ganglioside--gd2 and Colonic-Neoplasms

In this study, we compare various methods for the detection of a tumor-associated target antigen and deposition of the bound therapeutic monoclonal antibody in patients enrolled in two separate trials, one involving the administration of two radiolabeled monoclonal antibodies and the other involving an unlabeled antibody. In the first trial, patients with TAG-72 expressing metastatic colon cancer scheduled for surgical intervention received radiolabeled murine and chimeric B72.3 antibody followed by radioimmune imaging and subsequent laparotomy. Normal and tumor tissues obtained at surgery were processed for routine histology, immunohistochemistry, radiometry, and autoradiography. Both anti-TAG-72 antibodies localized to known tumor sites as evidenced by radioimmune imaging. Resected tissue revealed a high tumor-to-normal radiolocalization ratio, and autoradiography demonstrated even deposition of the radiolabeled antibodies throughout the entire tumor deposit with sparing of surrounding normal tissue. In contrast, immunohistochemistry on the same sections revealed comparatively weak antigen expression and patchy antibody localization. In the second trial, patients with GD2 antigen expressing metastatic melanoma received the unlabeled chimeric anti-GD2 antibody C14.18. Immunologic detection of the GD2 antigen and C14.18 deposition was performed on biopsy section as well as on single cell suspension. FACS analysis of the single cell suspension proved more sensitive for the detection of bound antibody than immunohistochemistry, although both methods yielded comparable results for GD2 antigen expression. Our findings demonstrate that the optimal method for the detection of tumor-associated antigen and bound therapeutic antibody can vary depending upon the nature of the antibody (radiolabeled vs. unlabeled and murine vs. chimeric), fixation stability of the target antigen, and the type of pathologic material available for study.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Neoplasm; Antibody Specificity; Antigens, Neoplasm; Autoradiography; Clinical Trials as Topic; Colonic Neoplasms; Evaluation Studies as Topic; Flow Cytometry; Fluorescent Antibody Technique, Indirect; Gangliosides; Glycoproteins; Humans; Melanoma; Mice

The antiganglioside GD2 monoclonal antibody 14G2a (Ab1) served as an immunogen to generate the anti-idiotype (anti-Id) 1A7 (IgG1,kappa), which mimics GD2 both antigenically and biologically. Anti-Id 1A7 induced anti-GD2 antibodies in mice and rabbits. In this preclinical study, a pair of cynomolgus monkeys, immunized with 1A7 that had been mixed with QS-21 adjuvant, produced anti-anti-Id antibodies (Ab3), which reacted with the GD2-positive melanoma cell line M21/P6 cells but not with GD2-negative LS174-T cells. The Ab3 shared Ids with mAb 14G2a (Ab1), as demonstrated by their ability to inhibit binding of 1A7 to this Ab1. The Ab3 bound specifically to purified GD2 antigen and competed with the Ab1 14G2a in binding to a GD2-positive melanoma cell line or to purified GD2, suggesting that Ab1 and Ab3 may bind to the same epitope and may behave as an Ab1-like antibody (Ab1'). The isotype of the GD2-specific antibodies was mostly IgG in nature. The specificity of the antibodies for GD2 was further confirmed by dot blot analysis. These antisera also specifically lysed GD2-positive target cells in an antibody-dependent cellular cytotoxicity assay. The induction of anti-GD2 responses in monkeys did not cause any apparent side effects, despite the fact that GD2 antigen is expressed by many normal tissues of these animals. Taken together, these results suggest that anti-Id 1A7 can induce GD2-specific antibodies in nonhuman primates and can thus serve as a potential network antigen for triggering active anti-GD2 antibodies in patients with GD2-positive neuroectodermal tumors.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Anti-Idiotypic; Antibodies, Monoclonal; Antibody Formation; Antibody-Dependent Cell Cytotoxicity; Colonic Neoplasms; Gangliosides; Humans; Macaca fascicularis; Melanoma; Mice; Mice, Inbred BALB C; Rabbits; Tumor Cells, Cultured

Human tumor cells expressing ganglioside GD2 were lysed by various effector populations targeted with an anti-CD3-anti-GD2 bi-specific antibody (BAb CD3 x GD2). This antibody-heteroconjugate was prepared by chemically cross-linking the OKT-3 monoclonal antibody (MAb) reactive with CD3 antigen on T lymphocytes with the ganglioside MAb ME 361, which binds preferentially to the tumor-associated ganglioside GD2. The specificity of target-cell lysis by the cytotoxic T cells (CTL) was mediated by the specificity of the targeting antibody: GD2-negative cells were not lysed in the presence of the CD3 x GD2 BAb. A dose-dependent response was observed in a range of 10 to 10,000 ng/ml. In contrast, 2 other BAbs recognizing the tumor-associated antigens EGF-R and TKB-2 had greater potency to mediate tumor-cell lysis than the GD2 x CD3 BAb. Peripheral-blood cells (PBL) stimulated with OKT-3 MAb or with irradiated tumor cells in a mixed lymphocyte culture (MLTC) could be induced to lyse GD2-positive tumor cells in the presence of CD3 x GD2 BAb. The tumor-cell lysis could be mediated by autologous or allogeneic effector cells. NK cells had no influence on the BAb-induced cytotoxicity.

Topics: Antibodies; Antibody Specificity; CD3 Complex; Colonic Neoplasms; Cross Reactions; Gangliosides; Humans; Immunoglobulin G; Immunotherapy; Killer Cells, Natural; Melanoma; Neoplasms; T-Lymphocytes, Cytotoxic; Tumor Cells, Cultured