Evaluation of cytokeratin 19 fragment (CYFRA 21-1) as a tumor marker in malignant pleural effusion.
(41/2094)
BACKGROUND: The aim was to investigate the diagnostic utility of CYFRA 21-1 (cytokeratin 19 fragment) as a tumor marker in pleural effusion and evaluate the value of combining CYFRA 21-1 and carcinoembryonic antigen (CEA) assays as a diagnostic aid in the malignant pleural effusion. METHODS: One hundred and twenty-six patients (72 malignant and 54 benign pleural effusion) were included in this retrospective study. The effusion levels of CYFRA 21-1 and CEA were measured using radioimmunometric assay. RESULTS: The median values of CYFRA 21-1 in benign and malignant pleural effusion are 15 and 70 ng/ml, respectively. Using a cut-off value of 50 ng/ml, defined at 94% specificity, the diagnostic sensitivity of CYFRA 21-1 for non-small cell lung carcinoma (n = 61), squamous cell carcinoma (n = 21), adenocarcinoma (n = 40) and small cell lung cancer (n = 11) was 64, 71, 60 and 18%, respectively. Regardless of cell types, the diagnostic sensitivity of CYFRA 21-1 and CEA in malignant pleural effusion (n = 72) was 57 and 60%, respectively (cut-off value of 10 ng/ml in CEA assay). Combining CEA with CYFRA 21-1, the diagnostic sensitivity may increase up to 72%, which was defined at 89% specificity. CONCLUSION: CYFRA 21-1 assay may be a useful tumor marker for discriminating benign from malignant pleural effusion, especially in those of non-small cell lung cancer. The combined use of CEA and CYFRA 21-1 assay in the malignant effusion may increase the diagnostic yield compared with CEA or CYFRA 21-1 alone. (+info)
Dosimetric evaluation and radioimmunotherapy of anti-tumour multivalent Fab' fragments.
(42/2094)
We have been investigating the use of cross-linked divalent (DFM) and trivalent (TFM) versions of the anti-carcinoembryonic antigen (CEA) monoclonal antibody A5B7 as possible alternatives to the parent forms (IgG and F(ab')2) which have been used previously in clinical radioimmunotherapy (RIT) studies in colorectal carcinoma. Comparative biodistribution studies of similar sized DFM and F(ab')2 and TFM and IgG, radiolabelled with both 131I and 90Y have been described previously using the human colorectal tumour LS174T nude mouse xenograft model (Casey et al (1996) Br J Cancer 74: 1397-1405). In this study quantitative estimates of radiation distribution and RIT in the xenograft model provided more insight into selecting the most suitable combination for future RIT. Radiation doses were significantly higher in all tissues when antibodies were labelled with 90Y. Major contributing organs were the kidneys, liver and spleen. The extremely high absorbed dose to the kidneys on injection of 90Y-labelled DFM and F(ab')2 as a result of accumulation of the radiometal would result in extremely high toxicity. These combinations are clearly unsuitable for RIT. Cumulative dose of 90Y-TFM to the kidney was 3 times lower than the divalent forms but still twice as high as for 90Y-IgG. TFM clears faster from the blood than IgG, producing higher tumour to blood ratios. Therefore when considering only the tumour to blood ratios of the total absorbed dose, the data suggests that TFM would be the most suitable candidate. However, when corrected for equitoxic blood levels, doses to normal tissues for TFM were approximately twice the level of IgG, producing a two-fold increase in the overall tumour to normal tissue ratio. In addition RIT revealed that for a similar level of toxicity and half the administered activity, 90Y-IgG produced a greater therapeutic response. This suggests that the most promising A5B7 antibody form with the radionuclide 90Y may be IgG. Dosimetry analysis revealed that the tumour to normal tissue ratios were greater for all 131I-labelled antibodies. This suggests that 131I may be a more suitable radionuclide for RIT, in terms of lower toxicity to normal tissues. The highest tumour to blood dose and tumour to normal tissue ratio at equitoxic blood levels was 131I-labelled DFM, suggesting that 131I-DFM may be best combination of antibody and radionuclide for A5B7. The dosimetry estimates were in agreement with RIT results in that twice the activity of 131I-DFM must be administered to produce a similar therapeutic effect as 131I-TFM. The toxicity in this therapy experiment was minimal and further experiments at higher doses are required to observe if there would be any advantage of a higher initial dose rate for 131I-DFM. (+info)
A triad of costimulatory molecules synergize to amplify T-cell activation.
(43/2094)
The activation of a T cell has been shown to require two signals via molecules present on professional antigen-presenting cells: signal 1, via a peptide/MHC complex; and signal 2, via a costimulatory molecule. Here, the role of three costimulatory molecules in the activation of T cells was examined. Poxvirus (vaccinia and avipox) vectors were used because of their ability to efficiently express multiple genes. Murine cells provided with signal 1 and infected with either recombinant vaccinia or avipox vectors containing a TRIad of COstimulatory Molecules (B7-1/ICAM-1/LFA-3, designated TRICOM) induced the activation of T cells to a far greater extent than cells infected with any one or two costimulatory molecules. Despite this T-cell "hyperstimulation" using TRICOM vectors, no evidence of apoptosis above that seen using the B7-1 vector was observed. Results using the TRICOM vectors were most dramatic under conditions of either low levels of first signal or low stimulator cell:T-cell ratios. Experiments using a four-gene construct also showed that TRICOM recombinants can enhance antigen-specific T-cell responses in vivo. These studies thus demonstrate for the first time the ability of vectors to introduce three costimulatory molecules into cells, thereby activating both CD4+ and CD8+ T-cell populations to levels greater than those achieved with the use of only one or two costimulatory molecules. This new threshold of T-cell activation has broad implications in vaccine design and development. (+info)
Analysis of the human carcinoembryonic antigen promoter core region in colorectal carcinoma-selective cytosine deaminase gene therapy.
(44/2094)
We isolated a 204-base pair carcinoembryonic antigen (CEA) promoter core region from a CEA-producing human colorectal carcinoma (CRC) and constructed retrovirus vectors carrying the expression cassette consisting of the CEA promoter core region and the cytosine deaminase (CD) gene. pCD2 retrovirus carrying the CD gene directed by the retrovirus long terminal repeat promoter served as a control vector. An in vitro study showed that the CEA promoter conferred CEA-producing cell-selective CD expression, specifically when the CD expression cassette was inserted into the 3' long terminal repeat of the retrovirus vector. CD-modified CRC xenografts in nude mice were sensitive to 5-fluorocytosine and caused a profound bystander effect on the unmodified CRC. When nude mice harboring intraperitoneally disseminated CRCs were injected intraperitoneally with the CD expression cassette-carrying retrovirus-producing cells, CD transduction into the disseminated CRCs and bone marrow (BM) was observed. CD expression was, however, restricted to CRCs, and it was observed in both CRCs and BM of mice injected with pCD2 retrovirus-producing cells, resulting in better therapeutic outcomes without BM suppression. These results indicate that effective and safe in vivo gene therapy for CRC may be feasible by transferring the CD gene controlled by the CEA promoter core region. (+info)
The significance of NSE and CEA as a differentiation marker for the cellular heterogeneity of small cell lung cancer.
(45/2094)
Neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) levels in the culture supernatant of the 65 pulmonary carcinoma cell lines: Small cell lung cancer (SCLC) 18, large cell carcinoma 14, squamous cell carcinoma 14, adenocarcinoma 14 and adenosquamous cell carcinoma 5, were measured by a radioimmunoassay (RIA). The mean value of NSE was 30.8+/-22.4 ng/ml and 9.2+/-8.7 ng/ml in SCLC and non-SCLC, respectively. The mean value of CEA was 15.1+/-20.9 ng/ml and 26.6+/-72.3 ng/ml in SCLC and non-SCLC, respectively. A significant difference in NSE levels was obtained between SCLC cell lines and non-SCLC cell lines. In SCLC cell lines, a significant inverse proportional correlation was observed between NSE and CEA levels. The CEA production tended to be higher in cells with low levels of NSE than in those with high NSE production. With respect to correlation between marker production and growth characteristics of SCLC cells in vitro, significantly higher NSE and lower CEA levels were found in cells growing with floating colony or neurite like characteristics (classic cell type) than those in cells with epithelial or intermediate growth characteristics (variant cell type). A significant positive correlation between NSE levels and the survival periods was found in follow-up studies of 10 patients who underwent surgery with complete resection of the primary tumor. All of 4 long term survivors over 3 years after surgery had significantly high NSE and relatively low CEA producing tumors. The relationship of these markers to clinical status of the patient suggests that an analysis for correlation of NSE and CEA levels in SCLC patients may be useful to discriminate between a pure neuroendocrine SCLC tumor and a mixed small cell/large cell tumor, and in monitoring therapeutic effect and prognosis of each patient. (+info)
Bypassing immunization: optimized design of "designer T cells" against carcinoembryonic antigen (CEA)-expressing tumors, and lack of suppression by soluble CEA.
(46/2094)
Tumor-associated antigens are typically nonimmunogenic in cancer patients, "immune surveillance" having manifestly failed. The fact that most tumor antigens are normal human proteins presents significant obstacles to current cancer immunization approaches that researchers are presently striving to overcome. An alternative strategy bypasses immunization altogether by direct genetic alteration of autologous patient T cells, to create "designer T cells" specific to a particular antigen. Chimeric immunoglobulin-T cell receptors (IgTCR) with a specificity for carcinoembryonic antigen (CEA) were created to evaluate the optimal IgTCR structure for cancer therapy. Antigen-binding domains of a humanized antibody were combined with TCR signaling chains to yield four different chimeric IgTCR: single chain Fv fragment (sFv)-zeta, fragment antigen-binding (Fab)-zeta, sFv-epsilon, and Fab-epsilon. All of the IgTCR were well expressed on T cells, and all showed specific binding and activation, as demonstrated by IL-2 production on contact with immobilized or cellular CEA, excepting sFv-epsilon alone which was inert solely against cellular targets for steric reasons unique to this construct. In contrast to prior studies of isolated TCR chains that related increased tyrosine-based activation motifs in zeta as a reason for superior signaling potency, these tests are the first to show that epsilon and zeta are indistinguishable for T cell signaling when assayed in the context of the intact TCR complex. Further, Fab was equivalent to sFv as an IgTCR component for expression and antigen binding, establishing an important alternative for IgTCR antigen recognition because sFvs may often lose antigen affinity. When IgTCR was expressed on normal human T cells, cytotoxic potency was demonstrated at low E:T ratios, with T cell recycling and progressive tumor cell destruction. Contrary to recent speculations, these observations prove that high affinity TCR interactions are not an impediment to serial target engagement and disengagement by cytotoxic T cells. The multivalent intercellular interactions of target cell binding, activation, and cytotoxicity were resistant to inhibition by soluble CEA. These studies establish a potentially important new immunotherapeutic modality for the treatment of CEA-expressing tumors. (+info)
Increased detection of circulating tumor cells in the blood of colorectal carcinoma patients using two reverse transcription-PCR assays and multiple blood samples.
(47/2094)
The objectives of this study were to assess whether the use of two reverse transcription-PCR (RT-PCR) cDNA assays and multiple blood sampling increased circulating tumor cell detection in colorectal cancer patients. Systemic blood was sampled three times at 1-min intervals in 100 colorectal cancer patients (50 primary tumors only and 50 liver metastases), and in 70 control patients without known cancer. After removal of the erythrocytes, samples were subjected to separate RT-PCR reactions using specific primers for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20). Statistical analysis was performed by the two-sample binomial test and the one-sided McNemar test. There were significant increases in circulating tumor cell positivity when CEA and CK20 assays were used together as compared with either CEA or CK20 assay used alone. There were also significant increases in circulating tumor cell positivity for either CEA or CK20 assay used alone when the results from two blood samples were compared with the results from one sample. Circulating colorectal cancer cell positivity rose from 48% (CEA) and 34% (CK20) with one assay of one sample to 74% when both assays of three samples were used to identify circulating tumor cells. Three non-cancer control patients (4.3%) were positive for either CEA (two patients) or CK20 (one patient). Tumor cells were identified more frequently in the circulation of colorectal cancer patients than had been suggested previously. RT-PCR-based studies of the clinical significance of circulating cancer cells in colorectal cancer should involve multiple blood samples with identification of multiple tumor-related cDNA products. (+info)
Cancer-associated isoenzyme of serum galactosyltransferase.
(48/2094)
Galactosyltransferase activity was assayed in sera from 58 patients with various types of cancer. On discontinuous polyacrylamide gel electrophoresis a slow-moving peak of galactosyltransferase activity (isoenzyme II) was found to be present in the serum of 43 of these patients in addition to the major isoenzyme I. Isoenzyme II was found in only 2 of 39 patients with various nonmalignant disorders and was not detected in the serum of 22 normal control subjects. There was no correlation between the presence of this electrophoretically distinct isoenzyme and total serum galactosyltransferase activity, alkaline phosphatase, levels of carcinoembryonic antigen, or blood type. However, patients with widespread metastases had significantly higher isoenzyme II levels than those with no metastases or with limited local spread. Further studies will be necessary to evaluate the clinical usefulness of this serum galactosyltransferase isoenzyme in the diagnosis and monitoring of patients with neoplastic disease. (+info)