Difference in tissue expression of tumour markers CA 19-9 and CA 50 in hepatocellular carcinoma and cholangiocarcinoma.

The expression of tumour markers CA 19-9 and CA 50, defined by the monoclonal antibodies 1116 NS 19-9 (19-9 antibody) and C 50, was studied by the immunoperoxidase technique in formalin-fixed, paraffin-embedded tissue sections from 11 hepatocellular carcinomas and 10 cholangiocarcinomas of the liver, and from specimens of normal liver and liver cirrhosis. The 19-9 and C 50 antibodies react with sialosylfucosyllactotetraose, corresponding to sialylated blood group antigen Lewis, and the C 50 antibody also with another sugar moiety, sialosyllactotetraose. Neither marker was cancer specific. The CA 19-9 and CA 50 antigens are normal constituents of bile ducts. Nine out of 10 cholangiocarcinomas stained for CA 50, and eight out of 10 for CA 19-9. There was no apparent difference between the staining pattern of CA 19-9 and CA 50. Hepatocellular carcinomas were consistently negative for both markers. Thus, hepatocellular carcinomas and cholangiocarcinomas showed a clear difference in the reactivity for tumour marker antigens CA 19-9 and CA 50. This difference might be of clinical importance in the differential diagnosis between hepatocellular carcinoma and cholangiocarcinoma.     

Tissue expression of the tumor marker CA 50 in benign and malignant pancreatic lesions. A comparison with CA 19-9

The expression of the tumor marker antigen CA 50, defined by the monoclonal antibody (MAb) C 50, was studied by the immunoperoxidase technique in formalin-fixed, paraffin-embedded tissue sections from normal pancreata, from pancreata with pancreatitis and from benign and malignant pancreatic neoplasms. The results were compared with those obtained with Mab 1116 NS 19-9. The C 50 antibody reacts, like the 1116 NS 19-9 antibody, with sialosylfucosyllactotetraose (corresponding to sialylated blood group antigen Lewisa), but also with another sugar moiety, sialosyllactotetraose. Thirty-two of 37 well- to moderately-differentiated adenocarcinomas and all cystadenocarcinomas were positive for CA 50. The staining was most intense in the apical border of the cells, and in the intraluminal mucus. The number of positive cells was smaller in poorly differentiated adenocarcinomas and only occasional cells were stained in anaplastic carcinomas. In acute and chronic pancreatitis small terminal ducts, centro-acinar cells and some large ducts stained for CA 50. In normal pancreas only a few small terminal ducts were CA-19-9-positive, whereas both ducts and centro-acinar cells were C-50-positive. Normal pancreatic tissue adjacent to carcinoma usually stained more strongly for CA 50 than the carcinoma, whereas the opposite was true for CA 19-9. Eight out of 11 CA-19-9-negative carcinomas were CA-50-positive. Serous cystadenomas and malignant islet-cell tumors were focally positive for CA 50, but negative for CA 19-9. It seems apparent that the C 50 antibody reacts with another determinant than sialylated Lewisa in CA-19-9-negative specimens, serous cystadenomas and malignant islet-cell tumors. Serum CA 50 and CA 19-9 levels were determined in 29 patients with pancreatic cancer. The sensitivity was similar for both markers (76%), and there was a positive correlation between the serum levels. However, there was no correlation between the serum levels and the histological expression of the CA 50 and CA 19-9 antigens.     

Immunohistochemistry of human gastrointestinal cancer-associated antigen detected by monoclonal antibody PA 8-15

A murine monoclonal antibody (MAb), PA 8-15, was produced against a newly established human pancreatic adenocarcinoma cell line, SUIT-2. With the avidin-biotin immunoperoxidase technique, PA 8-15 MAb reacted strongly with 27 of 28 formalin-fixed paraffin-embedded pancreatic adenocarcinoma tissues. All six gall bladder carcinomas and all nine biliary tract carcinomas also showed positive reactions. In addition, PA 8-15 MAb reacted with gastric carcinomas (6/10), colorectal carcinomas (7/11), and some other primary adenocarcinomas. The distribution of PA 8-15 antigen on the same tissues of pancreatic cancer was different from those of CA 19-9 and DU-PAN-2 antigens and CEA. PA 8-15 MAb stained only the epithelium of the pancreatic duct, gall bladder and bile duct in normal adult tissues, and some normal fetal glandular epithelial cells. However, PA 8-15 MAb was not reactive with inflammatory or benign tumors of the digestive system except for the epithelium, as was seen in normal adults. Reactivity of PA 8-15 MAb with tissue specimens largely disappeared after treatment with neuraminidase, while oxidation with periodate or trypsin digestion did not alter the staining intensity, indicating that antigenic determinants may be at least partly of sialylated carbohydrate nature. These results suggest that PA 8-15 MAb detects a new oncofetal antigen in gastrointestinal cancers, especially of the pancreatico-biliary tract.     

Immunohistochemistry of Human Gastrointestinal Cancer-associated Antigen Detected by Monoclonal Antibody PA 8-15

A murine monoclonal antibody (MAb), PA 8-15, was produced against a newly established human pancreatic adenocarcinoma cell line, SUIT-2. With the avidin-biotin immunoperoxidase technique, PA 8-15 MAb reacted strongly with 27 of 28 formalin-fixed paraffin-embedded pancreatic adenocarcinoma tissues. All six gall bladder carcinomas and all nine biliary tract carcinomas also showed positive reactions. In addition, PA 8-15 MAb reacted with gastric carcinomas (6/10), colorectal carcinomas (7/11), and some other primary adenocarcinomas. The distribution of PA 8-15 antigen on the same tissues of pancreatic cancer was different from those of CA 19-9 and DU-PAN-2 antigens and CEA. PA 8-15 MAb stained only the epithelium of the pancreatic duct, gall bladder and bile duct in normal adult tissues, and some normal fetal glandular epithelial cells. However, PA 8-15 MAb was not reactive with inflammatory or benign tumors of the digestive system except for the epithelium, as was seen in normal adults. Reactivity of PA 8-15 MAb with tissue specimens largely disappeared after treatment with neuraminidase, while oxidation with periodate or trypsin digestion did not alter the staining intensity, indicating that antigenic determinants may be at least partly of sialylated carbohydrate nature. These results suggest that PA 8-15 MAb detects a new oncofetal antigen in gastrointestinal cancers, especially of the pancreatico-biliary tract.     

Gastrointestinal cancer-associated antigen CA 19-9 in histological specimens of pancreatic tumours and pancreatitis

The expression of the gastrointestinal cancer associated antigen CA 19-9, defined by the monoclonal antibody 1116 NS 19-9, was studied by immunoperoxidase staining in routine formalin-fixed, paraffin-embedded tissue sections from normal pancreata, pancreata with pancreatitis and from benign and malignant pancreatic neoplasms. The formalin-fixed specimens were treated with pepsin, which enhanced the staining intensity. Eighty-five per cent of well to moderately differentiated adenocarcinomas were positive. The staining was most intense in the apical border of cells lining the lumina of malignant glands, and in mucus inside the lumina, but cytoplasmic staining was also seen. In poorly differentiated adenocarcinomas the number of positive cells was smaller and in anaplastic carcinomas only occasional cells were stained. All mucinous cystadenomas and cystadenocarcinomas stained intensely, whereas serous cystadenomas, and all benign and malignant islet cell tumours were negative. Ducts in chronic pancreatitis and in normal pancreata were positive in 96% and 79%, respectively, but the staining was focal and usually weaker than in carcinomas. In acute pancreatitis (92% positive) the staining was more intense, and the CA 19-9 expression was seen predominantly in small terminal ducts and in centroacinar cells. There was an apparent correlation between the degree of differentiation of the ductal adenocarcinomas and the expression of CA 19-9, whereas the correlation between tissue expression and serum levels of CA 19-9 was poor.     

Relationship of carbohydrate antigen 19-9 and Lewis antigens in pancreatic cancer

Carbohydrate antigen (CA) 19-9 identified by a murine monoclonal antibody against a colorectal carcinoma antigen is thought to be a sialylated Lewis (Le)a blood group antigen and occurs in high concentration in serum of patients with pancreatic carcinoma. This study was designed to identify the relationship between Lewis antigens and CA 19-9 in patients with pancreatic cancer. The following analyses were performed in 20 pancreatic cancer patients: Lea and Leb antigen phenotype in saliva (modified enzyme-linked immunosorbent assay) or on red cells (hemagglutination); CA 19-9 levels (radioimmunoassay) in serum; and CA 19-9 and Lea and Leb expression (immunoperoxidase assay) on tumor tissue. Lea-b- patients based on salivary phenotype failed to express CA 19-9 in tumor tissue and had normal or low levels of CA 19-9 (less than 37 units/ml) in serum (P = 0.0011, versus Lea+b- and Lea-b+ patients). Eighty-eight % of Lea+b- and Lea-b+ patients had elevated serum CA 19-9 levels (greater than 37 units/ml). All Lea+b- and Lea-b+ patients expressed both Lea and Leb antigens in tumor tissue. These results support the view that Lea-b- pancreatic cancer patients cannot manufacture CA 19-9. Surprisingly, Lea-positive patients express Leb antigen in tumor tissue; in this subgroup, Leb antigen may be a tumor-specific biomarker.     

Initial clinical evaluation of two murine IgG2a monoclonal antibodies for immunotherapy of gastrointestinal carcinoma

Eleven patients with advanced gastrointestinal (GI) carcinoma were entered in Phase I initial clinical trials with IgG2a antiGI carcinoma monoclonal antibodies (MAbs) GA733 (five patients) or CO19-9 (six patients). Infusion of MAb GA733 in doses greater than 30 mg was accompanied by mild and short-lasting GI toxicity. Infused MAb GA733 was bound to each patient's tumor tissue in vivo. MAb circulated in the blood for 10-25 days. All patients developed anti-mouse antibodies between 15 and 60 days post infusion. Furthermore, all but one patient raised anti-idiotypic antibodies against MAb GA733. Following administration of 10-600 mg of MAb CO19-9, no immediate or delayed toxicity symptoms were noted. Binding of infused MAb CO19-9 to tumor cells in vivo could not be detected in any of the six patients studied. The MAb circulated in the bloodstream between 5 and 12 days. Human anti-mouse antibody was detected in sera of three patients. None of the eleven patients treated with either MAb had anti-tumor responses in this Phase I clinical trial. The strong binding reactivity of MAb GA733 to tumors in vivo suggests the use of this MAb in cancer patients with less tumor burden to determine the tumoricidal efficacy of this antibody.     

Detection of a circulating tumor-associated antigen with a murine monoclonal antibody, LISA 101, selected by reversed indirect enzyme-linked immunosorbent assay

In the presence of a characterized monoclonal antibody recognizing a soluble molecule, additional monoclonal antibodies reactive with unknown antigenic determinants on the molecule can be easily selected by reversed indirect enzyme-linked immunosorbent assay. A novel murine monoclonal antibody, LISA 101, was selected by reversed indirect enzyme-linked immunosorbent assay against soluble antigens, which exist in sera and in pleural effusions derived from lung adenocarcinoma patients and which bear determinants recognized by the previously characterized murine monoclonal antibody KL-6. Antigenic determinants recognized by the LISA 101 antibody appear to be sialylated carbohydrate in nature and different from those recognized by previously reported monoclonal antibodies against sialylated carbohydrates, such as NS 19-9, FH-6, and KL-6, suggested by competitive inhibition assay and immunostaining of tissues. A circulating antigen, LISA 1-6, was detected by a bimonoclonal bideterminant assay using immobilized LISA 101 antibody and enzyme-labeled KL-6 antibody. It was found that serum LISA 1-6 levels were elevated in 63% (25 of 40) of patients with lung adenocarcinoma and in 92% (11 of 12) of patients with pancreatic carcinoma, but only in 6.5% (2 of 31) of patients with benign lung diseases and in 7.1% (1 of 14) of patients with pancreatitis. The present observations indicate that the LISA 1-6 antigen may serve as a new tumor marker for adenocarcinomas of the lung and the pancreas. Additionally, the reversed indirect enzyme-linked immunosorbent assay may be a widely applicable method for selecting new monoclonal antibodies against as yet unknown antigenic determinants on soluble molecules.     

Comparative study of CA242 and CA19-9 for the diagnosis of pancreatic cancer.

A comparative study of a new tumour marker, CA242, and CA19-9 was conducted with special reference to their diagnostic usefulness in pancreatic cancer. CA242 showed sensitivity similar to that of CA19-9 for overall cases and early cases (stage I tumour) of pancreatic cancer. For other malignancies, the positive rates of CA242 were lower than those of CA19-9 except for colorectal cancer. An important characteristics of CA242 was that it was only slightly and infrequently elevated in the sera of patients with benign diseases such as chronic pancreatitis, chronic hepatitis and liver cirrhosis. This characteristic was more apparent in the patients with benign obstructive jaundice, indicating that the serum level of this marker was scarcely affected by cholestasis. Using cut-off levels corresponding to a 90% specificity, the clinical results obtained with CA242 in the diagnosis of pancreatic cancer were similar to those obtained with CA19-9, except that CA19-9 was falsely negative in some patients with early-stage pancreatic cancer. These findings suggest the usefulness of this marker for screening pancreatic cancer in patients on their first hospital visit. However, CA242 was found to be influenced by the Lewis blood group system. This unfavourable result is attributed to the C241 catcher antibody of this assay system, which has almost the same epitope specificity as the C50 and the NS19-9 monoclonal antibodies. In conclusion, CA242 is superior to CA19-9 in diagnosing pancreatic cancer by virtue of its higher specificity.     

Conserved epitopes in human and mouse tissue-nonspecific alkaline phosphatase. Second report of the ISOBM TD-9 workshop.

A panel of 19 monoclonal antibodies (MAbs) against human tissue-nonspecific (liver/bone/kidney) alkaline phosphatase (TNAP) was obtained through the ISOBM TD-9 workshop. In the present study, the reactivity of these MAbs has been characterized against mouse TNAP. A mouse embryonic stem cell line, frozen sections of long bones, alkaline phosphatase extracted from mouse bone, and serum were used as the source of TNAP for individual assays. Each MAb was tested for immunoreactivity to mouse TNAP by Western blot analysis, immunohistochemistry and enzyme immunoassay. Antibodies 314 and 315 reacted strongly with mouse TNAP in Western blots, while all other antibodies were negative. By immunohistochemistry, antibodies 314, 315 and 333 produced strong positive staining using frozen sections, while antibody 334 was moderately positive. Enzyme immunoassays indicated that MAb 333 was also able to bind to serum TNAP. These antibodies represent very useful reagents to study the pathophysiological expression of TNAP in mouse tissues and in mouse serum.     

Tissue expression of the tumour associated antigen CA242 in benign and malignant pancreatic lesions. A comparison with CA 50 and CA 19-9

The expression of a novel tumour associated antigen CA 242, defined by the monoclonal antibody C 242, was studied by immunoperoxidase staining in formalin-fixed, paraffin-embedded tissue sections from normal pancreata, pancreata with pancreatitis and benign and malignant pancreatic neoplasms. The antigenic determinant of the C 242 antibody is a sialylated carbohydrate structure, related but chemically different from tumour marker antigens CA 19-9 and CA 50. Thirty-eight of 41 (93%) well to moderately differentiated ductal adenocarcinomas of the pancreas and all cystadenocarcinomas were positive for CA 242. The staining was most intense in the apical border of the cells, and in the intraluminal mucus. Only two out of seven poorly differentiated adenocarcinomas stained, and the number of positive cells was smaller than in well differentiated carcinomas. Only occasional cells were stained in one out of five anaplastic carcinomas. Part of large ducts were positive in 91% (21/23) specimens of chronic pancreatitis. In acute pancreatitis small terminal ducts, centro-acinar cells and some large ducts stained for CA 242. In normal pancreas only a few small terminal ducts were CA 242 positive. Carcinomas always stained more strongly for CA 242 than normal pancreatic tissue adjacent to the carcinoma. The results of CA 242 are compared with those of tumour marker antigens CA 50 and CA 19-9. Serum CA 242 levels were determined in 23 of the patients with pancreatic cancer using a fluoroimmunoassay. Fifteen (65%) patients had an elevated value. There was no clear-cut correlation between the serum levels and the immunohistochemical expression of the CA 242 antigen. The expression of CA 242 in pancreatic tissue resembles that of CA 50 and is similar to CA 19-9. The antigen is expressed in serum of many patients with pancreatic cancer and, therefore, is a potential candidate for a serum tumour marker.     

Importance of pH in defining the specificity and clinical utility of monoclonal antibodies--an evaluation of two anti-CA 19-9 monoclonal antibodies

The effect of pH on the binding characteristics of monoclonal antibodies against tumor associated antigens has been studied, using anti-CA 19-9 monoclonal antibodies as an example. The 1116-NS-19-9 monoclonal antibody is used in several commercially available two-step sandwich IRMAs for the measurement of the CA 19-9 antigen in cancer patient sera (Centocor CA 19-9 RIA, Malvern, PA, U.S.A., or similar kits by Centocor licensees). The B25.10 monoclonal antibody is in use in the Truquant GITM RIA (Biomira Inc., Edmonton, Alberta, Canada), a competitive inhibition assay measuring the CA 19-9 antigen. We determined the Ka value of the B25.10 and the 1116-NS-19-9 antibodies at pH 4.5 and 7.3 on a solid phase coated with CA-19-9 bearing mucin. The 1116-NS-19-9 antibody had a Ka value of 4.1 x 10(8) at pH 4.5 and approximately 0.3 x 10(8) at pH 7.3. The Ka value of B25.10 was in the range of 0.7-4.1 x 10(9) at either pH, but somewhat lower at pH 4.5. At pH 4.5 (the pH optimum for binding of 1116-NS-19-9 to the CA 19-9 antigen Del Villano, B.C., 1984]) the binding of 125I-labeled B25.10 to the solid phase was comparably inhibited by 1116-NS-19-9 and B25.10. However, at neutral pH (pH 7.2) the apparent affinity of the 1116-NS-19-9 antibody for the CA 19-9 antigen is significantly diminished [Del Villano, B.C., 1984] while that of B25.10 is slightly higher. Consequently, the ability of the 1116-NS-19-9 to inhibit the binding of the B25.10 antibody to the CA 19-9 solid phase is greatly reduced in the physiological pH range. The consequences of these findings for in vivo applications are discussed.     

Characterization of CA 19-9 bearing mucins as physiological exocrine pancreatic secretion products

The monoclonal antibody CA 19-9 reacts with a carbohydrate epitope (sialylated lacto-N-fucopentaose II), which was shown to be part of a ganglioside extracted from a colon carcinoma cell line as well as of a mucin isolated from gastrointestinal tract tumor patients' sera. Recently, when we compared CA 19-9 levels in pancreatic juices and corresponding serum samples from a large group of patients, we showed the high serum values to be indicative solely for a malignant disease. In contrast, the overall high CA 19-9 content in pancreatic juices from all diagnostic groups raised the question about the antigenic moieties in these samples. By means of thin layer chromatography of glycolipids with subsequent antibody overlay, gel chromatography, and density gradient analysis, we found only the mucin form in all sources investigated. Thus we conclude that the discrimination potential of the CA 19-9 assay in serum is based on an altered secretion or distribution in pancreatic tumors.     

Purification and composition of a novel gastrointestinal tumor-associated glycoprotein expressing sialylated lacto-N-fucopentaose II (CA 19-9)

Monoclonal antibody 1116NS 19-9 (Mab 19-9) exhibits selective reactivity with human gastrointestinal carcinomas and recognizes a carbohydrate determinant (CA 19-9) defined as a sialylated lacto-N-fucopentaose II. A scheme was devised for the purification of a human gastrointestinal tumor-associated glycoprotein antigen expressing CA 19-9 from colorectal carcinoma cell line SW1116 culture media in high yield. The key steps in the purification were immunoaffinity column chromatography with Mab 19-9 followed by reduction and alkylation of the specifically bound proteins in the presence of 6 M guanidine hydrochloride and a second Mab 19-9 immunoaffinity fractionation. The purified CA 19-9 containing glycoprotein ran as a single band on sodium dodecyl sulfate-polyacrylamide gradient gels with an apparent molecular mass of 210 kilodaltons. In the absence of detergents, this purified glycoprotein apparently reassociated to form aggregates of 600-2000 kilodaltons molecular mass as determined by size-exclusion chromatography. Amino acid analysis of CA 19-9 containing glycoprotein revealed that serine, threonine, and proline together accounted for greater than 35% of the amino acid residues, consistent with a mucin-like structure for the protein. Carbohydrate compositional analysis, however, was in contrast to a typical mucin with a fucose:mannose:galactose:N-acetylgalactosamine: N-acetylglucosamine:N-acetylneuraminic acid molar ratio of 4:1:12:2.5:5:5. The presence of both N-acetylgalactosamine and mannose suggested that both O- and N-linked oligosaccharides may exist on CA 19-9 containing glycoprotein. Protein and carbohydrate analyses indicated that this novel tumor-associated glycoprotein was 85% carbohydrate by weight. This purification procedure may be applicable to the isolation of other epithelial tumor-associated antigens.     

Representation of epitopes on colon-specific antigen-p defined by monoclonal antibodies

Colon-specific antigen-p (CSAp) is a large molecular-sized protein restricted to normal and neoplastic gastrointestinal tissues and to some mucinous ovarian tumors. Murine monoclonal antibodies (MAbs) were raised against CSAp that was affinity purified with goat polyclonal antibodies from GW-39 human colonic carcinoma xenografts or against the CSAp-producing colon cancer cell line SW-948. Two of the MAbs, designated Mu-2 and Mu-4, recognized a CSAp determinant containing sialic acid, and this epitope was also expressed on bovine submaxillary mucin (BSM). Blocking experiments demonstrated that the Mu-2 and Mu-4 MAbs recognized different determinants. A third MAb, Mu-3, did not cross-react with BSM, but unlike Mu-2 and Mu-4, it did react with human saliva. Reactivity of Mu-3 with saliva did not correlate with major blood group and Lewis-related secretory blood group substances in saliva. This reactivity was not related to sialylated Lewis activity. The fourth antibody, Mu-1, appeared to react with a conformational determinant since its epitope was destroyed by heat treatment or thiol reduction. Enzyme immunoassays have demonstrated that all four epitopes may be expressed on one molecular species.     

Immunohistochemical heterogeneity of type 1 blood group antigen expressions in testicular germ cell tumors

The immunohistochemical expression of type 1 blood group antigens (type 1 BGAs) was analyzed for 30 cases of testicular germ cell tumors (TGCTs), using monoclonal antibodies against DU-PAN-2, CA19-9, Lewis(a) (Le(a)), and Lewis(b) (Le(b)). DU-PAN-2 was expressed very frequently in all of the embryonal carcinomas (ECs). CA19-9 expression was demonstrated in 53% of ECs, but the number of positive cells was generally smaller than that for DU-PAN-2. CA19-9-negative ECs tended to show a higher number of DU-PAN-2-positive cells compared to CA19-9-positive ECs, and ECs in which DU-PAN-2 was more strongly expressed showed a relatively frequent expression of CA19-9. In 36% of seminomas and 56% of yolk sac tumors (YSTs), DU-PAN-2 was weakly expressed, and the positive cells were few in number. Little or no expression of CA19-9 was demonstrated in seminomas and YSTs. Regarding Le(a) and Le(b), the expressions were found to be limited to teratomas at a frequency of 57% and 86%, respectively, with the exception of one EC positive for Lea and one YST positive for Leb. Eighty-six percent of teratomas showed expressions of DU-PAN-2 and CA19-9. DU-PAN-2 was also seen in some intratubular malignant germ cells. The antibodies used were all negative for choriocarcinomas, syncytiotrophoblastic giant cells, and normal testicular tissues. The antigen expressions were predominantly observed on the surface of tumor cells developing luminal structures. In conclusion, although CA19-9 was relatively specific for ECs, it should be emphasized that ECs were rather characteristic of extensive DU-PAN-2 expression. Particularly in CA19-9-negative ECs, a combined analysis of DU-PAN-2 and CA19-9 would be helpful in confirming the histopathologic diagnosis of TGCTs. The clinical significance of DU-PAN-2 in ECs as a tumor marker remains to be clarified. Le(a) and Le(b) expressions were thought to be related to the differentiation or maturation rather than to the malignant transformation in TGCTs.     

Cancer-associated tumour markers CA 19-9 and CA-50 in patients with pancreatic cancer with special reference to the Lewis blood cell status

Monoclonal antibodies 19-9 and C-50 were used to assay the cancer associated tumour antigens CA 19-9 and CA-50 in plasma from patients with confirmed pancreatic cancer, and related to the blood group and Lewis blood cell status. The plasma expressions of CA 19-9 or CA-50 were similar, including cases where the patients had Lewis phenotype Le (a-b-). However, analyses of both the tumour antigens could be used to differentiate the presence of cancer from its absence in Le (a-b-) individuals. The findings indicate that the targets for the monoclonal antibodies 19-9 and C-50 are similar. The practical implications of these findings are discussed.     

Clinical evaluation of combined use of CEA, CA19-9 and CA50 in the serum of patients with pancreatic carcinoma

CEA, CA19-9 and CA50 are tumour-associated antigens defined by monoclonal antibodies that have been raised against adenocarcinoma cell lines, but no single antibody is specific for the detection of pancreatic malignancy. The aim of this study was to determine whether the combined use of CEA, CA19-9 and CA50 would improve diagnostic accuracy. An immunoradiometric assay was used for the detection of CEA and CA19-9 and the Delfia system for CA50. Serum was collected from 65 normal subjects, 16 with pancreatitis and 28 with pancreatic carcinoma. Of the 28 cancer patients, 24 (85%) had a CA19-9 level above 46 mu/ml, 26 (92%) had a CA50 level above 21 mu/ml and 10 (37%) had a CEA level above 7 ng/ml. Multivariant discriminant analysis on the combined antibodies showed that 96% of the malignant group, 13% of the pancreatitis group and 11% of the normal group were positive, with an overall correct classification of 91% into the three groups (multivariant discriminant analysis P less than 0.05). Thus the combined use of CEA, CA19-9 and CA50 improves diagnostic accuracy in differentiating benign from malignant disease of the pancreas.     

Clinical usefulness of three monoclonal antibody-defined tumor markers: CA 19-9, CA 50, and CA 125

This article reviews the clinical usefulness of three monoclonal antibody-defined tumor markers: CA 19-9 or GICA, CA 50, and CA 125. These markers have been regarded as worthwhile tools for diagnosis and monitoring the management of patients with cancers in selected sites. The CA 19-9 test in combination with the CEA test is a useful adjunct for staging in some advanced cases and for monitoring therapy in the majority of patients with carcinoma of the stomach. Sensitivity of these assays performed concurrently is comparable to CEA alone in colorectal carcinoma. The CA 19-9 test alone is useful for staging and monitoring management of patients with carcinoma of the pancreas. In colorectal carcinoma the CA 19-9 test is redundant because of significantly lower sensitivity than that of the CEA assay; the latter remains the test of choice. The CA 50 test per se is redundant since the CA 19-9 antigen is the target for both the C50 MAb and the NS 19-9 MAb. The CA 125 test contributes to staging and is a useful adjunct for monitoring management of patients with non-mucinous carcinomas of the ovary. If positive after initial surgery and chemotherapy, this test provides evidence of the presence of residual or metastatic tumor and thus may obviate the need for second-look surgery. These conclusions are based on a review of recent relevant publications as well as on our own results obtained from preoperative evaluation and postoperative follow-up of about 600 patients with cancers in relevant sites.     

Potentiation of tumor lysis by a bispecific antibody that binds to CA19-9 antigen and the Fc gamma receptor expressed by human large granular lymphocytes

Murine monoclonal antibody therapy of human cancer rarely induces clinical responses. Antibody-induced cellular infiltrates rarely accumulate at sites of tumor, even in clinically responding lesions. Thus, the ability of these antibodies to promote host effector cell-mediated lysis of tumor via antibody-dependent cellular cytotoxicity (ADCC) has not been harnessed by existing treatment approaches. One potential explanation is that ADCC requires binding of antibody Fc domains to cellular Fc gamma receptors, and therapeutically administered murine antibodies must compete with vast excesses of human IgG for Fc gamma receptor occupancy. Chemically linked antibody heteroconjugates that bind selected target and effector cell structures via distinct Fab portions can mediate lysis of malignant cells in vitro in the presence of human serum. This approach addresses a potentially major obstacle to antibody therapy. Production of bispecific monoclonal antibodies with similar specificities and superior in vivo biodistribution characteristics would thus have potential clinical applications. We have prepared and purified a bispecific, monovalent monoclonal antibody and evaluated its in vitro effects. The IgG1-secreting hybridoma line 3G8 (alpha-human Fc gamma R III) was fused with the hybridoma line CA19-9, which produces an IgG1 antibody that binds to a glycoprotein shed by gastrointestinal cancers. Multiple clones with bispecific binding properties were identified. CA19-9 x 3G8 clonal supernatants and purified antibody, but not the parent antibodies, efficiently mediated specific in vitro lysis of cells of the SW948 line by human large granular lymphocytes (LGLs). Human serum-resistant target cell lysis augmentation at low effector:target ratios was seen using picogram amounts of antibody. In contrast, the IgG2 alpha variant of CA19-9, which also promotes ADCC by LGLs, was unable to augment lysis of SW948 cells when effectors were preincubated with human serum. This bispecific, monovalent monoclonal antibody is an efficient promoter of the anti-tumor effects of LGLs in physiological concentrations of human serum. In vivo models that evaluate treatment efficacy and promotion of inflammatory tumor infiltrates by bispecific monoclonal antibodies are required to assess the therapeutic potential of these novel constructs.