Mireille Kremer

Pharmacokinetic study of radiolabeled anti-colorectal carcinoma monoclonal antibodies in tumor-bearing nude mice

Monoclonal antibodies (MoAbs) 17-1A and 19-9, which specifically bind human colorectal carcinoma (CRC) cells, were tested for their usefulness in localizing colorectal tumors in nude mice. One of the 131I-labeled MoAbs and an irrelevant 125I-labeled immunoglobulin of the same isotype were injected into nude mice simultaneously bearing a human CRC and a human melanoma. The percentage of the injected dose of antibody per gram of tissue, the CRC/tissue ratios of antibody distribution, and the localization indices were calculated at various time intervals (2 h to 9 days). For both MoAbs, labeling to a specific activity of 10 μCi/μg by the iodogen method gave optimum immunoreactivity. The accumulation of MoAb 17-1A in CRC reached its maximum at 5 days and remained at this level for up to 9 days postinjection. For MoAb 19-9, which detects a circulating antigen shed by the tumor into the serum, the accumulation in the CRC was maximum at 24 h, and decreased thereafter. The CRC/organ ratios and localization indices for both MoAbs increased with time in the CRC tissue, but remained low and unchanged in the melanoma and normal tissues. Using F(ab′)2 antibody fragments, faster kinetics with earlier maximum accumulation, higher tumor/organ ratios, and better localization indices were achieved than with intact MoAbs. The data obtained was useful in defining parameters which must be considered before radiolabeled MoAbs are used in cancer patients for diagnostic purposes.

Feasibility study of radioimmunoguided surgery of colorectal carcinomas using indium-111 CEA-specific monoclonal antibody

The study was undertaken to define the potential use of indium 111 carcinoembryonic antigen-specific antibody labelled [CEA F(ab′)2] for the radioimmunodetection of colorectal carcinoma using an intraoperative hand-held gamma probe. The use of a linear radioactive source allowed optimization of physical characteristics. The best results regarding sensitivity and resolution were obtained using a 5-mm thick tungsten alloy collimator. A simulation study with a liver phantom (22 MBq or 0.6 mCi) was performed to determine the effect of side scatter as opposed to direct background and showed that it is possible to detect small radioactive targets (3.7 KBq or 0.1 μCi) 4 cm from the phantom. A clinical study performed with ten patients showed that tumours with good uptake of CEA-specific antibody could be detected with sufficient contrast in two patients when the probe was used. Results of a biodistribution study performed after tumour fragment or normal tissue countings in a well counter showed high tumour uptake (above 8 x 10−3 injected dose/g) and tumour-to-normal tissue ratios (between 2.5 and 20) in five patients. Results with the probe showed markedly lower ratios. There was no correlation between absolute tumour uptake and the count rates of tumour measured intraoperatively. This can be attributed to the degradation of depth resolution resulting from the high energy photopeak of gamma-emitting111In.

Enzyme-linked immunosorbent assay to monitor colorectal carcinoma patients treated with a monoclonal antibody (17-1A)

An enzyme-linked immunosorbent assay (ELISA) was compared to a radioimmunoassay (RIA) for the detection and quantification of mouse monoclonal antibody MoAb 17-1A and for measurement of the host response (i.e. anti-mouse immunoglobulin in sera from patients receiving immunotherapy with MoAb 17-1A. Comparable sensitivity and reproducibility were noted with RIA and ELISA but ELISA was more rapid to perform than RIA. Thus quantitative ELISA compared favorably with the RIA for MoAb detection.

Complementary roles of immunoscintigraphy and ultrasonography

A female patient raised the problem of detection of a primary tumor after discovery of multiple nodular, apparently metastatic, lung densifications. Immunoscintigraphy using an anti-CEA antibody revealed two hot spots above and to the right of the urinary bladder. Ultrasonography showed a right ovarian cyst and normal echo texture for the uterus. Surgery confirmed the diagnosis of a right ovarian cyst with a macroscopically normal uterus. Pathological examination demonstrated adenoacanthomatous involvement of the walls of the ovarian cyst and of the uterus. The results of immunoscintigraphy were thus determinant in visualizing the expression of CEA by the ovarian cyst and by the uterus and thus in suggesting their malignancy.

Immunohistocytochemical Analysis of Gastrointestinal Carcinomas Using Immunoperoxidase and Immunogold Staining with Monoclonal Antibodies 19.9 and Anti CEA

Abstract Two monoclonal antibodies anti-CEA and 19.9, have been tested at tissue and cell levels by immunoperoxidase in light microscopy, and immunogood staining in electron microscopy on gastrointestinal adenocarcinomas. With immunoperoxidase assay, 122 primary tumors have been tested: Out of 42 colorectal carcinomas, positivity was 76% with MoAb 19.9, and 90% with MoAb anti-CEA; With other gastrointestinal carcinomas (pancreas, biliary-tract, stomach) positivity was 92% with MoAb 19.9, and 73% with MoAb anti-CEA; for non gastrointestinal adenocarcinomas (breast, parotid, bronchoalveolar, ovary) positivity 32% with MoAb 19.9, and 20% with MoAb anti-CEA; All non glandular tumors (lymphosarcoma, insulinoma, glucagonoma) were negative. Twelve primary tumors and their recurrences were tested, the two monoclonal antibodies appeared to be complementary. With immunogold staining, four colorectal adenocarcinomas have been tested. We observed heterogeneous antigenic display in malignant cells. The labelling was localized punctually, on the cytoplasm, never on the nucleus, just a little on cell membrane. The labelling was localized preferentially at the apical pole of the enterocyte.