Assessment of KL-6 as a tumor marker in patients with hepatocellular carcinoma

A case of pleural mesothelioma with immunohistochemical staining positive for Krebs von den Lungen-6

A 71-year-old male visited a hospital with a chief complaint of exertional dyspnea. A chest CT revealed multiple nodular lesions on the parietal pleura. Thoracoscopic pleural biopsy was performed resulting in a diagnosis of pleural mesothelioma with epithelioid type. When chemotherapy was initially initiated, his serum level of Krebs von den Lungen-6 (KL-6) was high. However, once chemotherapy was started, the serum KL-6 level gradually decreased with tumor shrinkage. Immunohistochemical staining revealed the expression of KL-6 from the tumor cells. This is the first report of KL-6 production directly from tumor cells in epithelial-type pleural mesothelioma.

Safety and effectiveness of certolizumab pegol in Japanese patients with rheumatoid arthritis: Up to 3-year results from a postmarketing surveillance study

OBJECTIVES

To report up to 3-year safety and effectiveness of certolizumab pegol (CZP) in Japanese patients with rheumatoid arthritis from a postmarketing surveillance study.

METHODS

Patients enrolled previously completed 24 weeks of CZP in the 24-week postmarketing surveillance study. Adverse drug reactions (ADRs) were recorded for patients who received ≥1 CZP dose. Effectiveness outcomes were 28-joint Disease Activity Score with erythrocyte sedimentation rate and European Alliance of Associations for Rheumatology response. Week 24-156 safety and Week 0-52 effectiveness data are reported here.

RESULTS

A total of 781 patients were enrolled, with 735 and 376 patients evaluated for safety and effectiveness, respectively. Within the safety set, 17.8% (131/735) of patients reported ADRs; 9.4% (69/735) reported serious ADRs. Among patients with history of respiratory, thoracic, and mediastinal disorders, 38.4% (28/73) reported ADRs. The most frequent ADRs were infections and infestations (11.8%; 87/735); skin and subcutaneous tissue disorders (1.9%; 14/735); respiratory, thoracic, and mediastinal disorders (1.6%; 12/735). Mean 28-joint Disease Activity Score with erythrocyte sedimentation rate reduced from 4.6 (Week 0) to 2.8 (Week 52). At Week 52, 51.8% (161/311) of patients achieved European Alliance of Associations for Rheumatology Good response.

CONCLUSIONS

The long-term safety and effectiveness of CZP in the real-world setting in Japan were consistent with previously reported data; no new safety signals were identified.

Clinical significance of KL-6 in immune-checkpoint inhibitor treatment for non-small cell lung cancer

PURPOSE

Krebs von den Lungen-6 (KL-6) functions as a tumor marker, as well as a diagnostic tool for interstitial pneumonia (IP). However, the significance of KL-6 in the immune-checkpoint inhibitor (ICI) treatment of non-small cell lung cancer (NSCLC), especially in patients without IP, is unknown.

METHODS

This multicenter, retrospective study, which included patients with advanced NSCLC who received ICI therapy, analyzed the association between serum KL-6 values and ICI efficacy and the association between serum KL-6 values and ICI-induced interstitial lung disease (ILD) occurrence, focusing primarily on patients without IP.

RESULTS

In total, 322 patients had available KL-6 values before ICI therapy. Among 202 patients without IP who received ICI monotherapy, the high-KL-6 group (≥ 500 U/mL) showed significantly shorter progression-free survival (PFS) and overall survival (OS) than the low-KL-6 group (< 500 U/mL) (median: 2.1 vs. 3.6 months, p = 0.048; median: 9.2 vs. 14.5 months, p = 0.035). There was no significant difference in response rate between the KL-6 high and low groups (19% vs. 29%, p = 0.14). In the multivariate analysis, high KL-6 was a significant predictor of poor PFS (hazard ratio [HR], 1.52; 95% confidence interval [CI] 1.10-2.11, p = 0.012) and OS (HR, 1.51; 95% CI 1.07 - 2.13, p = 0.019) for patients treated with ICI monotherapy. There was no significant difference in the occurrence rate of ILD between the high KL-6 and low KL-6 groups in patients with (20% vs. 15%, p = 1.00) or without IP (12% vs. 12%, p = 1.00).

CONCLUSION

In ICI monotherapy for NSCLC without IP, elevated serum KL-6 levels were associated with poorer outcomes.

Multidisciplinary clinical guidance on trastuzumab deruxtecan (T-DXd)-related interstitial lung disease/pneumonitis-Focus on proactive monitoring, diagnosis, and management

Trastuzumab deruxtecan (T-DXd; DS-8201) is an antibody-drug conjugate targeting human epidermal growth factor receptor 2. Interstitial lung disease (ILD)/pneumonitis is an adverse event associated with T-DXd; in most cases, it is low grade (grade ≤ 2) and can be treated effectively but may develop to be fatal in some instances. It is important to increase patient and provider understanding of T-DXd-related ILD/pneumonitis to improve patient outcomes. Drug-related ILD/pneumonitis is a diagnosis of exclusion; other possible causes of lung injury/imaging findings must be ruled out for an accurate diagnosis. Symptoms can be nonspecific, and identifying early symptoms is challenging; therefore, diagnosis is often delayed. We reviewed characteristics of patients who developed T-DXd-related ILD/pneumonitis and its patterns, produced multidisciplinary guidelines on diagnosis and management, and described areas for future investigation. Ongoing studies are collecting data on T-DXd-related ILD/pneumonitis to further our understanding of its clinical patterns and mechanisms. SEARCH STRATEGY AND SELECTION CRITERIA: References were identified based on the guidelines used by the authors in treating interstitial lung disease and pneumonitis. Searches of the authors' own files were also completed. A search of PubMed with the search terms (trastuzumab deruxtecan) AND (interstitial lung disease) AND (guidelines) was conducted on November 1, 2021, with no restrictions based on publication date, and the two articles yielded by the search were included.

Abdominal ultrasound and alpha-foetoprotein for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma (HCC) occurs mostly in people with chronic liver disease and ranks sixth in terms of global instances of cancer, and fourth in terms of cancer deaths for men. Despite that abdominal ultrasound (US) is used as an initial test to exclude the presence of focal liver lesions and serum alpha-foetoprotein (AFP) measurement may raise suspicion of HCC occurrence, further testing to confirm diagnosis as well as staging of HCC is required. Current guidelines recommend surveillance programme using US, with or without AFP, to detect HCC in high-risk populations despite the lack of clear benefits on overall survival. Assessing the diagnostic accuracy of US and AFP may clarify whether the absence of benefit in surveillance programmes could be related to under-diagnosis. Therefore, assessment of the accuracy of these two tests for diagnosing HCC in people with chronic liver disease, not included in surveillance programmes, is needed.

OBJECTIVES

Primary: the diagnostic accuracy of US and AFP, alone or in combination, for the diagnosis of HCC of any size and at any stage in adults with chronic liver disease, either in a surveillance programme or in a clinical setting. Secondary: to assess the diagnostic accuracy of abdominal US and AFP, alone or in combination, for the diagnosis of resectable HCC; to compare the diagnostic accuracy of the individual tests versus the combination of both tests; to investigate sources of heterogeneity in the results.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic-Test-Accuracy Studies Register, Cochrane Library, MEDLINE, Embase, LILACS, Science Citation Index Expanded, until 5 June 2020. We applied no language or document-type restrictions.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of US and AFP, independently or in combination, for the diagnosis of HCC in adults with chronic liver disease, with cross-sectional and case-control designs, using one of the acceptable reference standards, such as pathology of the explanted liver, histology of resected or biopsied focal liver lesion, or typical characteristics on computed tomography, or magnetic resonance imaging, all with a six-months follow-up.

DATA COLLECTION AND ANALYSIS

We independently screened studies, extracted data, and assessed the risk of bias and applicability concerns, using the QUADAS-2 checklist. We presented the results of sensitivity and specificity, using paired forest-plots, and tabulated the results. We used a hierarchical meta-analysis model where appropriate. We presented uncertainty of the accuracy estimates using 95% confidence intervals (CIs). We double-checked all data extractions and analyses.

MAIN RESULTS

We included 373 studies. The index-test was AFP (326 studies, 144,570 participants); US (39 studies, 18,792 participants); and a combination of AFP and US (eight studies, 5454 participants). We judged at high-risk of bias all but one study. Most studies used different reference standards, often inappropriate to exclude the presence of the target condition, and the time-interval between the index test and the reference standard was rarely defined. Most studies with AFP had a case-control design. We also had major concerns for the applicability due to the characteristics of the participants. As the primary studies with AFP used different cut-offs, we performed a meta-analysis using the hierarchical-summary-receiver-operating-characteristic model, then we carried out two meta-analyses including only studies reporting the most used cut-offs: around 20 ng/mL or 200 ng/mL. AFP cut-off 20 ng/mL: for HCC (147 studies) sensitivity 60% (95% CI 58% to 62%), specificity 84% (95% CI 82% to 86%); for resectable HCC (six studies) sensitivity 65% (95% CI 62% to 68%), specificity 80% (95% CI 59% to 91%). AFP cut-off 200 ng/mL: for HCC (56 studies) sensitivity 36% (95% CI 31% to 41%), specificity 99% (95% CI 98% to 99%); for resectable HCC (two studies) one with sensitivity 4% (95% CI 0% to 19%), specificity 100% (95% CI 96% to 100%), and one with sensitivity 8% (95% CI 3% to 18%), specificity 100% (95% CI 97% to 100%). US: for HCC (39 studies) sensitivity 72% (95% CI 63% to 79%), specificity 94% (95% CI 91% to 96%); for resectable HCC (seven studies) sensitivity 53% (95% CI 38% to 67%), specificity 96% (95% CI 94% to 97%). Combination of AFP (cut-off of 20 ng/mL) and US: for HCC (six studies) sensitivity 96% (95% CI 88% to 98%), specificity 85% (95% CI 73% to 93%); for resectable HCC (two studies) one with sensitivity 89% (95% CI 73% to 97%), specificity of 83% (95% CI 76% to 88%), and one with sensitivity 79% (95% CI 54% to 94%), specificity 87% (95% CI 79% to 94%). The observed heterogeneity in the results remains mostly unexplained, and only in part referable to different cut-offs or settings (surveillance programme compared to clinical series). The sensitivity analyses, excluding studies published as abstracts, or with case-control design, showed no variation in the results. We compared the accuracy obtained from studies with AFP (cut-off around 20 ng/mL) and US: a direct comparison in 11 studies (6674 participants) showed a higher sensitivity of US (81%, 95% CI 66% to 90%) versus AFP (64%, 95% CI 56% to 71%) with similar specificity: US 92% (95% CI 83% to 97%) versus AFP 89% (95% CI 79% to 94%). A direct comparison of six studies (5044 participants) showed a higher sensitivity (96%, 95% CI 88% to 98%) of the combination of AFP and US versus US (76%, 95% CI 56% to 89%) with similar specificity: AFP and US 85% (95% CI 73% to 92%) versus US 93% (95% CI 80% to 98%).

AUTHORS' CONCLUSIONS

In the clinical pathway for the diagnosis of HCC in adults, AFP and US, singularly or in combination, have the role of triage-tests. We found that using AFP, with 20 ng/mL as a cut-off, about 40% of HCC occurrences would be missed, and with US alone, more than a quarter. The combination of the two tests showed the highest sensitivity and less than 5% of HCC occurrences would be missed with about 15% of false-positive results. The uncertainty resulting from the poor study quality and the heterogeneity of included studies limit our ability to confidently draw conclusions based on our results.

Microfluidic chip electrophoresis for simultaneous fluorometric aptasensing of alpha-fetoprotein, carbohydrate antigen 125 and carcinoembryonic antigen by applying a catalytic hairpin assembly

An aptamer based assay is presented that is making use of a catalytic hybrid assembly and a microfluidic chip electrophoresis format. It enables simultaneous determination of the biomarkers (BMs) α-fetoprotein (AFP), carbohydrate antigen 125 (CA125), and carcinoembryonic antigen (CEA). The respective aptamers were covalently bound to Fe₃O₄@AuNPs (AuMPs) magnetic beads and then used to capture the biomarkers on their surface. Different single-stranded DNA primers were then labeled with various antibodies as encoding and signaling tags. The signal tags reacted with AuMPs-BMs to form different antibody-BM-aptamer complexes. After magnetic separation, three pairs of hairpins as substrates were introduced to trigger catalytic hybrid assembly by the primers in the complex. This will form many duplex DNA products of different length in the supernatant. The products can be magnetically separated by microfluidic chip electrophoresis and determined by fluorometry at excitation/emission wavelengths of 495/525 nm. Several experimental conditions including the hairpin concentration, reaction time and temperature were systemically optimized. The method can simultaneously quantify AFP, CEA and CA125, respectively, with detection limits of 0.1, 0.2, 0.15 pg mL^-1 (at S/N = 3). The aptamer functionalized magnetic beads can be reused for at least 20 times with a recovery of up to 80% after heat treatment. The method was employed to simultaneously detect the three BMs in serum samples. Graphical abstract Schematic presentation of the microfluidic chip electrophoresis and antibody-aptamer based multianalysis method for simultaneous detection of alpha-fetoprotein (AFP), carbohydrate antigen 125 (CA125) and carcinoembryonic antigen (CEA).

Mucins: the Old, the New and the Promising Factors in Hepatobiliary Carcinogenesis

Mucins are large O-glycoproteins with high carbohydrate content and marked diversity in both the apoprotein and the oligosaccharide moieties. All three mucin types, trans-membrane (e.g., MUC1, MUC4, MUC16), secreted (gel-forming) (e.g., MUC2, MUC5AC, MUC6) and soluble (non-gel-forming) (e.g., MUC7, MUC8, MUC9, MUC20), are critical in maintaining cellular functions, particularly those of epithelial surfaces. Their aberrant expression and/or altered subcellular localization is a factor of tumour growth and apoptosis induced by oxidative stress and several anti-cancer agents. Abnormal expression of mucins was observed in human carcinomas that arise in various gastrointestinal organs. It was widely believed that hepatocellular carcinoma (HCC) does not produce mucins, whereas cholangiocarcinoma (CC) or combined HCC-CC may produce these glycoproteins. However, a growing number of reports shows that mucins can be produced by HCC cells that do not exhibit or are yet to undergo, morphological differentiation to biliary phenotypes. Evaluation of mucin expression levels in precursors and early lesions of CC, as well as other types of primary liver cancer (PLC), conducted in in vitro and in vivo models, allowed to discover the mechanisms of their action, as well as their participation in the most important signalling pathways of liver cystogenesis and carcinogenesis. Analysis of mucin expression in PLC has both basic research and clinical value. Mucins may act as oncogenes and tumour-promoting (e.g., MUC1, MUC13), and/or tumour-suppressing factors (e.g., MUC15). Given their role in promoting PLC progression, both classic (MUC1, MUC2, MUC4, MUC5AC, MUC6) and currently tested mucins (e.g., MUC13, MUC15, MUC16) have been proposed to be important diagnostic and prognostic markers. The purpose of this review was to summarize and update the role of classic and currently tested mucins in pathogenesis of PLC, with explaining the mechanisms of their action in HCC carcinogenesis. It also focuses on determination of the diagnostic and prognostic role of these glycoproteins in PLC, especially focusing on HCC, CC and other hepatic tumours with- and without biliary differentiation.

Pre-operative evaluation of circulating KL-6 levels as a biomarker for epithelial ovarian carcinoma and its correlation with tumor MUC1 expression

Krebs von den Lungen-6 (KL-6), a mucinous sialylated sugar chain on human mucin-1 glycoprotein (MUC1), is a diagnostic marker for interstitial lung diseases. Furthermore, elevated serum KL-6 levels have been observed in certain malignant tumor types of epithelial origin. The expression of MUC1 has been observed in patients with epithelial ovarian cancer (EOC) and is considered a potential therapeutic target. In the present study, KL-6 serum levels were investigated in patients clinically suspected of having malignant ovarian tumors. A total of 219 patients were enrolled in the study, which analyzed their serum KL-6 levels in addition to tumor expression of MUC1 using immunohistochemistry. High serum KL-6 levels were predominantly observed in patients with EOC, and did not occur in patients with benign or borderline tumors. The level of serum KL-6 was highly correlated with tumor stage, grade and histological type, and demonstrated superior sensitivity for the detection of ovarian cancer compared with that of serum cancer antigen 125. High serum KL-6 was significantly associated with shorter progression-free survival. In addition, tumor MUC1 expression status was significantly correlated with serum KL-6 levels. These data suggest that serum KL-6 may be a useful, non-invasive biomarker surrogate for tumor MUC1 expression in future clinical trials of MUC1-targeted therapy.

Effects of the multiple O-glycosylation states on antibody recognition of the immunodominant motif in MUC1 extracellular tandem repeats

The conformational impact of the clusteredO-glycans strongly influences recognition by antibodies of the cancer-relevant epitope in the MUC1 extracellular tandem repeat domain.

Mucin 1 gene silencing inhibits the growth of SMMC-7721 human hepatoma cells through Bax-mediated mitochondrial and caspase-8-mediated death receptor apoptotic pathways

Mucin 1 (MUC1) is an oncogene that has a crucial role in the pathogenesis and progression of the majority of epithelial malignant tumors. Our previous study demonstrated that MUC1 gene silencing inhibited the growth of SMMC-7721 cells in vitro and in vivo, however, whether this growth inhibition is associated with apoptotic cell death remains to be elucidated. In the present study, it was found that MUC1 gene silencing not only resulted in the inhibition of SMMC-7721 cell growth, determined using a clone formation assay in vitro and a tumor xenograft mouse model with an in vivo imaging system, but also induced apoptotic alterations in SMMC-7721 cells, determined using Hoechst 33342 staining, flow cytometry with an Annexin V-PE staining and a DNA ladder assay. Further investigation using western blotting revealed that cytochrome c was released from the mitochondria into the cytoplasm, and caspase-8 and caspase-9 were activated in MUC1 gene-silenced SMMC-7721 cells. The pro-apoptotic protein Bcl-2-associated X protein (Bax) and the tumor suppressor p53 were increased, while the anti-apoptotic protein B-cell lymphoma 2 was decreased in MUC1 gene-silenced cells. In addition, results from the co-immunoprecipitation experiments demonstrated that the MUC1 cytoplasmic tail can bind directly to Bax or caspase-8 and these interactions were reduced upon MUC1 gene silencing in SMMC-7721 cells. The above results indicate that MUC1 gene silencing induces growth inhibition in SMMC-7721 cells through Bax-mediated mitochondrial and caspase-8-mediated death receptor apoptotic pathways.

Serological tumor markers of hepatocellular carcinoma: a meta-analysis

BACKGROUND

The clinical value of serum α-fetoprotein (AFP) to detect hepatocellular carcinoma (HCC) has been questioned due to its low sensitivity and specificity. Other than AFP, several new serum biomarkers including glypican-3 (GPC3), des-γ-carboxy prothrombin (DCP), α-L-fucosidase enzyme (AFU) and vascular endothelial growth factor (VEGF) have been identified as useful HCC markers.

MATERIAL AND METHODS

A systematic search on PubMed, Web of Science and others was performed. Twenty-six case-control studies on HCC-related biomarkers published from 2000 to 2014 were included in this analysis. Data on sensitivity and specificity of tests were extracted and analyzed using the Meta-DiSc 1.4 statistical program. Fixed or random-effects models were used depending on the absence or presence of significant heterogeneity. Summary receiver operating characteristic (sROC) curves were obtained to evaluate the accuracy of the studied markers.

RESULTS

The areas under the sROC curve of AFP, GPC3, DCP, AFU, VEGF and the combination of each of the last 4 markers with AFP were 0.869, 0.928, 0.832, 0.851, 0.834, 0.964, 0.972, 0.873 and 0.948, respectively. A combination of AFP+GPC3, AFP+DCP or AFP+VEGF was superior to AFP alone in detecting HCC. The area under the sROC curve of GPC3 alone was significantly higher than that of AFP, whereas the areas of DCP, AFU and VEGF were comparable to that of AFP.

CONCLUSIONS

GPC3, DCP, AFU and VEGF are suitable markers for HCC, and their determination with AFP may prove to be useful in the diagnosis and screening of HCC.

Site-specific conformational alteration induced by sialylation of MUC1 tandem repeating glycopeptides at an epitope region for the anti-KL-6 monoclonal antibody

Protein O-glycosylation is an essential step for controlling structure and biological functions of glycoproteins involving differentiation, cell adhesion, immune response, inflammation, and tumorigenesis and metastasis. This study provides evidence of site-specific structural alteration induced during multiple sialylation at Ser/Thr residues of the tandem repeats in human MUC1 glycoprotein. Systematic nuclear magnetic resonance (NMR) study revealed that sialylation of the MUC1 tandem repeating glycopeptide, Pro-Pro-Ala-His-Gly-Val-Thr-Ser-Ala-Pro-Asp-Thr-Arg-Pro-Ala-Pro-Gly-Ser-Thr-Ala with core 2-type O-glycans at five potential glycosylation sites, afforded a specific conformational change at one of the most important cancer-relevant epitopes (Pro-Asp-Thr-Arg). This result indicates that disease-relevant epitope structures of human epithelial cell surface mucins can be altered both by the introduction of an inner GalNAc residue and by the distal sialylation in a peptide sequence-dependent manner. These data demonstrate the feasibility of NMR-based structural characterization of glycopeptides synthesized in a chemical and enzymatic manner in examining the conformational impact of the distal glycosylation at multiple O-glycosylation sites of mucin-like domains.

Distinct Cytoplasmic Expression of KL-6 Mucin in Chromophobe Renal Cell Carcinoma: A Comparative Immunohistochemical Study with Other Renal Epithelial Cell Tumors

The presence of cytoplasmic sialyl glycoproteins is a conspicuous feature in chromophobe renal cell carcinoma (RCC). We compared the immunohistochemical expression of sialyl glycoproteins in chromophobe RCC with that in other types of renal tumors. Formalin-fixed, paraffin-embedded tissues of surgically resected renal tumors (chromophobe RCC, 14 cases [10 cases of classic type and 4 cases of eosinophilic variant]; oncocytoma, 7 cases; and clear cell RCC, 9 cases) and kidneys from immature infants (4 cases) were immunostained with antibodies against sialyl glycoproteins (anti-KL-6 and anti-sialyl MUC1 antibodies). Cytoplasmic expression of KL-6 and sialyl MUC1 was distinctive in the chromophobe RCC and renal oncocytoma cells, and in the intercalated cells in collecting duct epithelia. Apical-surface staining of these sialyl glycoproteins was predominantly observed in clear RCC, in the epithelia of the distal tubule and collecting duct, and in the neonatal renal proximal tubule, but not in those of the adult renal proximal tubule. The above-mentioned observations provide additional evidence for similar phenotypic profiles of chromophobe RCC and renal oncocytoma, and the intercalated cells in collecting ducts and the oncofetal expression of sialyl glycoproteins in clear cell RCC. KL-6 is a potential tumor marker for renal tumors.

An overview of biomarkers for the diagnosis of hepatocellular carcinoma

CONTEXT

Primary liver cancer is one of the most common and deadly malignant neoplasms worldwide. The incidence and mortality rates for hepatocellular carcinoma (HCC) are virtually identical, reflecting the poor overall survival of patients with this kind of tumor. Effective therapies mostly achieved if the HCC diagnosis is made at early stages of the tumor. Surveillance tests include serologic and radiologic examinations.

EVIDENCE ACQUISITION

In this review, an overview of biomarkers for the diagnosis of HCC and future challenges in this popular field has been presented.

RESULTS

Serum tumor markers, such as alpha-fetoprotein (AFP) and des-gammacarboxy prothrombin (DCP) are commonly used for the surveillance, but their roles have been intensely debated despite the existence of sensitive radiologic tests. Most HCC-related cancer biomarkers are involved in chronic inflammation and cancer. These biomarkers, according to their biologic characteristics are primarily divided into three groups including onco-foetal protein, stress protein, and post-translational modification.

CONCLUSIONS

Because of the limitations of traditional HCC biomarkers, exploration for novel biomarkers for the diagnosis of HCC is an evolving process.

Novel O-linked glycans containing 6'-sulfo-Gal/GalNAc of MUC1 secreted from human breast cancer YMB-S cells: possible carbohydrate epitopes of KL-6(MUC1) monoclonal antibody

Human serum Krebs von den Lugen-6 (KL-6) antigen is a MUC1 glycoprotein (KL-6/MUC1) recognized by anti-KL-6 monoclonal antibody (KL-6/mAb) and has been utilized as a diagnostic marker for interstitial pneumonia. KL-6/mAb is thought to recognize the specific glycopeptides sequence of MUC1, but the precise glycan structure of the epitope is unclear. In this study, we determined the carbohydrate structures of KL-6/MUC1 to search the carbohydrate epitopes for KL-6/mAb. KL-6/MUC1 was purified from the culture medium of human breast cancer YMB-S cells by KL-6/mAb-affinity chromatography; the O-linked glycan structures were determined in combination with paper electrophoresis, several lectin column chromatographies, sialidase digestion and methanolysis. KL-6/MUC1 contained core 1 and extended core 1 glycans modified with one or two sialic acid/sulfate residues. Based on these structures, several synthetic glycans binding to anti-KL-6/mAb were compared with one another by surface plasmon resonance. Sequentially, related radiolabeled oligosaccharides were enzymatically synthesized and analyzed for binding to a KL-6/mAb-conjugated affinity column. 3'-sialylated, 6'-sulfated LNnT [Neu5Acα2-3(SO(3)(-)-6)Galβ1-4GlcNAcβ1-3Galβ1-4Glc], 3'-sialylated, 6-sulfated core 1 [Neu5Acα2-3Galβ1-3(SO(3)(-)-6)GalNAc] and disulfated core 1 SO(3)(-)-3Galβ1-3(SO(3)(-)-6)GalNAc exhibited substantial affinity for KL-6/mAb, and 3'-sulfated core 1 derivatives [SO(3)(-)-3Galβ1-3(±Neu5Acα2-6)GalNAc] and 3'-sialylated core 1 weakly interacted with KL-6/mAb. These results indicated that the possible carbohydrate epitopes of KL-6/mAb involve not only 3'-sialylated core 1 but also novel core 1 and extended core 1 with sulfate and sialic acid residues. Epitope expressing changes with suppression or over-expression of the Gal6ST (Gal 6-O-sulfotransferase) gene, suggesting that Gal6ST is involved in the biosynthesis of the unique epitopes of KL-6/mAb.

Elevation of serum KL-6 levels in 3 patients with rheumatoid arthritis treated with adalimumab

We describe 3 cases of rheumatoid arthritis presenting with elevated serum KL-6 levels during treatment with adalimumab, which was discontinued because of suspected onset of complications. However, no complications were observed following discontinuation despite comprehensive assessments, and KL-6 levels subsequently returned to baseline levels. In our institutes, 3 out of 29 cases treated with adalimumab showed elevated KL-6 levels. The baseline levels were 445, 347, and 547 U/ml, while the peak levels were 1010, 546, and 2007 U/ml, respectively. The elevated KL-6 levels seem to have been innocuous; nevertheless, further careful observation is deemed necessary.

Present and future possibilities for early diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents the fifth most common cancer in the world, and the third most frequent oncological cause of death. The incidence of HCC is on the increase. HCC typically develops in patients with chronic liver diseases, and cirrhosis, usually with viral etiology, is the strongest predisposing factor. Nowadays HCC diagnosis is a multistage process including clinical, laboratory, imaging and pathological examinations. The prognosis of HCC is mostly poor, because of detection at an advanced, non-resectable stage. Potentially curative treatment (surgery) is limited and really possible only for cases with small HCC malignancies. For this reason, more effective surveillance strategies should be used to screen for early occurrence of HCC targeted to the population at risk. So far, the generally accepted serological marker is α-fetoprotein (AFP). Its diagnostic accuracy is unsatisfactory and questionable because of low sensitivity, therefore there is a strong demand by clinicians for new HCC-specific biomarkers. In this review, we will focus on other biomarkers that seem to improve HCC diagnosis, such as AFP-L3, des-γ-carboxyprothrombin, α-l-fucosidase, γ-glutamyl transferase, glypican-3, squamous cell carcinoma antigen, a new generation of immunoglobulin M-immunocomplexes, and very promising gene-expression profiling.

An essential epitope of anti-MUC1 monoclonal antibody KL-6 revealed by focused glycopeptide library

Human serum Krebs von den Lungen-6 (KL-6) antigen, a high-molecular-weight glycoprotein classified as a polymorphic epithelial mucin (MUC1), is a biomarker of diseases such as interstitial pneumonia, lung adenocarcinoma, breast cancer, colorectal adenocarcinoma, and hepatocellular carcinoma. Anti-KL-6 monoclonal antibody (anti-KL-6 MAb) is therefore a potential diagnostic and therapeutic reagent. Although glycosylation at Thr/Ser residues of the tandem-repeating MUC1 peptides appears to determine the disease-associated antigenic structures of KL-6, an essential epitope structure recognized by anti-KL-6 MAb remains unclear. In the present study, a novel compound library of synthetic MUC1 glycopeptides allowed the first rapid and precise evaluation of the specific epitope structure of anti-KL-6 MAb by combined use of a tailored glycopeptides library and common ELISA protocol. We demonstrated that the minimal antigenic structure, an essential epitope, recognized by anti-KL-6 MAb is a heptapeptide sequence Pro-Asp-Thr-Arg-Pro-Ala-Pro (PDTRPAP), in which the Thr residue is modified by Neu5Ac alpha2,3Gal beta1,3GalNAc alpha (2,3-sialyl T antigen, core 1-type O-glycan). Anti-KL-6 MAb did not bind with other tumor-relevant antigens, such as GalNAc alpha (Tn), Neu5Ac alpha2,6GalNAc alpha (STn), and Gal beta1,3GalNAc alpha (T), except for Neu5Ac alpha2,3Gal beta1,3(Neu5Ac alpha2,6)GalNAc alpha (2,3/2,6-disialyl T). However, anti-KL-6 MAb could not differentiate the above minimal antigenic glycopeptide from some core 2-based glycopeptides involving this crucial epitope structure and showed a similar binding affinity toward these compounds, indicating that branching at the O-6 position of GalNAc residue does not influence the interaction of anti-KL-6 MAb with some MUC1 glycoproteins involving an essential epitope. Actually, anti-KL-6 MAb reacts with 2,3/2,6-disialyl T having a 2,3-sialyl T component. This is why anti-KL-6 MAb often reacts with various kinds of tumor-derived MUC1 glycoproteins as well as a clinically important MUC1 glycoprotein biomarker of interstitial pneumonia, namely KL-6, originally discovered as a circulating pulmonary adenocarcinoma-associated antigen. In other words, combined use of anti-KL-6 MAb and some probes that can differentiate the sugars substituted at the O-6 position of the GalNAc residue in MUC1 glycopeptides including the PDTRPAP sequence might be a promising diagnostic protocol for individual disease-specific biomarkers. It was also revealed that glycosylation at neighboring Thr/Ser residues outside the immunodominant PDTRPAP motif strongly influences the interaction between anti-KL-6 MAb and MUC1 glycopeptides involving the identified epitope. Our novel strategy will greatly facilitate the processes for the identification of the tumor-specific and strong epitopes of various known anti-MUC1 MAbs and allow for their practical application in the generation of improved antibody immunotherapeutics, diagnostics, and MUC1-based cancer vaccines.

An overview of hepatocellular carcinoma study by omics-based methods

Hepatocellular carcinoma (HCC) is one of the most deadly malignancies worldwide. Scientists have been studying the molecular mechanism of HCC for years, but the understanding of it remains incomplete and scattered across the literature at different molecular levels. Chromosomal aberrations, epigenetic abnormality and changes of gene expression have been reported in HCC. High-throughput omics technologies have been widely applied, aiming at the discovery of candidate biomarkers for cancer staging, prediction of recurrence and prognosis, and treatment selection. Large amounts of data on genetic and epigenetic abnormalities, gene expression profiles, microRNA expression profiles and proteomics have been accumulating, and bioinformatics is playing a more and more important role. In this paper, we review the current omics-based studies on HCC at the levels of genomics, transcriptomics and proteomics. Integrating observations from multiple aspects is an essential step toward the systematic understanding of the disease.

A concise review of serum markers for hepatocellular cancer

BACKGROUND

The rising incidence of hepatocellular cancer in the US and worldwide has sparked a renewed interest in HCC serum markers. HCC typically develops in patients with chronic liver disease and cirrhosis. It is in these target populations that serum markers are most urgently needed. Unfortunately, the currently available markers lack sensitivity and specificity. A number of novel candidate markers have recently been introduced.

METHODS

We performed a review of the literature (2001-2006) of traditional and novel serum markers for hepatocellular cancer.

RESULTS

Several promising new HCC markers have been identified over the past 5 years. They include single proteins, complex proteomics features, and tumor-specific autoantibodies. The excitement about the new markers is tempered by the realization that none of them have yet met the most stringent criteria defined by the Early Detection Research Network (EDRN).

CONCLUSION

A new generation of HCC serum markers awaits validation in properly controlled clinical studies.