Tina Parsons

High expression of Lewis y/b antigens is associated with decreased survival in lymph node negative breast carcinomas.

IntroductionThere is sufficient evidence that blood group related Lewis antigens are tumour-associated molecules. The Lewisy and Lewisb antigens are complex carbohydrates that are over-expressed by breast, lung, colon and ovarian cancers. The SC101 mAb is a unique Lewisy/b binding antibody that binds to native and extended Lewisy and Lewisb haptens, displaying no cross reactivity with H type 1, H type 2, Lewisx or normal blood group antigens.MethodsImmunohistochemical detection of Lewisy/b was performed on 660 formalin-fixed, paraffin embedded breast tumour specimens using a streptavidin-biotin peroxidase technique. Tissue from these patients had previously been included in tissue microarrays. This cohort comprises a well characterized series of patients with primary operable breast cancer diagnosed between 1987 and 1992, obtained from the Nottingham Tenovus Primary Breast Carcinoma Series. This includes patients 70 years of age or less, with a mean follow up of 7 years.ResultsOf the breast carcinomas, 370 of 660 (56%) were negative for Lewisy/b expression, 110 (17%) cases showed a low level of expression (<25% of positive cells) and only 54 cases (8%) showed extensive expression of Lewisy/b (>75% of positive cells). We found significant positive associations between histological grade (p < 0.001), Nottingham Prognostic Index (p = 0.016), tumour type (p = 0.007) and the level of Lewis y/b expression. There was a significant correlation between the proportion of Lewisy/b positive tumour cells and survival in lymph-node negative patients (p = 0.006).ConclusionThe unique epitope recognised by SC101 mAb on Lewisy/b hapten is over-expressed on breast tumour tissue compared with normal breast. In this large series of invasive breast cancers, higher expression of Lewisy/b was more often found in high grade and poor prognosis tumours compared to good prognosis cancers. Moreover, in lymph node negative breast carcinomas, over-expression of Lewisy/b hapten was associated with significantly decreased patient survival.

A New Anticancer Glycolipid Monoclonal Antibody, SC104, which Directly Induces Tumor Cell Apoptosis

A novel monoclonal antibody was raised by immunization of mice with colorectal tumor cell lines. The fusion was screened by immunohistochemistry for binding to primary colorectal tumors. Subsequent analysis on primary disaggregated colorectal tumors show that the antibody recognizes a cell surface antigen expressed by the majority of colorectal tumors. Antigen characterization has shown that the antibody recognizes a sialyltetraosylceramide but does not bind to GM1, GD1a, GT1b, or sialyl Lewis(X) antigens. Binding to a frozen panel of tumor and normal tissue sections revealed that the antigen was also strongly expressed on esophageal, gastric, and endometrial tumors. Its normal tissue distribution was largely restricted to moderate staining of large intestine. Surprisingly, SC104 antibody directly induces tumor cell death without the need for immune effector cells or complement. This may be related in part to its homophilic binding properties that allow cross-linking of antibody and receptors on the cell surface. Caspase activation can be detected following SC104 treatment of colorectal cells, and cotreatment with caspase inhibitors has been shown to inhibit cell death. This suggests that SC104 induces death by a classic apoptotic pathway. Furthermore, SC104 antibody shows additive killing with complement and 5-fluorouracil/leucovorin in vivo, suggesting a new therapeutic approach for this class of antibodies.

Human anti-idiotypic antibodies can be good immunogens as they target FC receptors on antigen-presenting cells allowing efficient stimulation of both helper and cytotoxic T-cell responses

Anti‐idiotypic antibodies that mimic tumour‐associated antigens can stimulate anti‐tumour T‐cell responses. In this article, we have studied the role of Fc in the presentation of T‐cell epitopes by 2 anti‐idiotypic antibodies, 105AD7 and 708. The human monoclonal antibody 105AD7, which mimics CD55, stimulated strong in vitro T‐cell proliferation, γIFN secretion and redirected cytotoxicity in unprimed T cells from healthy donors. However, removal of the Fc region of the anti‐idiotype reduced the sensitivity of the assay 1,000‐fold, as did inhibiting Fc uptake of the anti‐idiotype by an excess of human IgG. The mouse anti‐idiotype 708, which mimics CEA, failed to stimulate in vitro T‐cell responses on unprimed T cells from healthy donors. However, when a human IgG1 Fc region replaced its mouse Fc region, the anti‐idiotype induced T‐cell proliferation, γIFN secretion and redirected cytotoxicity in lymphocytes from unimmunised donors. Human anti‐idiotypes are therefore good immunogens since they target Fc receptors on antigen‐presenting cells, allowing efficient stimulation of both helper and cytotoxic T‐cell responses. The immunogenicity of other anti‐idiotypes may therefore be enhanced by human Fc targeting of antigen‐presenting cells.

Therapeutic Targeting of Lewisy and Lewisb with a Novel Monoclonal Antibody 692/29

Background Several monoclonal antibodies (mAbs) recognising Lewisy, such as BR96, have reached the clinic but have failed to show good anti-tumour responses with an acceptable level of toxicity. No Lewisb mAbs have been trialled in patients. In this study we compare the specificity of three mAbs; BR96 (Lewisy), 2-25 LE (Lewisb) and 692/29 that recognises a unique facet of both Lewisy and Lewisb. We then assessed the in vivo therapeutic effect of 692/29 using xenograft models. Methodology/Principal Findings Using a glycan array, each mAb was shown to display a different binding pattern with only 692/29 binding to both Lewisy and Lewisb. 692/29 was able to kill tumour cells over-expressing Lewisy/b directly, as well as by antibody and complement mediated cytotoxicity (ADCC/CDC), but failed to kill cells expressing low levels of these haptens. In contrast, BR96, directly killed cells expressing either high or low levels of Lewisy perhaps explaining its toxicity in patients. 2-25 LE failed to cause any direct killing but did mediate ADCC/CDC. Both 692/29 and BR96 bound to >80% of a panel of over 400 colorectal tumours whereas 2-25 LE showed lower reactivity (52%). 692/29 demonstrated more restricted normal tissue reactivity than both BR96 and 2-25 LE. 692/29 anti-Lewisy/b mAb also showed good in vivo killing in xenograft models. Conclusions/Significance MAbs targeting both Lewisy and Lewisb may have a therapeutic advantage over mAbs targeting just one hapten. 692/29 has a more restricted normal tissue distribution and a higher antigen threshold for killing which should reduce its toxicity compared to a Lewisy specific mAb. 692/29 has an ability to directly kill tumours whereas the anti-Lewisb mAb does not. This suggests that Lewisy but not Lewisb are functional glycans. 692/29 showed good anti-tumour responses in vivo and is a strong therapeutic candidate.

Monoclonal Antibodies Targeting LecLex-Related Glycans with Potent Antitumor Activity

Purpose: To produce antitumor monoclonal antibodies (mAbs) targeting glycans as they are aberrantly expressed in tumors and are coaccessory molecules for key survival pathways. Experimental Design: Two mAbs (FG88.2 and FG88.7) recognizing novel tumor-associated Lewis (Le) glycans were produced by immunizations with plasma membrane lipid extracts of the COLO205 cell line. Results: Glycan array analysis showed that both mAbs bound LecLex, di-Lea, and LeaLex, as well as Lea-containing glycans. These glycans are expressed on both lipids and proteins. Both mAbs showed strong tumor reactivity, binding to 71% (147 of 208) of colorectal, 81% (155 of 192) of pancreatic, 54% (52 of 96) of gastric, 23% (62 of 274) of non–small cell lung, and 31% (66 of 217) of ovarian tumor tissue in combination with a restricted normal tissue distribution. In colorectal cancer, high FG88 glyco-epitope expression was significantly associated with poor survival. The mAbs demonstrated excellent antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), in addition to direct tumor cell killing via a caspase-independent mechanism. Scanning electron microscopy revealed antibody-induced pore formation. In addition, the mAbs internalized, colocalized with lysosomes, and delivered saporin that killed cells with subnanomolar potency. In vivo, the mAbs demonstrated potent antitumor efficacy in a metastatic colorectal tumor model, leading to significant long-term survival. Conclusions: The mAbs direct and immune-assisted tumor cell killing, pan-tumor reactivity, and potent in vivo antitumor efficacy indicate their potential as therapeutic agents for the treatment of multiple solid tumors. In addition, internalization of saporin conjugates and associated tumor cell killing suggests their potential as antibody drug carriers. Clin Cancer Res; 21(13); 2963–74. ©2015 AACR.