S. Carrel

Tumor localization of radiolabeled antibodies against carcinoembryonic antigen in patients with carcinoma: a critical evaluation.

Purified, [131I]-labeled goat antibodies against carcinoembryonic antigen, which have been shown to localize in human carcinoma in nude mice, were injected into 27 patients with carcinoma. Patients were scanned with a scintillation camera at various intervals. In 11 patients, radioactivity was detectable in the tumor 48 hours after injection. Computerized subtraction of blood-pool radioactivity provided clearer pictures in positive cases, but in 16 patients the scans remained doubtful or negative. To study the specificity of [131I]-antibody localization, we gave some patients simultaneous injections of [125I]-labeled normal IgG. Both isotopes were measured by means of scintillation counting in tumors and normal tissues recovered after surgery. The results demonstrated that only the anti-CEA antibodies localized in tumors. However, the total antibody-derived radioactivity in the tumor was only about 0.001 of the injected dose. We conclude that, despite the present demonstration of specificity, this method of tumor detection is not yet clinically useful.

Expression of neuroectodermal antigens common to melanomas, gliomas, and neuroblastomas

SummaryThe reactivity spectrum of five different monoclonal anti-melanoma antibodies cross-reacting with gliomas and neuroblastomas and one monoclonal anti-glioma antibody cross-reacting with melanomas and neuroblastomas was investigated. Comparison of the binding activity of these monoclonal antibodies for 11 melanoma, seven glioma, and three neuroblastoma cell lines showed that each of these clones had a different pattern of cross-reactivity. The results indicated that the antigenic determinants detected by these antibodies were not associated with the same antigen and thus suggested the existence of at least six different antigens common to melanomas, gliomas, and neuroblastomas. Since all these tumors are known to derive from cells originating embryologically from the neural crest, it can be assumed that the antigens recognized by our monoclonal antibodies are neuroectodermal differentiation antigens.However, absorption with fetal brain homogenates abolished only the binding of monoclonal anti-glioma antibody, but did not modify the binding of monoclonal anti-melanoma antibodies.

Monoclonal antibodies against carcinoembryonic antigen (CEA) used in a solid-phase enzyme immunoassay. First clinical results.

A solid-phase enzyme immunoassay using both mouse monoclonal and goat polyclonal antibodies against carcinoembryonic antigen (CEA) was developed. The assay detects 0.6 to 1.2 ng of CEA per ml of serum and has 3 incubation steps which can be performed in 1 day. Polystyrene balls coated with polyclonal goat anti-CEA antibodies are first incubated with heat-extracted serum samples. Bound CEA is then detected by addition of mouse monoclonal antibodies, followed by goat IgG anti-mouse IgG1 coupled to alkaline phosphatase. Results with this enzyme immunoassay using monoclonal antibodies (M-EIA) have been compared with those obtained by the conventional inhibition radioimmunoassay (RIA) using goat antiserum. Three hundred and eighty serum samples from 167 patients with malignant or non-malignant diseases and from 134 normal individuals with or without heavy smoking habits were analyzed by the 2 assays. Excellent correlation between the results of the 2 assays was obtained, but the M-EIA, using monoclonal antibodies from a single hybridoma, did not discriminate better than the conventional RIA between CEA produced by different types of carcinoma and between CEA associated with malignant or non-malignant diseases. Follow-up studies of several patients by sequential CEA determinations with the 2 assays showed that the M-EIA was as accurate as the RIA for the detection of tumor recurrences.

Sandwich enzyme immunoassay using three monoclonal antibodies against different epitopes of carcinoembryonic antigen (CEA)

Purified monoclonal antibodies (Mab) produced by 3 hybridomas and reacting with 3 different epitopes of carcinoembryonic antigen (CEA) were used in a solid phase enzyme immunoassay. Two Mabs were physically adsorbed to polystyrene balls and the third Mab was coupled to alkaline phosphatase using the bifunctional reagent N-succinimidyl-3-(2-pyridyldithio)-propionate. During a first incubation, CEA from heat-extracted serum samples was immunoadsorbed to the antibody coated balls. After washing of the balls, bound CEA was detected by a second incubation with the enzyme coupled Mab. The sensitivity of the assay was 0.6 ng per ml of serum. A total of 196 serum samples from patients with various types of carcinoma, with liver cirrhosis, or from healthy blood donors with or without smoking habits, were tested. The results obtained with the monoclonal enzyme immunoassay (M-EIA) were compared with those obtained with perchloric acid extracts of the same serum samples tested by an inhibition radioimmunoassay using conventional goat anti-CEA antiserum. There was an excellent correlation between the two assays. In particular, the new M-EIA gave good results for the detection of tumor recurrences in the follow-up of colon carcinoma patients. However, despite the use of exclusively monoclonal antibodies the new assay detected a similar percentage of slightly elevated CEA values as the conventional assay in patients with non-malignant disease, suggesting that the CEA associated with non-malignant diseases is immunologically identical to the CEA released by colon carcinoma.

Use of Monoclonal Antibodies for the Histological Localization of Melanoma Associated Antigens on Fresh Tumor Material

Abstract For the staining of fresh tumor tissue with monoclonal antibodies, a three-stage biotin-avidin-peroxidase system was used. All tumor specimens were frozen within 15 min after excision and stored at −80° C until use. A series of primary and metastatic melanoma have been analyzed using 7 monoclonal anti-melanoma antibodies and 3 anti-glioma antibodies crossreacting with melanomas. Several other monoclonal antibodies, generated in our laboratory, were included in each experiment such as an anti-HLA-DR, an anti-T, an anti-CALLA and an anti-CEA. The results obtained showed a distinct staining pattern of the tumor masses with each monoclonal anti-melanoma tested. Almost no staining of the surrounding normal tissue was observed. The monoclonal anti-CALLA antibody displayed a faint staining of some of tumor nodules. With the monoclonal anti-HLA-DR antibody a positive staining of both the tumor cells and the infiltrating inflammatory cells was observed. The anti-T antibody stained the lymphoid cells infiltrating some of the tumors.

Tumor Localization of Radio-Labeled Antibodies against Carcinoembryonic Antigen in Patients with Carcinoma

Purified, [131I]-labeled goat antibodies against carcinoembryonic antigen, which have been shown to localize in human carcinoma in nude mice, were injected into 27 patients with carcinoma. Patients were scanned with a scintillation camera at various intervals. In 11 patients, radioactivity was detectable in the tumor 48 hours after injection. Computerized subtraction of blood-pool radioactivity provided clearer pictures in positive cases, but in 16 patients the scans remained doubtful or negative. To study the specificity of [131I]-antibody localization, we gave some patients simultaneous injections of [125I]-labeled normal IgG. Both isotopes were measured by means of scintillation counting in tumors and normal tissues recovered after surgery. The results demonstrated that only the anti-CEA antibodies localized in tumors. However, the total antibody-derived radioactivity in the tumor was only about 0.001 of the injected dose. We conclude that, despite the present demonstration of specificity, this method of tumor detection is not yet clinically useful.

Monoclonal Antibody SRB5B1 Recognizes a Ganglioside Antigen Shared by Human Melanoma and Colon Carcinoma Cell Lines

Abstract This paper describes the obtention of an IgG2a monoclonal antibody which recognizes an antigen preferentially expressed on human melanoma as well as colon carcinoma cell lines and undetectable on normal diploid cell lines. Emphasis is made on the quantitative expression of this antigen on a panel of various tumor cell lines: whereas 70 % of melanomas and colon carcinomas bind a high amount of antibody molecules per cell (10 4 to 10 6 ), tumors from other origins including brain tumors, generally bind lower (10 3 to 10 4 MAb molecules/cell) or undetectable ( 3 MAb molecules/cell) amounts. A low binding level ( 4 molecules/cell) is also revealed by flow cytometry analysis on some monocytes and granulocytes from normal blood and bone-marrow. The impossibility to immunoprecipitate the corresponding antigen, its resistance to heat-treatment and its sensitivity to neuraminidase treatment suggest that it might be a ganglioside.

Radiolabeled Antibodies for the Detection of Cancer: New Approaches to Improve the Sensitivity and Specificity of Immunoscintigraphy

Paul Ehrlich’s concept of “magic bullet” for the cure of diseases has been revitalized by the development of the monoclonal antibody (Mab) technology allowing the production in unlimited amounts of antibodies of perfect homogeneity and specificity directed against various tumor markers. This chapter will review one aspect of the magic bullet concept, the use of radiolabeled antibodies as tracer for tumor detection by immunoscintigraphy. We shall critically consider the results obtained in this attractive field, from our early experimental results with 131I labeled polyclonal antibodies against carcinoembryonic antigen (CEA) up to the most recent clinical results obtained with 123I labeled fragments of anti-CEA Mab. Special emphasis will be given to the difficulties encountered in the detection of liver metastases when using intact anti-CEA antibodies and to the improvement obtained when we used 123I labeled Mab fragments and single photon emisssion computerized tomography (SPECT) for their localization in three dimensions.