Autoantibodies against the tumour-associated antigen GA733-2 in patients with colorectal carcinoma

The tumour-associated antigen (TAA) GA733-2 is expressed as a non-secreted surface molecule on the majority of human colorectal carcinoma cells. The antigen has been used as a target for passive and active immunotherapy during the last decade. To determine the incidence of autoantibodies against this antigen, sera from 1068 patients with colorectal carcinoma were analysed for naturally occurring IgG antibodies against the baculovirus-produced GA733-2E protein. A total of 14.5% of the patients had IgG antibodies against the antigen. In 519 patients, sera were collected at the time of diagnosis and 15% of those patients had anti-GA733-2E IgG antibodies. There was a tendency to a higher frequency of patients with antibodies among those in the advanced Dukes stages: 11% in stage A and 32% in stage D respectively (P = 0.06). Antibodies could be detected for up to 10 years after the diagnosis. Patients with Crohn's disease or colitis ulcerosa (n = 20) did not elicit anti-GA733-2E antibodies. No healthy control donor (n = 45) had detectable antibodies against the antigen. The specificity of GA733-2E-reactive serum IgG was indicated by significant inhibition of mAb17-1A (originally used to define GA733-2) binding to the GA733-2E antigen. Sera of positive patients bound to the GA733-2-expressing human colorectal carcinoma cell line, SW948. No significant correlation was found between the presence of antibodies and survival in the present patient population. However, the high incidence of autoantibodies against this tumour antigen in colorectal carcinoma patients confirms its antigenicity in humans and supports the use of the GA733-2 antigen as a target for immunotherapy. Received: 25 May 1998 / Accepted: 26 November 1998     

Oligomeric state of the colon carcinoma-associated glycoprotein GA733-2 (Ep-CAM/EGP40) and its role in GA733-mediated homotypic cell-cell adhesion

The GA733-2 antigen (GA733) is a homotypic calcium-independent cell adhesion molecule (CAM) present in most normal human epithelial cells and gastrointestinal carcinomas. Because oligomerization of some CAMs regulates cell adhesion and signal transduction, the correlation between GA733 oligomeric state and cell-cell adhesion was investigated. Sedimentation equilibrium studies showed that full-length (-FL) GA733 exists as dimers and tetramers in solution, whereas the GA733 extracellular domain (-EC) is a monomer. The Kd of GA733-FL is less than 10 nm for the monomer-dimer association, whereas the dimer-tetramer association is about 1000-fold weaker (Kd approximately 10 microm). Chemical cross-linking of purified GA733-FL in solution resulted in a major product corresponding to GA733 dimers, and minor amounts of trimers and tetramers. However, GA733-EC cross-linked under the same conditions was consistently a monomer. Chemical cross-linking of dissociated colon carcinoma cells produced predominantly GA733 dimers, whereas cross-linking of cells in monolayers yielded some tetramers as well. GA733-FL retained its cell-cell adhesion function as shown by inhibition of cell aggregation, whereas monomeric GA733-EC was inactive. These data show that GA733 exists predominantly as high affinity noncovalent cis-dimers in solution and on dissociated colon carcinoma cells. The lower affinity association of dimers to form tetramers is most likely the head-to-head interaction between GA733 cis-dimers on opposing cells that represents its cell-cell adhesion activity.     

Determination of disulfide bond assignments and N-glycosylation sites of the human gastrointestinal carcinoma antigen GA733-2 (CO17-1A, EGP, KS1-4, KSA, and Ep-CAM)

The GA733-2 antigen is a cell surface glycoprotein highly expressed on most human gastrointestinal carcinoma and at a lower level on most normal epithelia. It is an unusual cell-cell adhesion protein that does not exhibit any obvious relationship to the four known classes of adhesion molecules. In this study, the disulfide-bonding pattern of the GA733-2 antigen was determined using matrix-assisted laser desorption/ionization mass spectrometry and N-terminal sequencing of purified tryptic peptides treated with 2-[2'-nitrophenylsulfonyl]-3-methyl-3-bromoindolenine or partially reduced and alkylated. Numbering GA733-2 cysteines sequentially from the N terminus, the first three disulfide linkages are Cys1-Cys4, Cys2-Cys6, and Cys3-Cys5, which is a novel pattern for a cysteine-rich domain instead of the expected epidermal growth factor-like disulfide structure. The next three disulfide linkages are Cys7-Cys8, Cys9-Cys10, and Cys11-Cys12, consistent with the recently determined disulfide pattern of the thyroglobulin type 1A domain of insulin-like growth factor-binding proteins 1 and 6. Analysis of glycosylation sites showed that GA733-2 antigen contained N-linked carbohydrate but that no O-linked carbohydrate groups were detected. Of the three potential N-linked glycosylation sites, Asn175 was not glycosylated, whereas Asn88 was completely glycosylated, and Asn51 was partially glycosylated. These data show that the extracellular domain of the GA733-2 antigen consists of three distinct domains; a novel cysteine-rich N-terminal domain (GA733 type 1 motif), a cysteine-rich thyroglobulin type 1A domain (GA733 type 2 motif), and a unique nonglycosylated domain without cysteines (GA733 type 3 motif).     

Expression of a recombinant chimeric protein of human colorectal cancer antigen GA733-2 and Fc fragment of antibody using a replicating vector based on Beet curly top virus in infiltrated Nicotiana benthamiana leaves

We describe expression and characterization of recombinant human colorectal cancer antigen GA733-2 fused to Fc fragment of antibody (GA733-2-Fc) using a replicating vector based on Beet curly top virus in infiltrated Nicotiana benthamiana leaves. Recombinant GA733-2-Fc/KDEL with a molecular mass of ~68?kDa was transiently expressed. The level of expression of GA733-2-Fc with ER retention signal KDEL (GA733-2-Fc/KDEL) in the expression vector system was 0.96% of total soluble proteins. Recombinant GA733-2-Fc/KDEL was purified using an affinity chromatography. Mice immunized with recombinant GA733-2-Fc/KDEL mounted a strong GA733-2-Fc/KDEL-specific serum antibody response. Vaccination of plant-derived recombinant GA733-2-Fc/KDEL regressed tumor volumes in BALB/c mice. The population of activated-T and NK-T cells increased notably in lymph node, spleen, and tumor-infiltrating lymphocytes derived from the tumor-regressed mice. Taken together, recombinant GA733-2-Fc/KDEL expressed in plants can be used as an effective experimental immunogen for research in cancer vaccine development.     

N-acetyltransferase 2 gene polymorphism in patients with colorectal carcinoma

The acetylation polymorphism is a common inherited variation in human drug and carcinogen metabolism. Because N- acetyltransferase (NAT2) is important for the detoxification and/or bioactivation of drugs and carcinogens, polymorphisms of this gene have important implications in therapeutics of and susceptibility to cancer. In this study, NAT2 genotype (NAT2*5A (C(481)T), NAT2*6A (G(590)A), NAT2*7A/B (G(857)A)) and NAT2*14A (G(191)A) and phenotype were determined in 125 patients with colorectal carcinoma and 82 healthy control in Mersin, a city located in the southern region of Turkey. Isolation of the subjects' DNA was performed by using a highly purified PCR template preparation kit/(Roche Diagnostics cat. no: 1 796 828) and the NAT2 polymorphism was detected using real-time PCR (Roche Diagnostics, GmbH, Mannheim, Germany). According to this study high protein intake is associated with the increased risk for the development of colon cancer (OR = 1.73; 95% CI, 1.10-3.07). Although only NAT2*14A fast type was associated with increased risk in patients with colorectal carcinoma (OR = 3.03; 95% CI, 1.56-5.86), when a high protein diet was considered, NAT2*7A/B fast genotype was also found to be associated with an increased risk (OR = 2.06, 95% CI for NAT2*7A/B, 1.10-3.86; OR = 2.65; 95% CI, 1.29-5.46 for NAT2*14A). Smoking status did not differ between the control and patient groups. Our data suggest that exposure to carcinogens through consumption of a high-protein diet may increase the risk of colorectal carcinoma only in genetically-susceptible individuals.     

Immunogenicity of the carcinoembryonic antigen derived peptide 694 in HLA-A2 healthy donors and colorectal carcinoma patients

Carcinoembryonic antigen (CEACAM5) is commonly overexpressed in human colon cancer. Several antigenic peptides recognized by cytolytic CD8+ T-cells have been identified and used in colon cancer phase-I vaccination clinical trials. The HLA-A*0201-binding CEA_694–702 peptide was recently isolated from acid eluted MHC-I associated peptides from a human colon tumor cell line. However, the immunogenicity of this peptide in humans remains unknown. We found that the peptide CEA_694–702 binds weakly to HLA-A*0201 molecules and is ineffective at inducing specific CD8+ T-cell responses in healthy donors. Immunogenic-altered peptide ligands with increased affinity for HLA-A*0201 were identified. Importantly, the elicited cytolytic T lymphocyte (CTL) lines and clones cross-reacted with the wild-type CEA_694–702 peptide. Tumor cells expressing CEA were recognized in a peptide and HLA-A*0201 restricted fashion, but high-CEA expression levels appear to be required for CTL recognition. Finally, CEA-specific T-cell precursors could be readily expanded by in vitro stimulation of peripheral blood mononuclear cell (PBMC) from colon cancer patients with altered CEA peptide. However, the CEA-specific CD8+ T-cell clones derived from cancer patients revealed low-functional avidity and impaired tumor-cell recognition. Together, using T-cells to demonstrate the processing and presentation of the peptide CEA694-702, we were able to corroborate its presentation by tumor cells. However, the low avidity of the specific CTLs generated from cancer patients as well as the high-antigen expression levels required for CTL recognition pose serious concerns for the use of CEA694-702 in cancer immunotherapy.     

Characterization of the DNA-binding protein antigen Ku recognized by autoantibodies from patients with rheumatic disorders

We have characterized the biochemical nature of the Ku protein, the antigen recognized by autoantibodies from certain patients with scleroderma-polymyositis overlap syndrome. From extracts of HeLa cells labeled with [32P]orthophosphate, anti-Ku antibodies precipitated a high molecular weight nucleic acid identified as DNA because of sensitivity to DNase I and resistance to RNase. From extracts of cells labeled with [35S] methionine, these antibodies precipitated two polypeptides of 70,000 and 80,000 Da. These proteins were purified using immunoaffinity column chromatography. In immunoblots most sera containing anti-Ku antibodies recognized both Ku proteins but one serum bound only to the 70,000-Da subunit. When nucleosomal segments of chromatin were used as antigen, anti-Ku antibodies precipitated dinucleosomes and larger forms of chromatin but not mononucleosomes. Thus, the Ku antigen is a novel DNA-binding protein that is at least partially exposed on nucleosomal segments of chromatin.     

Proteomic analysis of autoantibodies in patients with hepatocellular carcinoma

To detect autoantibodies that could be diagnostic markers for hepatocellular carcinoma (HCC), we analyzed serum autoantibodies comprehensively that showed immunoreactivity to proteins in tumor tissue obtained from patients with HCC. Fifteen paired samples of HCC tissue and corresponding nontumorous liver tissue as well as five normal liver tissue samples were used in the study. A combination of proteomics and SEREX (serologic analysis of recombinant cDNA expression libraries) technique was used. Tissue proteins were separated by 2-DE, transferred onto PVDF membranes, and immunoblotted with autologous sera. By comparing each immunoblot pattern, we identified four immunoreactive spots with stronger staining intensity in tumorous tissues than in corresponding nontumorous tissues and in normal liver tissues. Matched proteins on 2-DE gels were identified by LC-MS/MS. These immunoreactive proteins were heat shock 70 kDa protein 1 (HSP70), glyceraldehyde 3-phosphate dehydrogenase, peroxiredoxin, and manganese superoxide dismutase (Mn-SOD). In HCC sera, occurrences of autoantibodies against these proteins were 7/15 (46.7%), 5/15 (33.3%), 5/15 (33.3%), and 6/15 (40.0%), respectively, whereas 2/20 (10.0%), 7/20 (35.0%), 0/20 (0.0%), and 2/20 (10.0%) were in control sera. Immunoblot analysis using commercially available purified proteins was performed to confirm the specificity of autoantibodies. By statistical analysis, autoantibodies against HSP70, peroxiredoxin, and Mn-SOD showed significantly high-frequency immunoreaction in HCC sera. The three antibodies were considered patient-specific antibodies in HCC and may be candidate diagnostic biomarkers for HCC.     

Detection of a nucleolar 7-2 ribonucleoprotein and a cytoplasmic 8-2 ribonucleoprotein with autoantibodies from patients with scleroderma

In studies on antinucleolar antibodies in sera from 24 patients with scleroderma, an autoimmune disease, one serum, designated "anti-To", contained antibodies against a nucleolar 7-2 ribonucleoprotein and a novel cytoplasmic 8-2 ribonucleoprotein. The 7-2 and 8-2 RNAs are distinct RNAs with a pppG terminus. They are partially conserved between rat and human species and are present in distinct ribonucleoprotein particles. Eight sera contained antibodies that precipitated particles containing nucleolar U3 RNA; these antibodies appear to be directed against preribosomal particles containing U3 ribonucleoprotein, rather than the U3 ribonucleoprotein particles alone. All these ribonucleoproteins required proteins for antigenicity. These antibodies will be of use in studies on the structure and function of these novel small ribonucleoproteins.     

Immunohistochemical studies of colorectal carcinoma with a monoclonal antibody against carcinoembryonic antigen

Immunoperoxidase localization of carcinoembryonic antigen (CEA) was performed on tissue sections of colorectal carcinoma using a monoclonal antibody (MAb) against CEA. CEA has been demonstrated in 20 out of 22 rectum carcinomas (90.9%), in all of 23 colonic carcinomas, in none of 4 hyperplastic polyps and in 2 out of 6 adenomatous polyps (33.3%). CEA was found more often, and the intensity of the staining was stronger in well-differentiated carcinomas than in moderately and poorly differentiated carcinomas. No correlation was found between the presence of CEA in colorectal carcinoma and the stages of the disease. The mean values of serum CEA in patients with colorectal carcinoma and polyps with negative, weakly and strongly positive staining were 5.4 +/- 3.9 ng/ml, 28.3 +/- 23.8 ng/ml and 99.8 +/- 145.3 ng/ml respectively. Elevation of serum CEA occurred in 30 out of 39 (78.9%) cases with strongly positive CEA staining, in 4 out of 6 (66.7%) with weakly positive and in 1 out 9 (11.1%) with negative staining. A significant difference was found in serum CEA activity between the group with negative CEA staining and positive CEA staining (P less than 0.01). Our results suggest that the monoclonal antibody (MAb C27) can be used for the localization of CEA in conventionally prepared tissues of colorectal carcinomas by immunoperoxidase techniques for routine immunopathological diagnosis.     

Carcinoembryonic antigen gene and carcinoembryonic antigen expression in the liver metastasis of colorectal carcinoma.

The presence of the carcinoembryonic antigen (CEA) gene and CEA expression in the liver was tested to identify their possible roles in the liver metastasis of colorectal carcinoma. The CEA gene in the liver was identified by amplifying the CEA-specific N-terminal domain exon with digoxigenin-dUTP labeling in 16 colorectal carcinomas with liver metastases. Next, CEA expression was tested by immunostaining using the anti-CEA monoclonal antibody (T84.66, ATCC). Liver tissues from 13 stomach cancer patients and 12 colorectal cancer patients without liver metastasis were also tested as control groups. Three grades (<25%, 25-50%, and 50%< or =) were given according to the proportion of positive cells. The CEA gene was amplified in the metastatic tumor cells of the liver (2.6 +/- 0.2, mean grade +/- SEM) and their surrounding hepatocytes (1.5 +/- 0.2) in all cases. CEA expression was found in all metastatic tumor cells and 14 cases of the surrounding hepatocytes. Among the control groups, the CEA gene of the hepatocytes was found in 9 cases each of the colorectal and the stomach cancers that did not exhibit CEA expression. The level of serum CEA was related with the numbers and volume of liver metastases, but not with CEA expression in tumor cells and surrounding hepatocytes. The CEA gene in the metastatic tumor cells, not in the hepatocytes, was closely associated with CEA expression in the surrounding hepatocytes (p<0.01). Although the precise mechanism of CEA gene regulation in hepatocytes remains to be proven, the CEA gene in the metastatic tumor of the liver seems to affect CEA expression in the surrounding hepatocytes facilitating liver metastasis in colorectal carcinoma.     

Detection of autoantibodies to the diabetes-associated antigen IA-2 by a sensitive enzyme-linked immunosorbent assay.

The tyrosine phosphatase like protein IA-2 is an important autoantigen in insulin-dependent diabetes mellitus (type 1 diabetes). Autoantibodies to IA-2 (IA-2A) are present in the serum of patients with type 1 diabetes even before the onset of the disease. Previously, we reported on a radioimmune assay to detect IA-2A, using E. coli-derived 125I-labelled IA-2 as antigen. Although this assay could be shown to be equivalent to the common reference method for IA-2A detection (radioligand assays using in vitro synthesised 35S-methionine labelled antigen), the disadvantages of both assays with respect to synthesis and handling of the radioactive antigen limit their use in routine laboratories. In this study, we have evaluated a non-radioactive enzyme-linked immunosorbent assay (ELISA) for the simple detection of IA-2A. We report on an ELISA where the biotinylated intracytoplasmic part of IA-2 (IA-2ic) is captured on streptavidin-coated plates. The sensitivity of the ELISA was similar to the validated radioligand assay, as it detected 47 of 69 (69%) patients with type 1 diabetes as compared to 46 of 68 (67 %) with the reference method for IA-2A detection (radioligand assays using in vitro synthesised 35S-methionine labelled antigen). Only 2 of 50 (4%) patients with autoimmune thyroid disease and 1 of 114 (1 %) healthy controls were detected in the ELISA, confirming specificity. There was a significant correlation between the ELISA and the radioligand assay (r = 0.64, p<0.001). We conclude that this ELISA is suitable to detect IA-2A in the serum of patients with type 1 diabetes with a similar sensitivity and specificity to the radioligand assay. This ELISA will allow rapid and simple measurement of IA-2A where the radioligand assay is inconvenient or not available.     

Irreversible repolarization of tumour-associated macrophages by low-Pi stress inhibits the progression of hepatocellular carcinoma

Numerous studies have shown the positive correlation between high levels of Pi and tumour progression. A critical goal of macrophage-based cancer therapeutics is to reduce anti-inflammatory macrophages (M2) and increase proinflammatory antitumour macrophages (M1). This study aimed to investigate the relationship between macrophage polarization and low-Pi stress. First, the spatial populations of M2 and M1 macrophages in 22 HCC patient specimens were quantified and correlated with the local Pi concentration. The levels of M2 and M1 macrophage markers expressed in the peritumour area were higher than the intratumour levels, and the expression of M2 markers was positively correlated with Pi concentration. Next, monocytes differentiated from THP-1 cells were polarized against different Pi concentrations to investigate the activation or silencing of the expression of p65, IκB-α and STAT3 as well as their phosphorylation. Results showed that low-Pi stress irreversibly repolarizes tumour-associated macrophages (TAMs) towards the M1 phenotype by silencing stat6 and activating p65. Moreover, HepG-2 and SMCC-7721 cells were cultured in conditioned medium to investigate the innate anticancer immune effects on tumour progression. Both cancer cell lines showed reduced proliferation, migration and invasion, as epithelial–mesenchymal transition (EMT) was inactivated. In vivo therapeutic effect on the innate and adaptive immune processes was validated in a subcutaneous liver cancer model by the intratumoural injection of sevelamer. Tumour growth was significantly inhibited by the partial deprivation of intratumoural Pi as the tumour microenvironment under low-Pi stress is more immunostimulatory. The anticancer immune response, activated by low-Pi stress, suggests a new macrophage-based immunotherapeutic modality.     

FMNL2 enhances invasion of colorectal carcinoma by inducing epithelial-mesenchymal transition

FMNL2 is a member of diaphanous-related formins that control actin-dependent processes such as cell motility and invasion. Its overexpression in metastatic cell lines and tissues of colorectal carcinoma has been associated with aggressive tumor development in our previous study. But its specific role in cancer is largely unknown. Here we report that FMNL2 is involved in epithelial-mesenchymal transition (EMT) maintenance in human colorectal carcinoma cells. A positive correlation between FMNL2 and vimentin expression and an inverse correlation between FMNL2 and E-cadherin expression were found in colorectal carcinoma cell lines and cancer tissues. Specific knockdown of FMNL2 led to an epithelial-state transition, confirmed by the cobblestone-like phenotype, upregulation of E-cadherin, α-catenin, and γ-catenin, and downregulation of vimentin, snail, slug. Loss of FMNL2 expression lowered the ability of TGF-β to induce cell invasion and EMT, as shown by morphology and the expression levels. Upregulation of vimentin, slug, snail, downregulation of E-cadherin and activation of receptor-Smad3 phosphorylation were observed in M5 and MDCK cells induced by TGF-β, whereas altered expression of these markers was not obvious in FMNL2-depleting M5 cells. High levels of activation of p-MAPK and p-MEK, but not p-PI3K and p-AKT, were observed in SW480/FMNL2+ cells compared with control cells. Treatment with U0126 could abrogate the activation of p-MAPK and p-MEK, whereas LY294002 treatment had no effect on the PI3K/AKT pathway. In conclusion, these findings identify a novel EMT and tumor promoting function for FMNL2, which is involved in TGF-β-induced EMT and colorectal carcinoma cell invasion via Smad3 effectors, or in collaboration with MAPK/MEK pathway.     

Clinical effects of monoclonal antibody 17-1A combined with granulocyte/macrophage-colony-stimulating factor and interleukin-2 for treatment of patients with advanced colorectal carcinoma

Granulocyte/macrophage-colony-stimulating factor (GM-CSF) has previously been indicated to enhance the therapeutic effect of the anti-colorectal carcinoma mAb17-1A as well as to augment in vivo immune effector functions. In vitro interleukin-2 (IL-2) augmented GM-CSF-induced antibody-dependent cellular cytotoxicity, a mechanism considered to be of significance for the therapeutic effect of mAb. A treatment regimen was elaborated that combined mAb17-1A (400 mg at day 3 of a 10-day treatment cycle) with the simultaneous administration of GM-CSF (250 μmg/m² once daily) and IL-2 (2.4 × 10⁶ U/m² twice daily) for 10 days. The treatment cycle was repeated once a month. Twenty patients with advanced colorectal carcinoma were included in the study. One patient obtained a partial remission and 2 patients stable disease for 7 and 4 months respectively. The median survival time from the start of mAb therapy was 8 months. Owing to allergic reactions, the planned mAb17-1A dose had to be reduced by repeated infusions. At the fourth treatment cycle only 25% received the planned mAb dose. In 3 patients the GM-CSF and IL-2 dose was reduced because of side-effects. The subjective tolerability of the treatment was considered good or acceptable in more than 80% of the patients. The increment in white blood cell subsets induced by the cytokines decreased by increasing number of courses. This particular regimen did not augment the therapeutic effect of mAb17-1A anticipated from in vitro data but rather hampered the clinical effect of the antibody. The reason for this is not clear but a possibility might be the induction of immune suppression in vivo resulting from an impaired human anti-(mouse Ab) and anti-idiotypic antibody response as well as antibody-dependent cellular cytotoxicity, on the basis of a comparison of mAb17-1A/GM-CSF/IL-2- and mAb17-1A/GM-CSF-treated patients. Received: 25 February 1999 / Accepted: 15 July 1999     

Carcinoembryonic antigen and breast carcinoma antigen (CA 15.3) in preoperative staging and postoperative monitoring of patients with carcinoma of the breast

Serum levels of carcinoembryonic antigen (CEA) and breast carcinoma antigen (CA 15.3) were determined in patients with breast carcinoma: in 129 before initial surgical or nonsurgical treatment and in 134 afterwards. Before any initial treatment, CEA was elevated in 15% of patients with Stage IV disease and CA 15.3 was high in 11% with Stage III and 48% with Stage IV. While monitoring management active disease was associated with elevated serum CEA in 66% of the patients, with elevated CA 15.3 in 73% and with at least one of the markers elevated in 86%. Both tests had high specificity (93% and 98%). The rise in serum CEA and, even more so, of serum CA 15.3 roughly paralleled the increase in bulk of the tumor: from locoregional disease through metastases to the lungs, bones, lungs with bones, and liver. Decreases in the levels of serum CEA and CA 15.3 reflected response to therapy, increases in the level of at least one marker-treatment failure, and levels fluctuating above the normal range indicated stationary disease. During follow-up, the predictive value of a negative test (levels within the normal range), suggesting that the patient might be free of disease, was 61% for CEA alone, 67% for CA 15.3 alone, and 80% for the two tests combined. We conclude that an elevated serum level of only one of the markers was useful for staging, implying advanced disease. Determination of both markers jointly was useful for monitoring the effectiveness of the therapy and for follow-up aimed at detection of relapse.     

Detection by monoclonal antibody of carbohydrate antigen CA 50 in serum of patients with carcinoma.

A solid phase radioimmunoassay was devised for measuring the value of the carcinoma associated carbohydrate antigen CA 50 in serum based on the use of a specific monoclonal antibody (C 50). Samples of serum from 259 patients with carcinoma, 114 patients with other malignancies or inflammatory diseases, and 150 healthy controls were examined. Serum values of CA 50 exceeding the mean plus three standard deviations for control samples from blood donors were found in a high proportion of patients with colorectal adenocarcinomas (50% of those with early, localised tumours and 75% of advanced cases), other gastrointestinal carcinomas (69%), uterine cancer (75% of those with corporeal and 88% of those with cervical cancer), prostatic cancer (90%), lung cancer (52%), and breast, ovarian, kidney, and urinary bladder carcinoma (26-67%). The CA 50 values in samples from patients with inflammatory diseases, including ulcerative colitis, with rare exceptions (0-7%) were within the normal range, as were those in patients with various sarcomas and malignant melanoma. Measuring serum values of CA 50, which is evidently a generalised carcinoma associated antigen, may be useful in clinical research studies of the diagnosis, management, and prognosis of patients with different types of carcinoma.     

The role of serum carcinoembryonic antigen (CEA) in the management of patients with colorectal carcinoma: the experience of the Istituto Tumori of Milan.

CEA determination has attained an important role in the clinical management of patients with tumors of the colorectal tract. In this paper the experience of the Istituto Tumori of Milan is reviewed and the results are discussed. Three hundred and thirty-six patients were followed after curative resection of colorectal carcinoma. The follow-up period was 15 years, from January 1975 to December 1990 (global follow-up 1358 years). In the course of follow-up 136 patients developed recurrent disease. The number of CEA determinations for each patient ranged from 1 to 37 (mean 8, total 3330). CEA levels of presurgical patients were related to the clinical stage. Among patients who developed recurrences 61% showed an increase in CEA serum levels. In 200 patients with a negative follow-up we observed only 15 cases of false-positive results.