Oncofetal and other tumor-associated antigens of the human digestive system

Induction of tumor-specific T-cell responses by vaccination with tumor lysate-loaded dendritic cells in colorectal cancer patients with carcinoembryonic-antigen positive tumors

BACKGROUND

Dendritic cells (DCs) are the most effective antigen-presenting cells. In the last decade, the use of DCs for immunotherapy of cancer patients has been vastly increased. High endocytic capacity together with a unique capability of initiating primary T-cell responses have made DCs the most potent candidates for this purpose. Although DC vaccination occasionally leads to tumor regression, clinical efficacy, and immunogenicity of DCs in clinical trials has not been yet clarified. The present study evaluated the safety and effectiveness of tumor-lysate loaded DC vaccines in advanced colorectal cancer (CRC) patients with carcinoembryonic antigen (CEA) positive tumors.

RESULTS

Six patients HLA-A*0201-positive were vaccinated with autologous DCs loaded with tumor lysates (TL) together with tetanus toxoid antigen, hepatitis B, and influenza matrix peptides. Two additional patients were injected with DCs that were generated from their sibling or parent with one haplotype mismatch. All patients received the vaccines every 2 weeks, with a total of three intra-nodal injections per patient. The results indicated that DC vaccination was safe and well tolerated by the patients. Specific immune responses were detected and in some patients, transient stabilization or even reduction of CEA levels were observed. The injection of haplotype mismatched HLA-A*0201-positive DCs resulted in some enhancement of the anti-tumor response in vitro and led to stabilization/reduction of CEA levels in the serum, compared to the use of autologous DCs.

CONCLUSION

Altogether, these results suggest that TL-pulsed DCs may be an effective vaccine method in CRC patients. Elimination of regulatory mechanisms as well as adjustment of the vaccination protocol may improve the efficacy of DC vaccination.

[Pilot study with the monoclonal antibody IOR-C5 as a potential agent of radioimmunoscintigraphy in colorectal cancer]

IOR C-5 is a G1 immunoglobulin type intact murine monoclonal antibody (MAb) that was developed in the Center of Molecular Immunology in Havana City, Cuba. In immunohistochemical studies, this demonstrated a significant affinity for the epithelial tissues so that it was used in a pilot clinical study to perform a radioimmunoscintigraphy of the colorectal primary tumors and their locoregional recurrences. It was labeled with 99mTc using the Schwarz method, with a > 95% performance. Planar images of the chest, abdomen and pelvis were performed at 10 minutes, 4-6 hours and 18-24 hours post-injection in the anterior and posterior projections and the SPECT was performed 4-6 hours and 18-24 hours post-injection of 1.85 GBq 99mTC. This study has aimed to verify in vivo the capacity of ior-C5 MAb to accumulate in the malignant colorectal lesions. ior-C5 accumulated in 5 out of the 7 patients who were studied and who were suffering from colorectal cancer or in whom there was suspicion of recurrence. There was a negative case of primary tumors, which was an adenocarcinoma in situ in a tubular-papillary adenoma. The second case with a negative radioimmunoscintigraphy was a true negative case.

CONCLUSIONS

It can be concluded that even though the number of patients is quite low, ior-C5 fulfilled the expectations of recognizing the epitope expressed in colorectal tumors in an in vivo human environment.

A perspective of monoclonal antibodies: past, present, and future

In 1975, the development of the technique to produce monoclonal antibodies revolutionized the approach to cancer detection and therapy. Hundreds of monoclonal antibodies to the epitopes of tumor cells have been produced, providing more specific tools for probing the cellular elements of cancer. At the same time, these tools have disclosed greater complexity in the character of these cells and stimulated further investigation. Although there are antibodies to specific epitopes of neoplastic cells, this purity has not provided the improved detection and therapy of cancer first expected. Technical manipulations have provided limited improvement in results, but more sophisticated techniques, such as biologic response modifiers, may be required to attain clinical results that can be universally applied. The intense research in monoclonal antibodies and their application does offer promise that the goal of improved cancer detection and therapy will be forthcoming.

A comparison of monoclonal antibodies against distinct colon tumor-associated antigens in immunohistochemistry and in tumor localization

Monoclonal antibodies to colon/ovary tumor antigen (COTA), carcinoembryonic antigen (CEA), colon-specific antigen (CSA), and colon-specific antigen "protein" (CSAp) were evaluated for specificity, reactivity with normal tissues, and tumor localizations using athymic rats bearing xenografted human colon tumors. Radioiodine labeled anti-CSA and anti-COTA retained immunoreactivity and effectively localized the tumors; anti-CSAp retained immunoreactivity, but localized less effectively; and anti-CEA lost most of its immunoreactivity and localized poorly. Of the antibodies tested, anti-COTA showed potential for human colorectal tumor radiolocalization.

Tumor markers in carcinoma and premalignant states of the stomach in humans

Tissue sections taken from areas of carcinoma, areas of intestinal metaplasia in stomachs bearing carcinoma are areas of intestinal metaplasia in stomachs showing atrophic gastritis only were examined for eight markers: a tumour-derived colon-specific antigen (tCSA), carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), pregnancy-specific beta-glycoprotein 1 (SP1), human placental lactogen (HPL), human beta chorionic gonadotrophin (beta-HCG), transferrin (TF) and ferritin (FE). In terms of the number of markers demonstrated in each of the three categories, there is a close similarity between the cells of adenocarcinoma and cells of intestinal metaplasia in cases of cancer, but not to similar metaplastic cells in atrophic gastritis cases. In addition, it appears that the presence of tCSA and SP1 is closely linked to carcinoma, though only approximately half of such cases contain these markers. It would also appear that there are two types of morphologically identical intestinal metaplasia, one related to cancer, the other not. No difference was found between so-called intestinal type and diffuse-type carcinomas.

Clinical studies on the radioimmunodetection of tumors containing alpha-fetoprotein

This study reports the use of radiolabeled antibodies to alpha-fetoprotein for the detection and localization of hepatocellular and germ cell carcinomas. Twelve patients with histories of histologically-confirmed neoplasia received a total dose between 1.0 and 4.4 mCi of 131I-labeled goat IgG prepared against human alpha-fetoprotein. Total-body photoscans were taken with a gamma scintillation camera at various intervals after injection of the radioactive antibody. Computer subtraction of radioactive technetium background images from the antibody 131I scans permitted the visualization of all tumor sites known to be present in 4 patients with either primary hepatocellular cancer or metastatic germ cell carcinoma of the testis. In contrast to the results with the specific antibody, radioactive normal goat IgG given to one of these patients with metastatic embryonal carcinoma of the testis failed to show equivalent localization. Among 8 patients with diverse neoplasms not believed to contain alpha-fetoprotein, 5 of 19 tumor sites showed radioactive antibody accretion, although significantly less than in the patients with liver or testicular cancer. Circulating antigen levels of up to 15,000 ng per milliliter did not prevent successful tumor imaging after intravenous injection of the radioantibody. This investigation indicates that alpha-fetoprotein-containing tumors can be detected and localized in vivo by the method of radioimmunodetection.

Radioimmunodetection of colorectal cancer

This study examines the accuracy of colorectal cancer radioimmunodetection. Twenty-seven patients with a history of histologically-confirmed colonic or rectal carcinoma received a high-titer, purified goat anti-CEA IgG labelled with 131-I at a total dose of at least 1.0 muCi. Various body views were scanned at 24 and 48 hours after administration of the radioantibody. Three additional cases were evaluated; one had a villous adenoma in the rectum and received the 131-I-labelled anti-CEA IgG, while two colonic carcinoma patients received normal goat IgG labelled with 131-I. All of the 7 cases with primary colorectal cancer showed true-positive tumor localization, while 20 of 25 sites of metastatic colorectal cancer detected by immune scintigraphy were corroborated by other detection measures. The sensitivity of the radioimmunodetection of colorectal cancers (primary and metastatic) was found to be 90% (true-positive rate), the putative specificity (true-negative rate) was 94%, and the appraent overall accuracy of the technique was 93%. Neither the case of a villous adenoma receiving the anti-CEA IgG nor the two cases of colonic cancer receiving normal goat IgG showed tumor radiolocalization. Very high circulating CEA titers did not appear to hinder successful tumor radiolocalization. These findings suggest that in colorectal cancers the method of CEA radioimmunodetection may be of value in preoperatively determining the location and extent of disease, in assessing possible recurrence or spread postoperatively, and in localizing the source of CEA production in patients with rising or elevated CEA titers. An ancilliary benefit could be a more tumor-specific detection test for confirming the findings of other, more conventional diagnostic measures.

Immunohistopathologic study on carcinoembryonic antigen (CEA)-like material and immunoglobulin A in gastric malignancies

Immunofluorescent staining for carcinoembryonic antigen (CEA)-like material and immunoglobulin A (IgA) was performed on 54 gastric specimens showing normal mucosa and various lesions including malignancy. Both CEA-like material and IgA were demonstrated in normal mucosa and benign and malignant epithelial lesions. Abnormal findings in respect to CEA-like material included staining of cell membranes with disordered pattern and increased cytoplasmic staining. Several staining characteristics for CEA-like material were shown by various types of malignant epithelial tumors. This staining provides a means of distinguishing anaplastic carcinoma from histiocytic lymphoma, as the latter does not demonstrate CEA-like material. IgA was consistently absent in anaplastic carcinomas, but was noted on the inner surface of tubular components in the differentiated adenocarcinomas, indicating functional preservation in the differentiated tumors. Immunohistochemical staining for CEA-like material and IgA is considered to be useful in the structural and functional study of gastric malignancies.

Purification of human intestinal goblet cell antigen (GOA), its immunohistological demonstration in the intestine and in mucus producing gastrointestinal adenocarcinomas

Goblet cell antigen (GOA) was purified from gastric signet ring cell carcinoma. It was immunogenic and was used to produced antisera which stained goblet cells of the small and large intestine and of intestinalized gastric mucosa by indirect immunological methods. Various types of gastric and colonic cancer contained GOA. These findings demonstrate a histiogenic relationship between intestinal goblet cells, various gastrointestinal cancers and associated premalignant conditions.

Alcian blue staining intestinal goblet cell antigen (GOA): a marker for gastric signet ring cell and colonic colloidal carcinoma

An Alcian blue staining, perchloric acid-soluble, antigenic acidic mucosubstance (GOA) was purified from human gastric signet ring cell carcinoma with DEAE-cellulose chromatography, Seqhadex G-200 and preparative polycrylamide gel electrophoresis. Specific antisera were raised which reacted in indirect immunoenzyme histology with normal goblet cells of the small and large intestine and with goblet cells of intestinalized gastric mucosa. In surgical resection specimens of the stomach (n = 100) and of the colon (n = 19) 3 gastric signet ring cell carcinomas and 3 colonic colloidal adenocarcinomas stained for GOA, demonstrating an immunochemical relationship with normal intestinal goblet cells.

Further characterization of CSAp, an antigen associated with gastrointestinal and ovarian tumors

Colon-specific antigen-p, or CSAp, was originally extracted from GW-39 tumors, which are human colonic carcinomas serially transplanted in golden hamsters, and antibodies to CSAp have been produced in the same animal hosts. By means of immunodiffusion and a hemagglutination-inhibition assay, CSAp has been found to be restricted to adult and fetal small intestine, neoplastic gastric and colonic tissues, inflamed colon, and cystic mucinous tumors of the ovary. CSAp was shown to be distinct from blood group antigens, including Lea and Leb blood group substances, liver ferritin, AFP, CEA, CSA, CMA, ZGM, and BOFA, and to have the electrophoretic mobility of an alpha2-globulin. Gel filtration studies indicated that CSAp in GW-39 tumor, primary human colonic carcinoma, and ovarian cancer mucinous cyst fluid had a peak molecular size range of 70,000--110,000. Quantitation of CSAp in 214 tissue specimens by the hemagglutination-inhibition assay revealed a progressive increase in fetal, inflamed, and neoplastic intestine, such that CSAp in colonic tumors was increased over normal colon tissue. Thus, CSAp appears to be an organ-specific antigen showing increased levels in some gastrointestinal and ovarian neoplasms, as well as in specimens with colitis.

Use of radiolabeled antibodies to carcinoembryonic antigen for the detection and localization of diverse cancers by external photoscanning

To determine whether tumors containing carcinoembryonic antigen could be detected by administration of a radiolabeled, affinity-purified, goat lgG having 70 per cent immunoreactivity against carcinoembryonic antigen, 18 patients with a history of cancer of diverse histopathology received an average total dose of 1.0 mCi of 131l-labeled lgG. Total-body photoscans were performed with a gamma scintillation camera at various intervals after administration of the radioactive antibody. Ordinary photoscans proved difficult to interpret because of blood-pool background radioactivity, thus necessitating the computer subtraction of radioactive blood-pool agents from the antibody's 131l activity. Tumor location could be demonstrated at 48 hours after injection in almost all cases studied. The scans were negative in patients without demonstrable tumors or with tumors apparently devoid of carcinoembryonic antigen. Circulating antigen levels of up to 350 ng per milliliter did not prevent successful tumor imaging after injection of the radioantibody.