Immunohistochemical expression of vascular endothelial growth factor and microvessel counting as prognostic indicators in node-negative colorectal cancer.

This manuscript reports a carefully controlled study of patients with Dukes B colorectal cancer (Dukes stage A, n=12 and Dukes stage B, n=44). Immunohistochemistry has been used to demonstrate reactivity for vascular endothelial growth factor (VEGF), and to measure levels of microvessel density (MVD) in order to assess the relationship of tumor angiogenesis with clinical outcome. Immunohistochemistry was performed using antibodies to VEGF and CD34 (for intratumoral vessel identification) and counting was performed at the invasive margin of the tumor. Results showed that for Dukes stage A patients 4/12 died of their disease, none of whose tumor was VEGF positive. In contrast, 2 patients who survived were positive for VEGF cytoplasmically, but neither showed increased tumor MVD. In Dukes B patients 10/44 died, 5 of whose tumor demonstrated VEGF reactivity, both in malignant cells and in tumor vascular endothelium. MVD ranged from 11 to 53 (median 28) for Dukes A cases and from 9 to 69 (median 32.5) for the Dukes B group. Kaplan-Meier plots and log rank test statistics for Dukes B patients demonstrated that VEGF reactivity in cells, and in tumor vascular endothelium was correlated with survival (p=0.047 and p < or = 0.06, respectively). There was a significant relationship between the presence of VEGF reactivity on vascular endothelium and outcome by Fisher's exact test (p=0.018). Similarly, by the same test VEGF positivity was significantly correlated with patient mortality (p=0.032). The presence of endothelial VEGF reactivity correlated with VEGF in malignant cells (p=0.0001) by Mann-Whitney U test and a significant inverse relationship between vessel density and patient survival was demonstrated (p = 0.019). The finding that in Dukes B patients MVD was inversely correlated with mortality supports the hypothesis that a low microvascular count is predicted close to the invasive margin, where VEGF expression is upregulated in response to hypoxia, induced by a lack of a functional vasculature. These data will be used to identify cohorts of patients who have a high risk of relapse and can be selected for adjuvant therapies such as VEGF antibody or antitumor antibody-directed therapy.

Higher dose and dose-rate in smaller tumors result in improved tumor control.

Small tumors are more sensitive to radioimmunotherapy (RIT) than larger ones. A greater proportion of viable radiosensitive areas in small tumors, higher antibody uptake, and radiation dose may be responsible. Six groups of mice with small (median tumor size 0.06 cm3) or large LoVo xenografts (median tumor size 0.38 cm3) received either RIT using a 131I-labeled anti-CEA antibody A5B7, 5-fluorouracil (5-FU) modulated with folinic acid (FA), or no treatment. The % injected activity/gram, antibody distribution in viable and necrotic areas, and dose distribution were determined. High-power microscopy images of the original section were reconstructed to estimate the proportion of viable areas. Mice with small and large tumors grew significantly less rapidly when treated with RIT compared to the control group (p < 0.0004 and p < 0.003, respectively), while 5-FU was ineffective. Small tumors treated with RIT grew less than large tumors (p < 0.02). A higher amount of % injected activity/gram of tumor (median 26.6% vs. 8.1%, p = 0.0007) and a higher dose-rate were found in small tumors at 24 hours post injection (viable areas: 56.2 +/- 23.7 vs. 13.3 +/- 7 cGy/h, necrosis 19.2 +/- 16.3 vs. 4.9 +/- 4.7 cGy/h, p = 0.0007). It appears that as viable tumor masses grow the access to them decreases and this has a fourfold effect on dose delivered for RIT in this example. These data support the consideration of use of RIT for adjuvant treatment in colon cancer.

A phase I trial of antibody directed enzyme prodrug therapy (ADEPT) in patients with advanced colorectal carcinoma or other CEA producing tumours.

Antibody-directed enzyme prodrug therapy is a targeted therapy in which a prodrug is activated selectively at the tumour site by an enzyme, which has been targeted to the tumour by an antibody (antibody-enzyme conjugate). Previous clinical trials have shown evidence of tumour response, however, the activated drug had a long half-life, which resulted in dose-limiting myelosuppression. Also, the targeting system, although giving high tumour to blood ratios of antibody-enzyme conjugate (10 000 : 1) required administration of a clearing antibody in addition to the antibody-enzyme conjugate. The purpose of this current study therefore was to attempt tumour targeting of the antibody-enzyme conjugate without the clearing antibody, and to investigate a new prodrug (bis-iodo phenol mustard, ZD2767P) whose activated form is highly potent and has a short half-life. Twenty-seven patients were treated with antibody-directed enzyme prodrug therapy using A5CP antibody-enzyme conjugate and ZD2767P prodrug, in a dose-escalating phase I trial. The maximum tolerated dose of ZD2767P was reached at 15.5 mg m(-2)x three administrations with a serum carboxypeptidase G2 level of 0.05 U ml(-1). Myelosuppression limited dose escalation. Other toxicities were mild. Patients' quality of life was not adversely affected during the trial as assessed by the measures used. There were no clinical or radiological responses seen in the study, but three patients had stable disease at day 56. Human anti-mouse antibody and human anti-carboxypeptidase G2 antibody were produced in response to the antibody enzyme conjugate (A5CP). The antibody-enzyme conjugate localisation data (carboxypeptidase G2 enzyme levels by HPLC on tumour and normal tissue samples, and gamma camera analysis of I-131 radiolabelled conjugate) are consistent with inadequate tumour localisation (median tumour: normal tissue ratios of antibody-enzyme conjugate of less than 1). A clearance system is therefore desirable with this antibody-enzyme conjugate or a more efficient targeting system is required. ZD2767P was shown to clear rapidly from the circulation and activated drug was not measurable in the blood. ZD2767P has potential for use in future antibody-directed enzyme prodrug therapy systems.

Radioimmunoguided surgery in colorectal cancer using a genetically engineered anti-CEA single-chain Fv antibody.

In radioimmunoguided surgery (RIGS), a radiolabeled antibody is given i.v. before surgery and a hand-held gamma-detecting probe is used to locate tumor in the operative field. The rapid blood clearance and good tumor penetration of single-chain Fv antibodies (scFv) offer potential advantages over larger antibody molecules used previously for RIGS. A Phase I clinical trial is reported on RIGS with scFv (MFE-23-his) to carcinoembryonic antigen (CEA). Thirty-four patients undergoing surgery for colorectal carcinoma (17 primary tumors, 16 liver metastases, and 1 anastomotic recurrence) and 1 patient with liver metastases of pancreatic carcinoma received 125I-labeled MFE-23-his scFv (125I-MFE-23-his) 24, 48, 72, or 96 h before operation. 125I-MFE-23-his showed biexponential blood clearance with alpha and beta half-lives of 0.32 and 10.95 h, respectively. The abdomen was scanned during surgery with a hand-held gamma detecting probe (Neoprobe Corp.). 125I-MFE-23-his showed good tumor localization; comparison with histology showed overall accuracy of 84%. Highest median ratios for tumor:normal tissue and tumor:blood were recorded 72 or 96 h after scFv injection for patients undergoing resection of liver metastases. High levels of radioactivity were found in the kidneys. Five patients had grade 1 fever, and three had a grade 1 rise in blood pressure according to the Common Toxicity Criteria. There was a significant correlation between these ratios and those measured in excised tissues using a laboratory gamma counter (P < 0.001). MFE-23-his scFv antibody localizes in CEA-producing carcinomas. The short interval between injection and operation, the lack of significant toxicity, and the relatively simple production in bacteria make MFE-23-his scFv suitable for RIGS.

Prognostic significance of circulating antibodies against carcinoembryonic antigen (anti-CEA) in patients with colon cancer.

OBJECTIVE: The discovery of antibodies against carcinoembryonic antigen (CEA) in patients with digestive cancers, in the late 1970s, initiated a number of studies on the role of these antibodies in patients with cancers of the GI tract. Our aim was to determine the prevalence and prognostic significance of the IgG and IgM anti-CEA antibodies in the serum of patients with colon cancer. METHODS: Using an enzyme-linked immunoassay, the sera of 58 colon cancer patients were examined for the presence of carcinoembryonic antigen (CEA) and for circulating antibodies against the CEA (anti-CEA). An inhibition assay was carried out for the determination of the specificity of the IgG and IgM anti-CEA antibodies. RESULTS: The CEA was elevated (> or =10 ng/ml) in only 12 patients (20.6%). Anti-CEA IgM and/or IgG antibodies were detected in 46 patients with colon cancer (79.1%). In the control group (n = 28), 10% of the individuals had detectable amounts of IgG and/or IgM anti-CEA antibodies. Patients with detectable amounts of circulating IgM anti-CEA antibodies (n = 14, 30.5%) had a statistically significantly better 2-yr survival compared to the rest of the patients (p = 0.017). The IgM anti-CEA antibodies can also be used as an independent prognostic factor in these patients (p = 0.0323). CONCLUSIONS: In this study, a high number of colon cancer patients have circulating anti-CEA antibodies in their sera. These may be used as diagnostic markers and as independent prognostic factors. In addition, the presence of these antibodies in the patients studied is associated with better prognosis and significantly increased 2-yr survival. It was also found that the anti-CEA antibodies (IgG and IgM) are more sensitive markers than CEA. These findings underline the biological importance of the anti-CEA antibodies and provide additional information on their potential use as markers of the immune status in patients with colon cancer.

Combined role of tumor angiogenesis, bcl-2, and p53 expression in the prognosis of patients with colorectal carcinoma.

BACKGROUND: The objective of this study was to evaluate intratumoral neoangiogenesis in Dukes Stage B and Stage C (AJCC/UICC Stage I and III) colorectal adenocarcinoma and its correlation with nuclear p53 oncoprotein accumulation and cytoplasmic bcl-2 expression as well as to assess the prognostic significance of these features in patient outcome. METHODS: Paraffin embedded specimens from 55 patients with Dukes Stage B (AJCC/UICC Stage I) and 51 patients with Dukes Stage C (AJCC/UICC Stage III) colorectal adenocarcinoma who were treated with surgery were assessed. Patients with lymph node involvement (Dukes Stage C [AJCC/UICC Stage III]) also were treated with postoperative pelvic radiotherapy and adjuvant chemotherapy with 5-fluorouracil and leucovorin with or without interferon-alpha. Immunohistochemistry was performed using the anti-CD31 monoclonal antibody (MoAb) for vessel staining, the DO7 MoAb for nuclear p53 expression, and the clone 124 for cytoplasmic/perinuclear bcl-2 expression. Patient follow-up ranged from 4-70 months (median, 28 months). RESULTS: High vascular grade (microvessel score [MS] >/= 40) was observed in 39 of 106 specimens (37%), a medium MS (16-39) was observed in 29 of 106 cases (27%), and a low MS (7-15) was observed in 38 of 106 cases (36%). Positive expression of the bcl-2 protein in > 10% of cells was observed in 33 of 106 cases (31%), whereas p53 nuclear oncoprotein accumulation in > 10% of cells occurred more frequently (44 of 106 cases [42%]). No correlation among p53 expression, bcl-2 expression, and vascular grade was observed. Stroma infiltration by CD31 positive lymphocytes was associated strongly with increased vessel density (P = 0.0001). In univariate analysis Dukes stage was the only significant prognostic parameter (P = 0.02), whereas p53 and vascular grade showed marginal prognostic significance (P = 0.07 and P = 0.09, respectively). In Dukes Stage C (AJCC/UICC Stage III) patients, high vascular grade was the only parameter that predicted a worse overall survival (P = 0.04). Double stratification showed that patients with high vascular grade and positive p53 expression had a poorer survival (P = 0.03). CONCLUSIONS: The results of the current study suggest that p53 mutations, loss of bcl-2 expression, and tumor angiogenesis are events linked to the processes of metastases and local invasion in patients with colorectal carcinoma. Increased vascularization appears to be the most important prognostic factor in patients with Dukes Stage C (AJCC/UICC Stage III) colorectal adenocarcinoma.