP-L3%.

Increase of fucosylated alpha-fetoprotein fraction at the onset of autoimmune hepatitis and acute liver failure

AIM

Increased serum α-fetoprotein (AFP) has been associated with a good prognosis following acute liver failure (ALF), but the levels of the fucosylated fraction of AFP (Lens culinaris agglutinin-reactive fraction of AFP [AFP-L3]) following acute liver injury remain unknown. The aim of the present study was to investigate the clinical significance of AFP and AFP-L3 in patients with acute liver injury.

METHODS

We investigated the serum levels of AFP and highly sensitive AFP-L3% in 27 patients with acute-onset autoimmune hepatitis (AIH), 28 patients with acute hepatitis (AH) and 22 patients with ALF at the onset using a highly sensitive immunoassay (micro-total analysis system).

RESULTS

The serum AFP levels were increased in patients with AIH, AH and ALF, but the levels did not significantly differ among them. However, the mean AFP-L3% level was significantly higher in patients with AIH than in patients with AH (P = 0.0039). Moreover, significantly more patients with AIH demonstrated AFP-L3 positivity (≥10%) when compared with patients with AH (P = 0.014). Although the percentage of AFP-L3 positivity increased with AFP levels, at low serum AFP levels (<10 ng/mL), significantly more patients with AIH demonstrated AFP-L3 positivity than did patients with AH (P = 0.024) or ALF (P = 0.038).

CONCLUSION

We demonstrated for the first time that highly sensitive AFP-L3% levels were increased at the onset of AIH. The mechanism underlying the increase in AFP-L3 remains to be elucidated, but this finding may reflect an alteration of the glycosylation such as hyperfucosylation, which can influence the modifications of self-antigens in hepatocytes.

Development of a highly sensitive glycan microarray for quantifying AFP-L3 for early prediction of hepatitis B virus-related hepatocellular carcinoma. PLoS One. 2014;9:e99959. [PMID: 24927126 PMCID: PMC4057280 DOI: 10.1371/journal.pone.0099959]

The α-fetoprotein fraction L3 (AFP-L3), which is synthesized by malignant cells and incorporates a fucosylated oligosaccharide, has been investigated as a diagnostic and prognostic marker for hepatocellular carcinoma (HCC). Quantification of AFP-L3 by conventional enzyme-linked immunosorbent assay (ELISA) has not always produced reliable results for serum samples with low AFP, and thus we evaluated the clinical utility of quantifying AFP-L3 using a new and highly sensitive glycan microarray assay. Sera from 9 patients with chronic hepatitis B and 32 patients with hepatitis B virus (HBV)-related HCC were tested for AFP-L3 level using the glycan microarray. Additionally, we compared receiver operator characteristic curves for the ELISA and glycan microarray methods for determination of the AFP-L3: AFP-L1 ratio in patient samples. This ratio was calculated for 8 HCC patients who underwent transarterial embolization therapy pre- or post-treatment with AFP-L3. Glycan microarrays showed that the AFP-L3 ratio of HBV-related HCC patients was significantly higher than that measured for chronic hepatitis B patients. Overall parameters for estimating AFP-L3% in HCC samples were as follows: sensitivity, 53.13%; specificity, 88.89%; and area under the curve, 0.75. The elevated AFP-L3% in the 8 patients with HBV-related HCC was strongly associated with HCC progression. Following one month of transarterial embolization therapy, the relative mean AFP-L3% decreased significantly. In addition, we compared Fut8 gene expression between paired tumor and non-tumor tissues from 24 patients with HBV-related HCC. The Fut8 mRNA expression was significantly increased in tumorous tissues in these patients than that in non-tumor tissue controls. Higher expression of Fut8 mRNA in tumorous tissues in these patients was associated with poor differentiation than well and moderate differentiation. Our results describe a new glycan microarray for the sensitive and rapid quantification of fucosylated AFP; this method is potentially applicable to screening changes in AFP-L3 level for assessment of HCC progression.

Value of highly sensitive fucosylated fraction of alpha-fetoprotein for prediction of hepatocellular carcinoma recurrence after curative treatment

BACKGROUND

The fucosylated fraction of alpha-fetoprotein (AFP-L3) has been used as a diagnostic marker for hepatocellular carcinoma (HCC). Recently, a highly sensitive immunoassay using an on-chip electrokinetic reaction and separation by affinity electrophoresis (micro-total analysis system; μTAS) has been developed.

AIM

The aim of this study was to investigate the relationship between changes in the serum AFP-L3 level measured by μTAS assay and recurrence of HCC after curative treatment.

METHODS

A total of 414 HCC patients who met the Milan criteria and underwent hepatectomy or radiofrequency ablation were investigated prospectively for the relationship between HCC recurrence and values of tumor markers.

RESULTS

There were significant differences in recurrence-free survival between groups with and without AFP-L3 elevation measured before and after treatment (p = 0.024 and p = 0.001 for before and after treatment, respectively). Multivariate analysis revealed that AFP-L3 status (p = 0.002) measured 1 month after treatment was a significant independent predictor of HCC recurrence after curative treatment.

CONCLUSIONS

Elevation of the serum AFP-L3 level before treatment is a predictor of HCC recurrence, and sustained elevation of the AFP-L3 level after treatment is an indicator of HCC recurrence. Repeated measurement of μTAS AFP-L3 should be performed for surveillance of HCC recurrence after curative treatment.

Novel Lens culinaris agglutinin-reactive fraction of α-fetoprotein: a biomarker of hepatocellular carcinoma recurrence in patients with low α-fetoprotein concentrations

BACKGROUND

Lens culinaris agglutinin-reactive fraction of α-fetoprotein (AFP-L3) is a specific marker used to detect hepatocellular carcinoma (HCC). However, its clinical utility is not sufficient in patients with low total AFP concentrations because of limitations in instrument sensitivity. Recent advances have led to the introduction of a highly sensitive AFP-L3% assay (sensitive AFP-L3%), provided by a novel on-chip, liquid-phase binding assay. This cross-sectional study was conducted to evaluate the clinical significance of the sensitive AFP-L3% in determining HCC recurrence in patients with low total AFP concentrations.

METHODS

A total of 370 consecutive patients with HCC were screened within 1-3 months of locoregional treatment, and 215 of the 370 patients showed serum AFP <20 ng/ml. Total AFP, sensitive AFP-L3%, and des-gamma-carboxy prothrombin (DCP) were measured in those 215 patients and HCC recurrence was evaluated by radiological findings. Optimal cutoff values of the markers for detecting HCC recurrence were obtained on the basis of receiver operating characteristic (ROC) curve.

RESULTS

The area under the ROC curve of the total AFP, sensitive AFP-L3%, and DCP in HCC patients with serum AFP <20 ng/ml were 0.638, 0.724, and 0.779, respectively. The diagnostic accuracies of the total AFP, sensitive AFP-L3%, and DCP were 60.9% (cutoff value 5 ng/ml), 67.7% (cutoff value 7%), and 64.6% (cutoff value 40 ng/ml), respectively.

CONCLUSIONS

The new sensitive AFP-L3% assay provides great utility in determining HCC recurrence in patients with low AFP concentrations. Further studies focusing on the combinatorial use of the markers (total AFP, sensitive AFP-L3%, and DCP) are required.

Clinical advantage of highly sensitive on-chip immunoassay for fucosylated fraction of alpha-fetoprotein in patients with hepatocellular carcinoma

BACKGROUND

Alpha-fetoprotein (AFP) has been widely used as a diagnostic master for hepatocellular carcinoma (HCC), and the fucosylated fraction of AFP (AFP-L3) has been reported to be a specific marker for HCC. However, AFP-L3 has not always been reliable in cases with low serum AFP concentrations. Recently, a novel automated immunoassay for AFP-L3, the micro-total analysis system (μ-TAS), has been developed.

AIM

The aim of this study is to evaluate the clinical usefulness of μ-TAS AFP-L3.

METHODS

Serum AFP-L3 was measured in 295 patients with HCC and in 350 with benign liver diseases. The diagnostic accuracy of μ-TAS AFP-L3 was compared with that of the conventional assay (liquid-phase binding assay; LiBASys). The relationship between μ-TAS AFP-L3 and clinical features was investigated.

RESULTS

When the cutoff value was set at 7%, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of μ-TAS AFP-L3 were 60.0%, 90.3%, 76.4%, 83.9%, and 72.8%, respectively. Its sensitivity was particularly good (41.1%) in HCC subgroups with lower AFP concentrations (<20 ng/ml). The positivity rates for μ-TAS AFP-L3 were higher at each tumor stage than those of LiBASys AFP-L3 (μ-TAS/LiBASys: stage I, 44.2%/16.3%; stage II, 52.9%/37.5%; stage III, 66.4%/44.5%; stage IV, 82.8%/65.5%).

CONCLUSIONS

μ-TAS AFP-L3 is more sensitive for discriminating HCC than the conventional LiBASys AFP-L3, particularly in subgroups with lower AFP concentrations and early-stage HCC.

Diagnostic value of lectin reactive alpha-fetoprotein for neoinfantile hepatic tumors and malignant germ cell tumors: preliminary study

BACKGROUND AND PURPOSE

The serum alpha-fetoprotein (AFP) level has been used as a tumor marker for hepatoblastoma, and malignant germ cell tumors in pediatric patients. The AFP has 3 isoforms (L1, L2, L3), and the usefulness of the L3 fraction as a diagnostic marker for the adult hepatocellular carcinoma is well known. However, there are few reports dealing with various pediatric malignant tumors. In the current study, we analyzed the diagnostic value of AFP fractions for pediatric diseases, in particular, those occurring in the neoinfantile period.

MATERIALS AND METHODS

From 2003 to 2006, two cases of hepatoblastoma, and 5 cases of germ cell tumor, all of which were neoinfantile, were treated in our department. In our analytical system (LiBASys), the level of the L3 fraction contains the majority of the L2 fraction. The total AFP (ng/mL) level and the L3 fraction (%) were measured to assess the usefulness of the L3 fraction as a diagnostic marker.

RESULTS

In all cases of hepatoblastoma and yolk sac tumor, both the total AFP and the L3 fraction were high, either before treatment or in the presence of malignant tumors. Most of the cases of neonatal immature teratoma showed a high total AFP level during the neoinfantile period, however, the L3 fraction was around 10%, and decreased after surgical treatment. Only 1 case of the immature teratoma demonstrated malignant transformation, when the patient was 8 months old. As the total AFP and the AFP-L3 fraction were proportionally elevated, the patient was treated with additional surgical resection and chemotherapy. In the case of neonatal mature teratoma, the L3 fraction was below 0.5%, even when the total AFP level was high.

DISCUSSION

Our results indicated that the level of the L3 fraction accurately confirmed the existence, or the malignant potential of hepatic tumor or germ cell tumor. The L3 fraction is useful as a tumor marker during the neoinfantile period.

Flow-injection chemiluminescent immunoassay for alpha-fetoprotein based on epoxysilane modified glass microbeads

A flow-injection chemiluminescent immunoassay system based on a novel transparent immunoaffinity reactor is proposed for the quantitation of alpha-fetoprotein. The reactor prepared with alpha-fetoprotein immobilized epoxysilane modified glass microbeads was used as an immunosensor for chemiluminescent detection. With a non-competitive immunoassay format, the proposed immunosensor system is a low cost, flexible and rapid assay for alpha-fetoprotein. After an off-line incubation of the analyte alpha-fetoprotein with horseradish peroxidase-labeled alpha-fetoprotein antibody as enzyme tracer, the mixture was injected into the reactor, which led to trapping of the free enzyme tracer by the reactor. The trapped enzyme tracer was detected by the p-iodophenol-luminol-H2O2 chemiluminescence system. Under optimal conditions, the decrease in chemiluminescence intensity was proportional to the alpha-fetoprotein concentration in the range of 5.0-100 ng/ml with a detection limit of 2.7 ng/ml at a signal/noise ratio of 3. The immunosensor system showed an acceptable reproducibility and stability. Clinical serum samples were assayed with this method and the results were in acceptable agreement with those obtained from immunoradiometric assay.

Simultaneous determination of percentage of Lens culinaris agglutinin-reactive alpha-fetoprotein and alpha-fetoprotein concentration using the LiBASys clinical auto-analyzer

BACKGROUND

Lens culinaris agglutinin (LCA)-reactive alpha-fetoprotein (AFP-L3) percentage of total AFP concentration [(AFP-L3/total AFP)x100] has been used as an effective marker for earlier diagnosis, for assessment of therapeutic effects and for predicting the prognosis of hepatocellular carcinoma (HCC).

METHODS

A new clinical automatic analyzer, the "LiBASys", and an assay kit for the simultaneous determination of AFP-L3 percentage and concentration of AFP in human serum were developed. LiBASys performed automatic re-measurement and also met stat samples. Both AFP-L3 percentage and AFP concentration were calculated simultaneously and printed out continuously every 3.4 min per test.

RESULTS

A linear dose-response relationship was observed up to 1000 ng/ml AFP concentration. The detection limit and functional sensitivity of LCA-nonreactive AFP (AFP-L1) and AFP-L3 concentrations were 0.4 and 0.8 ng/ml, and 0.4 and 1.0 ng/ml, respectively. Interassay CVs of AFP-L3 percentage and AFP concentration ranged from 2.8% to 13.4% and 2.6% to 4.6%, respectively. Assay results exhibited good correlations with those of commercially available lectin-affinity electrophoresis (r=0.984) for AFP-L3 percentage and with the RIA method (r=0.999) for AFP concentration.

CONCLUSIONS

This method simultaneously yields both qualitative and quantitative results for AFP-L3 percentage and AFP concentration.

AFP-L3: a new generation of tumor marker for hepatocellular carcinoma

BACKGROUND

Alpha-fetoprotein (AFP) from hepatocellular carcinoma (HCC) displays differential affinity to lectin Lens culinaris agglutinin (LCA) compared to that from chronic hepatitis/liver cirrhosis. According to their binding capability to LCA, total AFP can be separated into three different glycoforms, AFP-L1, AFP-L2, and AFP-L3. AFP-L1 is the non-LCA-bound fraction, which constitutes the major glycoform of AFP in serum of chronic hepatitis and liver cirrhosis. AFP-L3 is the LCA-bound fraction of AFP. It has been reported that malignant liver cells produce AFP-L3, even when HCC is at its early stages, and especially when the tumor mass is supplied by the hepatic artery. Clinical research has determined that AFP-L3 is a highly specific marker for HCC. The AFP-L3 can be detected in the serum of approximately 35% of the patients with small HCC (<2 cm). The AFP-L3-positive HCC has potential for rapid growth and early metastasis. Compared to imaging techniques, it has been shown to have 9-12 months of lead-time in early HCC recognition. Combined sensitivity of AFP-L3 for HCC is 56%, with a specificity of >95%.

METHODS

Automated assay for measuring AFP-L3 has been developed and introduced in clinical use. The new automated method for measurement of ALP-L3 is based on liquid phase binding of the AFP-L3 glycoform with LCA and two specific monoclonal antibodies labeled with peroxidase and polysulfated tyrosine peptide, respectively.

CONCLUSION

AFP-L3 is a new generation of tumor marker for HCC and yields useful information on HCC for clinical decision making.

Automatic and simultaneous analysis of Lens culinaris agglutinin-reactive alpha-fetoprotein ratio and total alpha-fetoprotein concentration

An automated analytical method for analyzing alpha-fetoprotein (AFP) carbohydrate chain microheterogeneity based on competitive reaction between lectin and anti-AFP monoclonal antibody in liquid phase is described. The antibody used binds to all species of AFP molecule without Lens culinaris agglutinin (LCA); however, its binding reaction to LCA-reactive AFP was inhibited by LCA. Sulfated tyrosine octamer was conjugated to the antibody, and sulfated tyrosine pentamer and peroxidase were conjugated to other monoclonal antibodies, respectively. Serum reacted with three anti-AFP monoclonal antibodies and LCA in liquid phases, and two types of immune complex were observed. The two types were separated directly by the liquid-phase binding assay system equipped with an anion-exchange column. Peroxidase activity of immune complex was determined fluorophotometrically. Total AFP concentration and the ratio of LCA-reactive AFP in samples were calculated simultaneously, using the sum of the two peaks and the ratio of peaks obtained by LCA inhibition to sum of two peaks. The results correlated well with conventional methods. The method is simple and convenient for routine clinical assays.

Determination of alpha-fetoprotein concentration based on liquid-phase binding assay using anion exchange chromatography and sulfated peptide introduced antibody

A new immunoassay for alpha-fetoprotein based upon liquid-phase binding reactions is described. In this procedure, a sample that contains alpha-fetoprotein is mixed with a solution of two anti-alpha-fetoprotein monoclonal antibodies complexed with peroxidase and sulfated peptide, respectively. After incubation, immune complex is separated from other components by anion exchange column chromatography. Immune complex is quantified using fluorometric detection by peroxidase enzymatic activity. Peroxidase activity correlated with a alpha-fetoprotein with a 1:1 relationship. The stoichiometric immunoreaction allowed a large analytical range (0.4-7500 ng/ml) with a linear dose-response relationship, high sensitivity and good precision. Endogenous substances did not interfere with assay performance. Assay results showed good correlation with other established methods. These results indicate that the method is useful for clinical alpha-fetoprotein determinations.