Immunostaining of colorectal cancer with monoclonal anti-CEA antibodies compared to serum and tumor CEA content

Carcinoembryonic antigen was measured in serum and in extracts from 37 colorectal tumors and we found a poor correlation between circulating and tumor CEA. Monoclonal antiCEA antibodies were used in indirect immunoperoxidase staining of the corresponding formalin fixed tissue sections. We found that serum CEA measurement had a sensitivity of only 41.9% as compared to 90.3% for the immunohistochemical staining. The positive and negative predictive values for immunostaining were respectively 96.6% and 72.7%. Immunohistochemical staining of tissue sections with monoclonal anti CEA coupled to other biochemical or immunological assays could be a useful adjunct for the diagnosis of premalignant or slightly modified tissues.     

Comparison of anti-fetal colonic microvillus and anti-CEA antibodies in peroperative radioimmunolocalisation of colorectal cancer

Local recurrence of colorectal cancer may result from failure to assess accurately the extent of tumour at operation. It has been suggested that peroperative radioimmunolocalisation may improve this assessment. The degree to which this is possible has been studied using a hand-held gamma detecting probe and comparing two 125I-labelled monoclonal antibodies to colorectal tumours. The antibodies were to fetal colonic microvillus membrane (FM1D10) and to carcinoembryonic antigen (A5B7). Sixty-nine per cent (9/13) of the FM1D10 and 98% (43/44) of A5B7 labelled tumours took up significant amounts of antibody with a tumour to normal colon ratio of more than 1.5:1. The uptake was significantly better for A5B7 with a median tumour to normal colon ratio of 3.3 (1.1-13.8) compared to 1.85 (0.75-7.7) for FM1D10 (P less than 0.001). The tumour: colon ratio of both antibodies was independent of the serum CEA, Dukes' stage or the degree of histological differentiation. There was a linear correlation for tumour to normal colon ratios between the gamma detecting probe and the same tissue examined in a conventional well counter (correlation coefficient r = 0.78, P less than 0.001). Colorectal tumours demonstrate a rapid and reliable uptake of anti-CEA monoclonal antibody A5B7. This antibody can be detected with a peroperative gamma detecting probe and has the potential to improve the surgeon's appreciation of the extent of tumour and therefore may influence the surgery performed. Detailed clinical studies are now being carried out.     

Diagnosis and treatment of colorectal cancer using monoclonal antibodies

The clinical usefulness of monoclonal antibodies was discussed from the viewpoint of serodiagnosis, immunohistochemistry, radio immunodetection and therapy. Monoclonal antibodies against carcinoembryonic antigen (CEA) were shown to be more beneficial than polyclonal antibodies. Carbohydrate antigens such as CA 19-9 or CA 50 were also available as tumor markers of colorectal cancer to a certain extent.     

The diagnostic and therapeutic use of monoclonal antibodies in colorectal cancer

Preliminary trials have illustrated that monoclonal antibodies can be administered safely, tumor binding can be achieved, and sensitive radioimaging may be possible. Additionally, clinical responses in patients with colorectal carcinoma can occur. The limitations of murine monoclonal therapy are now being addressed and in time will be overcome. Monoclonal antibodies offer great promise in the diagnosis and therapy of malignant disease. Further investigation using innovative approaches and in combination with other therapies may help to reach this goal.     

Complementation of anti-CEA and anti-TAG-72 monoclonal antibodies in reactivity to human gastric adenocarcinomas

Monoclonal antibody (MAb) B72.3 and MAb COL-4 are reactive with the high-molecular-weight (Mr greater than 10(6] tumor-associated glycoprotein (TAG)-72, and the Mr 180,000 carcino-embryonic antigen (CEA), respectively. Antibody competition radioimmunoassays (RIAs) using 125I-MAb B72.3 or 125I-COL-4 have demonstrated that each MAb also recognizes a distinct antigenic determinant. Solid-phase RIAs using MAbs B72.3 and COL-4, however, demonstrated similar reactivity for each MAb with gastric carcinomas versus normal gastric mucosa. Tissue sections from all of 17 gastric adenocarcinomas also reacted with both MAb B72.3 and MAb COL-4 when immunoperoxidase techniques were used. Double-staining techniques using both MAbs on the same section were performed on formalin-fixed, paraffin-embedded gastric tissue sections using the combination of avidin-biotin peroxidase complex and avidin-biotin alkaline phosphatase complex immunohistochemical methods. The double-staining technique revealed that some carcinoma cells react with MAb B72.3, some react with MAb COL-4, and others react with both MAbs. This technique has demonstrated that more carcinoma cells can be detected by both MAbs as compared to the number of stomach carcinoma cells shown to be reactive with either one or the other MAb. These studies thus define the rationale for the use of combinations of MAbs which recognize different tumor-associated antigens as immunological adjuncts for detection and perhaps therapy of gastric carcinoma.     

Detection of carcinoembryonic antigen in colonic effluent by specific anti-CEA monoclonal antibodies.

To characterize the CEA in colonic effluent, anti-CEA monoclonal antibody COL-4 was used in a qualitative radioimmunoassay in both fractionated and unfractionated colonic effluent. Both effluent samples and tissue extracts, were subjected to Western blotting and tissue sections to immunohistochemistry. Quantitative levels of colonic effluent CEA were determined by a kit (Abbott-EIA). Higher mean values of COL-4 binding activity were seen only in patients with a past history of polyps (P < 0.01). Quantitated CEA correlated with the presence of colorectal cancer (CRC) as compared to normal subjects, (1133 +/- 875 vs. 459 ng/ml +/- 602, P < 0.05) but not when standardized for protein content. COL-4 reacted with an 180,000 M(r) CEA in the effluent and activity was associated with membrane fraction of the effluent, but bore no relation to the immunohistological staining. We conclude that CEA is detectable in colonic effluent and is membrane associated, but the overlapping values in effluent samples do not make this a useful test in the diagnosis of CRC.     

Circulating anti-CEA antibodies in the sera of patientswith breast cancer

AIM: The aim of this study was to detect circulating anti-carcinoembryonic antigen antibodies (anti-CEA) in breast cancer patients and to evaluate their clinical and prognostic significance. METHODS: Fifty-two breast cancer patients and 28 controls were included in this study. Detection of anti-CEA antibodies was performed using a modified enzyme linked immunoassay (ELISA). Sensitivity, specificity and usefulness index of anti-CEA antibodies were compared to those of CEA. The correlation of anti-CEA antibodies with survival and recurrence-free survival was tested with univariate and multivariate analysis. RESULTS: Anti-CEA was present in 57% of breast cancer patients and in 11% of controls. The sensitivity and usefulness index of anti-CEA were significantly better than those of CEA. The specificity of anti-CEA antibodies was less than that of CEA, the difference not being statistically significant. Anti-CEA antibodies were an independent statistically significant, favourable factor in recurrence-free survival. CONCLUSION: Anti-CEA antibodies circulate in breast cancer patients. They could be used as a more sensitive tumour marker than CEA. Their presence is associated with improved recurrence-free survival. These results should be confirmed in a larger series.     

EGFR单克隆抗体治疗转移性结直肠癌的耐药分子机制

靶向表皮生长因子受体（EGFR）的单克隆抗体是转移性结直肠癌（mCRC）的重要治疗药物,但有效率并不理想,主要原因是存在严重的原发性和继发性耐药。本文从分子改变的方面就靶向EGFR单克隆抗体（anti EGFR mAb）治疗mCRC的耐药分子机制作一综述,旨在为进一步研究anti EGFR mAb耐药机制提供参考,为mCRC患者实现临床个体化治疗提供理论依据。     

Where to position monoclonal antibodies in first-line treatment of advanced colorectal cancer

The treatment of metastatic colorectal cancer with modern cytotoxic agents in combination with monoclonal antibodies against vascular endothelial growth factor (VEGF) and the epidermal growth factor receptor (EGFR) has improved median overall survival from 6 months to almost 2 years. Uncertainty remains over the optimal chemotherapy combination and sequencing, and to which line of treatment monoclonal antibodies should be added. This article reviews the rationale and evidence for the use of monoclonal antibodies in the first-line treatment of metastatic colorectal cancer in both general and specific situations, and provides a perspective on how to position their use in contemporary practice.     

A systematic review of cost-effectiveness of monoclonal antibodies for metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) imposes a substantial health burden on patients and society. In recent years, advances in the treatment of mCRC have mainly resulted from the introduction of monoclonal antibodies (MoAbs). However, the application of these MoAbs considerably increases treatment costs. The objective of this article is to review and assess the economic evidence of MoAB treatment in mCRC. A systematic literature review was conducted and cost-effectiveness (CE) as well as cost-utility-studies were identified. For this, Medline, Embase, SciSearch, Cochrane, and nine other databases were searched from 2000 through February 2013 for full-text publications. The quality of the studies was assessed via a validated assessment tool (Quality of Health Economic Studies (QHES)). A total of 843 publications were screened. Of those, 15 studies involving the MoAbs bevacizumab, cetuximab and panitumumab met all inclusion criteria. Four studies analysed the CE of first-line treatment with bevacizumab and nine the CE of cetuximab in subsequent treatment lines. Two studies dealt with the CE of panitumumab. The analysis of sequential regimes and the direct comparison of two MoABs were analysed by only one study each. The quality of the included studies was high with the exception of one study.ConclusionsThe treatment with bevacizumab, cetuximab and panitumumab is mainly considered to be not cost-effective in patients with mCRC. However, testing for Kirsten ras oncogene (KRAS) mutation prior to the treatment with cetuximab or panitumumab is found to be clearly cost-effective compared to no testing. Future research should focus on the CE of first-line treatment with cetuximab or panitumumab and studies on upcoming agents like regorafenib and aflibercept.     

First-line use of anti-epidermal growth factor receptor monoclonal antibodies in metastatic colorectal cancer

Several molecular pathways have been shown to play key roles in the development and progression of colorectal cancer (CRC). This enhanced understanding of tumor biology has provided the rationale for the design and development of novel agents that are directed against important targets, including growth factors, receptors, and tumor-specific/tumor-selective antigens. The epidermal growth factor receptor (EGFR) signaling pathway has received much attention over the past 5-10 years because it is overexpressed in more than 85% of tumors from patients with metastatic CRC. Cetuximab and panitumumab are monoclonal antibodies presently approved for use by the FDA in the refractory disease setting, and they have provided significant advances in the treatment of advanced CRC. However, much focus has shifted toward using these biologic therapies in combination with cytotoxic chemotherapy in up-front settings, such as first-line therapy and in the neoadjuvant therapy of liver-limited disease. The clinical studies conducted to date suggest that cetuximab can be safely and effectively combined with oxaliplatin- and irinotecan-based chemotherapy in the first-line treatment of metastatic CRC. Moreover, the results of the CRYSTAL phase III study provide support for the use of the combination of FOLFIRI (5-fluorouracil/leucovorin/irinotecan) and cetuximab in the neoadjuvant setting and allow for R0 surgical resection with curative intent. Much work continues to investigate the critical molecular biomarkers that can be used to predict clinical response to chemotherapy and/or targeted therapies as well as to identify which patients might be at increased risk for developing drug-specific side effects.     

Binding of five monoclonal anti-CEA antibodies with different epitope specificities to various carcinoma tissues

Five monoclonal antibodies that recognize different epitopes on carcinoembryonic antigen (CEA) were reacted with tissue sections of various carcinoma specimens. The vital, non-necrotic tissues of those carcinomas of the oesophagus, pancreas, colon and rectum, medullary thyroid, ovary and cervix in which CEA related epitopes were detectable bound all five antibodies to a similar degree. In 3/5 lung carcinomas, 2/10 mammary carcinomas and 1/5 gastric carcinomas, a significantly different binding of the monoclonal antibodies by vital tumour tissue was present as determined by three independent investigators. In necrotic tissue areas, heterogeneity of antibody binding was more common. In a previous investigation, it was shown that normal granulocytes and liver tissue differentially bind the monoclonal anti-CEA antibodies, indicating the presence of crossreacting antigens. The equivalent binding of the five monoclonal anti-CEA antibodies to most of the carcinomas tested suggests that this binding is due to the presence of complete CEA molecules and not only of cross-reacting antigens.     

Clinical use of monoclonal antibodies to the epidermal growth factor receptor in colorectal cancer

Monoclonal antibodies to the epidermal growth factor receptor (EGFR) are among the promising novel targeted therapies being explored in colorectal cancer. Two such agents that inhibit EGFR signaling by interfering with ligand-binding are cetuximab (Erbitux) and panitumumab (Vectibix). This review will address the use of cetuximab and panitumumab in chemotherapy-refractory colorectal cancer as well as in front-line therapy for the disease, consider predictors of response and resistance, and outline comparisons between these agents.     

Immunoscintigraphy of colorectal carcinoma with F (ab')2 fragments of anti-CEA monoclonal antibody

A monoclonal antibody to carcinoembryonic antigen (CEA) (F023C5), belonging to IgG1 class, was obtained by cell fusion technique. Preliminary screening on different tissues was performed with immunoperoxidase staining, which showed good specificity of the antibody for gastric and colorectal carcinomas. F(ab')2 fragments were subsequently prepared and labeled with 131I and 111In. After immunoreactivity check the radiopharmaceuticals were injected intravenously. Sixteen patients with 22 primary or secondary localizations of colorectal carcinoma were studied following the recommendations of the ethical Committee of the Istituto Nazionale Tumori, Milan, Italy. Serial scans were performed after injection of the two radioactive reagents. In vivo pharmacokinetics of the compound was studied. Radioactivity level in surgical specimens was measured, and immunostaining was performed. All tumors were found to express the antigen. Eleven out of 12 tumor localizations of the gastrointestinal tract and three out of ten liver metastases were imaged. Specificity of tumor uptake was assessed by simultaneous injection of an irrelevant antibody.     

Radioimmunotherapy of human colon carcinoma by 131I-labelled monoclonal anti-CEA antibodies in a nude mouse model

A mixture of 3 MAbs directed against 3 different CEA epitopes was radiolabelled with 131I and used for the treatment of a human colon carcinoma transplanted s.c. into nude mice. Intact MAbs and F(ab')2 fragments were mixed because it had been shown by autoradiography that these 2 antibody forms can penetrate into different areas of the tumor nodule. Ten days after transplantation of colon tumor T380 a single dose of 600 microCi of 131I MAbs was injected i.v. The tumor grafts were well established (as evidenced by exponential growth in untreated mice) and their size continued to increase up to 6 days after radiolabelled antibody injection. Tumor shrinking was then observed lasting for 4-12 weeks. In a control group injected with 600 microCi of 131I coupled to irrelevant monoclonal IgG, tumor growth was delayed, but no regression was observed. Tumors of mice injected with the corresponding amount of unlabelled antibodies grew like those of untreated mice. Based on measurements of the effective whole-body half-life of injected 131I, the mean radiation dose received by the animals was calculated to be 382 rads for the antibody group and 478 rads for the normal IgG controls. The genetically immunodeficient animals exhibited no increase in mortality, and only limited bone-marrow toxicity was observed. Direct measurement of radioactivity in mice dissected 1, 3 and 7 days after 131I-MAb injection showed that 25, 7.2 and 2.2% of injected dose were recovered per gram of tumor, the mean radiation dose delivered to the tumor being thus more than 5,000 rads. These experiments show that therapeutic doses of radioactivity can be selectively directed to human colon carcinoma by i.v. injection of 131I-labelled anti-CEA MAbs.     

抗EGFR单抗在转移性结直肠癌中耐药机制的研究进展

抗表皮生长因子受体（EGFR）单克隆单抗分子靶向药物在转移性结直肠癌中的应用,显著改善了患者无进展生存期及总生存期,由于迅速产生继发性耐药限制了其临床运用效果。因此,寻找生物标志物初步筛选敏感人群及预测耐药,以及研究分子靶向药物耐药机制的产生以逆转耐药,都是进一步提高转移性结直肠癌治疗效果的关键,目前靶向药物联合应用有望进一步提高治疗有效率并逆转耐药。