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Biomedical subjects

A Knuth

Publications and source records attributed to A Knuth.

At least 91 records · Page 5Linked to original sources
PubMed1995

Combination 5-fluorouracil (FU), folinic acid (FA), and alpha-interferon 2B in advanced gastric cancer: results of a phase II trial.

BACKGROUND: Based on encouraging treatment results with FU/FA or FU/IFN in gastrointestinal tract cancer, a phase II study was conducted to evaluate the effects and toxicity of combination FU/FA/IFN in patients (pts) with inoperable/metastatic gastric cancer. PATIENTS AND METHODS: IFN 6 M.U. s.c. 1 x/week, FU 500 mg/m2 bolus i.v. 1 x/week and FA 500 mg/m2 1 x/week as a 2-hour infusion. Of 72 treated pts, 72 (22 females, 50 males) are evaluable for response and toxicity. Median age was 55.6 years (28-80), and median Karnofsky performance status was 80% (70-100). Sites of measurable disease were inoperable primary tumors/local recurrence (18), liver metastasis (22), lymph nodes (31) and peritoneum (20). One pt had bone marrow metastasis and another had paraneoplastic hyperfibrinolytic coagulopathy. RESULTS: 10/72 pts had complete response, 20/72 pts partial response, 40/72 pts tumor stabilization and 2/72 pts progressive disease. The median duration of response (CR/PR) was 9 months, the median progression-free interval 6 months, the median survival time was 9 months, and for responding patients (CR/PR) 12.5 months. TOXICITY: 1/72 pts had WHO grade 4 toxicity (diarrhea), 5/72 pts had WHO grade 3 toxicity (nausea 1, diarrhea 4). Except for 1 treatment-limiting grade 4 toxicity, no modifications of dose or schedule due to toxicity were required. Thirty-six of 44 pts experienced a significant reduction in tumor-related pain under treatment. CONCLUSION: Biochemical modulation of FU with FA and IFN is effective in advanced gastric cancer. Moderate toxicity, outpatient treatment setting and high rates of amelioration tumor-related pain contribute to an effective palliation.

Adult↗
PubMed1994

Frequency analysis of tumor-reactive cytotoxic T lymphocytes in peripheral blood of a melanoma patient vaccinated with autologous tumor cells.

A limiting-dilution assay was developed and used to determine the frequency of autologous tumor-reactive cytotoxic T lymphocytes (CTL) in peripheral blood of a melanoma patient MZ2, who has been free of detectable disease since several years. In this patient, the frequencies of tumor-reactive CTL spontaneously varied only by a factor of 1.5. After vaccinations with autologous mutagenized and lethally irradiated tumor cells a two- to tenfold increase in frequencies of tumor-reactive CTL was found within the first 2 weeks. Thereafter, CTL frequencies returned to values measured prior to vaccinations. We conclude, that the limiting-dilution assay applied in this study can detect changes in the T cell response to autologous tumor cells. The frequency of tumor-reactive CTL determined with this approach can serve as an immunological parameter for monitoring the T cell response to autologous tumor cells in individual cancer patients receiving tumor cell vaccinations.

Cells, Cultured↗
PubMed1994

Induction of tumour cell lysis by a bispecific antibody recognising epidermal growth factor receptor (EGFR) and CD3.

A bispecific antibody construct (bAb) recognising CD3 and epidermal growth factor receptor (EGFR) was studied in vitro. Human peripheral blood lymphocytes (PBL), pre-activated with monoclonal antibody OKT-3 or with irradiated tumour cells, were armed with the bAb construct and targeted to autologous and allogeneic tumour target cells in culture. bAb EGFR x CD3 promoted significant cytolysis even at a concentration of 1 ng/ml. The specificity of target cell lysis was provided by the EGFR specificity of the bAb, as tumour cells negative for EGFR were not lysed. However, not only EGFR-positive tumour cells but also EGFR-positive normal cells were killed. Human renal cancer cell lines and the normal autologous kidney cell cultures expressing the same level of EGFR molecules were lysed to a similar extent. These results may contribute toward the planning of future clinical trials with such bAb.

Antibodies, Bispecific↗
PubMed1994

Effect of ursodeoxycholic acid on intracellular pH in a bile duct epithelium-like cell line.

Recent studies in perfused livers and isolated hepatocytes indicate that ursodeoxycholic acid-induced HCO3-rich hypercholeresis originates at the ductule/duct level. The bile duct epithelium may be involved in bile alkalinization by passively reabsorbing the protonated unconjugated ursodeoxycholic acid, by directly secreting in response to an ursodeoxycholic acid-induced increase in acid/base transporter activity or by taking up UDCA- in exchange for a base equivalent. To investigate these processes in more detail, we studied the effects of ursodeoxycholic acid on intracellular pH in SK-ChA-1, a well-differentiated human cholangiocarcinoma cell line similar to bile duct epithelium in terms of intracellular pH regulatory mechanisms and morphological markers. Intracellular pH changes were monitored with a microfluorimetric setup using the fluorescent indicator 2'-7'-bis(2-carboxyethyl)-5,6,carboxy fluorescein. Administration of 50 to 1,000 mumol/L UDCA in the absence of HCO3 caused dose-dependent intracellular acidification (intracellular pH = -0.13 +/- 0.03 pH/U after 500 mumol/L ursodeoxycholic acid). Acidification was not prevented by preincubation of cells with 0.5 mmol/L 4,4-diisothiocyanatostilbene-2,2,-disulfonic acid (DIDS) for 30 min or by furosemide administration (1 mmol/L), thus ruling out the stimulation of Cl/HCO3 exchange or the presence of an ursodeoxycholic acid/base exchange. Ursodeoxycholic acid also acidified human fibroblasts, a cell type with no transport capability for ursodeoxycholic acid. In addition, direct measurement of the activities of the three major acid/base transporters in Sk-ChA-1 cells (Na+/H+ exchange, sodium-dependent and sodium-independent Cl/HCO3 exchange) failed to show significative differences between cells treated with 500 mumol/L UDCA and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1993

Induction of tumor-cell lysis by bi-specific antibody recognizing ganglioside GD2 and T-cell antigen CD3.

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.

Antibodies↗
PubMed1993

Analysis of antigens recognized on human melanoma cells by A2-restricted cytolytic T lymphocytes (CTL).

We have pursued our analysis of potential tumor-rejection antigens recognized on human melanoma by autologous cytolytic T lymphocytes (CTL). We reported previously that 3 distinct antigens (A,B,C) were recognized on melanoma cell line SK29-MEL in association with HLA-A2. Selection for melanoma-cell variants resistant to anti-A CTL revealed that antigen A consists of at least 2 determinants (Aa, Ab) which can be lost separately. Genetic linkage between Aa and Ab was suggested by concomitant loss of Aa and Ab in an immunoselected tumor-cell variant. This variant was also resistant to an autologous CTL clone restricted by HLA-B45, indicating that this CTL may also recognize a determinant of antigen A. Of 11 allogeneic HLA-A2 melanoma cell lines that were tested, 5 expressed both Aa and Ab, 1 expressed only Aa, and 1 only Ab. None of them was lysed by anti-B or anti-C CTL clones. A CTL clone derived from another HLA-A2-melanoma patient was found to have exactly the same lytic pattern as the anti-Ab CTL of the first patient. This suggested that it may be possible to elicit an anti-Ab response in many HLA-A2 patients. We conclude that there are at least 2 distinct antigens presented in association with HLA-A2 that are common to many melanomas and therefore constitute promising targets for specific immunotherapy.

Antigens, Neoplasm↗
PubMed1993

Lysis of human pancreatic adenocarcinoma cells by autologous HLA-class I-restricted cytolytic T-lymphocyte (CTL) clones.

From the primary site of a pancreatic adenocarcinoma (patient BE) a permanent cell line (MZ-PC-2) was established in tissue culture. In the course of mixed lymphocyte-tumor-cell cultures (MLTC) with autologous blood-derived lymphocytes, we isolated CTL clones that lysed autologous tumor cells but not autologous EBV-transformed B cells (EBV-B) and not K562. Pre-treatment of MZ-PC-2 cells with IFN-gamma was required to obtain significant lysis in 4-hr cytotoxicity assays. IFN-gamma was superior to IFN-alpha in that respect. Among MLTC responder lymphocytes, tumor-reactive CTL proliferated more strongly in response to MZ-PC-2 cells treated with IFN-gamma than to untreated tumor cells. Three CTL clones derived from MLTC were chosen for further analysis. They were CD3+, CD8+, TCR-alpha/beta+ and behaved identically in all functional aspects tested. They all expressed the same TCR-beta chain, indicating that they descended from a common precursor lymphocyte and were directed against the same antigen. According to antibody-inhibition experiments, BE-CTL recognized their targets via an HLA-B molecule carrying the Bw6 supertypic determinant. Irrespective of pre-incubation with IFN-gamma, low levels of tumor-cell lysis, or none, were seen when MZ-PC-2 cells were kept in medium supplemented with autologous serum or serum pooled from healthy volunteers instead of FCS. Lysability was restored when TNF-alpha was added to human serum. Serum-free medium was found to enhance the susceptibility of MZ-PC-2 cells to lysis by autologous CTL.

Adenocarcinoma↗
PubMed1992

Sequential methotrexate and 5-fluorouracil (FU) vs. FU alone in metastatic colorectal cancer. Results of a randomized multicenter trial. The Association of Medical Oncology (AIO) of the German Cancer Society.

Methotrexate (MTX) modulates 5-fluorouracil (FU) in several in vitro and in vivo experimental systems. Results of phase II studies have suggested improved response rates for the sequential application of MTX and FU in colorectal cancer. In a prospective randomized multicenter study we compared sequential MTX (300 mg/m2) and FU (900 mg/m2) using a seven-hour time interval and leucovorin rescue with FU (450 mg/m2/d for five days) in patients with previously untreated metastatic colorectal cancer. Of 172 patients randomized 159 were eligible for survival analysis and 153 for toxicity and response evaluation. Complete or partial response has been seen in 25.3% of patients receiving sequential MTX and FU and in 17.6% of those receiving FU alone (p = 0.11). There have been two long-term survivors, apparently cured by MTX/FU. Overall toxicity was more pronounced with FU alone, but sequential MTX/FU caused four toxic deaths. Median survival and survival rates at one and two years were not significantly different. It is concluded that this schedule of sequential MTX and FU is no more effective than a dose-intensive treatment with FU alone in metastatic colorectal cancer.

Adult↗
PubMed1992

T cell responses to human malignant tumours.

The immunological and molecular mechanisms that govern T cell responses to human malignant tumours are just starting to be understood within a more complex framework of humoral, cellular and molecular interactions. The definition of multiple antigens simultaneously expressed on human melanoma, as detected with cytolytic T cells in immunoselection experiments, is a first step towards the molecular characterization of these antigens. Observations on the influence of expression of restriction elements of the major histocompatibility complex on the recognition of these tumour associated antigens have advanced our understanding of how the immune system responds to cancer cells in vivo. It is specificity that is tuning the immune system, not only in cancer. The molecular characterization of the first human cancer antigen recognized by CTL is now under way as outlined by Boon et al in this issue.

Antigens, Neoplasm↗
PubMed1992

Treatment of refractory colorectal carcinomas with fluorouracil, folinic acid, and interferon alfa-2a.

Interferon has been shown to augment the cytotoxic effects of fluorouracil (5-FU) against colon cancer in vitro and possibly in vivo. Therefore a pilot study was initiated to evaluate the effects of the combination 5-FU/FA/interferon alfa (IFN-alpha) in colorectal adenocarcinomas refractory to first-line therapy with 5-FU/FA. Eleven patients with rectum cancer and four patients with colon cancer were treated according to the following schedule: 9 million units IFN-alpha subcutaneous three times a week; 500 mg/m2 5-FU via an intravenous bolus 1 hour after the initiation of a 2-hour infusion of 500 mg/m2 of FA, once a week. Of 15 patients, one had a minor response, one had a disease stabilization, and three had a mixed response. No complete or partial remissions were seen. Looking at the sensitivity of lung metastases (three of three), the regressions can be explained through the additive effect of IFN-alpha to 5-FU/FA. Although minimal side effects (World Health Organization classification) were observed, most patients experienced a reduction of well-being.

Adult↗
PubMed1992

Combination fluorouracil, folinic acid, and interferon alfa-2a: an active regimen in advanced pancreatic carcinoma.

Based on promising results with 5-FU/FA or 5-FU/IFN-alpha in colorectal cancer, a pilot study was initiated to evaluate the effects of the combination 5-FU/FA/interferon alfa (IFN-alpha) in patients with advanced pancreatic cancer. Patients received 9 million units (MU) IFN-alpha subcutaneously three times a week or 6 MU IFN-alpha once a week; 500 mg/m2 5-FU via an intravenous bolus 1 hour after the initiation of a 2-hour infusion of 500 mg/m2 of FA, once a week. Fourteen patients, all previously untreated with chemotherapy, were enrolled; 13 (two females/11 males) were evaluable for response and toxicity (one too early). The median performance status was 80% (range, 60 to 100) and the median age 62 years. Besides the inoperable primary tumor, metastatic sites were liver, lung, and peritoneum. Three of 13 patients had a partial remission, three of 13 patients a minor response, and four of 13 patients no change. Three patients had progressive disease. Until now, no complete remission was seen. Median duration of response was 4+ months; median survival has not been reached yet. Of all patients there were three instances of World Health Organization grade 3 toxicity: fatigue (one of 13), nausea (one of 13), and diarrhea (one of 13); grade 4 toxicity did not occur. Although overall toxicity was moderate, most patients experienced a reduction of well-being. Therefore in all patients the dose of IFN was reduced (from 3 x 9 MU/week to 1 x 6 MU/week). Our preliminary data suggest that biochemical modulation of 5-FU with FA and IFN-alpha (reduced dosage) is effective in pancreatic cancer with moderate toxicity, warranting further study.

Adult↗
PubMed1991

A gene encoding an antigen recognized by cytolytic T lymphocytes on a human melanoma.

Many human melanoma tumors express antigens that are recognized in vitro by cytolytic T lymphocytes (CTLs) derived from the tumor-bearing patient. A gene was identified that directed the expression of antigen MZ2-E on a human melanoma cell line. This gene shows no similarity to known sequences and belongs to a family of at least three genes. It is expressed by the original melanoma cells, other melanoma cell lines, and by some tumor cells of other histological types. No expression was observed in a panel of normal tissues. Antigen MZ2-E appears to be presented by HLA-A1; anti-MZ2-E CTLs of the original patient recognized two melanoma cell lines of other HLA-A1 patients that expressed the gene. Thus, precisely targeted immunotherapy directed against antigen MZ2-E could be provided to individuals identified by HLA typing and analysis of the RNA of a small tumor sample.

Antigens, Neoplasm↗
PubMed1991

A human renal cancer line as a new antigen source for the detection of antibodies to cytoplasmic and nuclear antigens in sera of patients with Wegener's granulomatosis.

Autoantibodies directed against cytoplasmic antigens of neutrophils (ANCA), especially proteinase 3 (C-ANCA), have proved to be a useful clinical tool to support the diagnosis or to monitor disease activity in Wegener's granulomatosis (WG). Till now, human neutrophil granulocytes have represented the major antigen source used to detect antibodies in WG by the immunofluorescence technique (IFT). We have tested serum samples of 164 patients with different connective tissue diseases (50 suffering from clinically active WG) performing IFT on a human renal cancer line (SK-RC11) and have found antibodies against the nuclear and cytoplasmic antigens in 39 patients. C-ANCA+ sera displayed a characteristic diffuse cytoplasmic staining pattern. Antibody titers measured with human granulocytes were comparable to titers obtained using culture cells. Antibody binding could be inhibited by preabsorption with an extract of human granulocytes or purified proteinase 3. A protein of 29 kDa MW could be isolated by affinity purification using a SK-RC11 extract and a high-titer C-ANCA+ serum and antigenic identity was further confirmed by IFT using a monoclonal antibody to proteinase 3. Treatment of tumor cells with cytokines (interferon, tumor necrosis factor) led to a time dependent translocation of the antigen into the nucleus and back to the cytoplasm. The antigen was also expressed on the surface of live cells colocalized with MHC II. In addition, 21 WG patients had antibodies to cytoplasmic organelles identified by laser scanning microscopy as secretory vesicles of the Golgi complex, and five had antibodies to nuclear antigens. This is, to the best of our knowledge, the first report of proteinase 3 in human non-leukemic cells. Our data demonstrate, that the repertoire of antigens recognized by antibodies in WG sera is not limited to human neutrophils and monocytes and indicates a possible functional role of the antigenic proteins.

Antibodies, Antinuclear↗
PubMed1991

Cellular and humoral immune responses against cancer: implications for cancer vaccines.

The key issue in tumor immunology is to identify antigens as target structures for a cancer-selective immunological attack in the tumor-bearing host, resulting in tumor rejection. There is a growing detailed understanding of structural and regulatory gene alterations giving rise to candidate rejection antigens and peptides in tumor cells. As well as reviewing the development of new adjuvant and recombinant vector systems, new approaches are suggested for the construction of cancer vaccines.

Animals↗
PubMed1991

[Malignant melanoma of the mucous membranes of the upper aerodigestive tract. Clinical, histological and immunohistochemical characteristics].

Malignant melanomas of the mucous membranes are rare tumors. They make up about 10% of all malignant melanomas of the head and neck; 15 of the authors' cases are reviewed in this article. Six of these had neck lymph node metastasis when first diagnosed. The tumors were surgically removed in all patients. Thirteen patients developed at least one tumor recurrence, ten patients distant metastasis. Eight patients died of the tumor condition; the mean survival time of all patients was 33.4 months. While the tumors could be classified histologically into four types, this had no bearing on the course of the disease. In many cases, primary tumor and metastasis or recurrent tumor differed histologically. Melanin pigment was found in 13 tumors. Mucosal melanomas can be regarded as a discrete tumor entity because their biological behavior differs from that of malignant melanomas of the skin. However there are no morphological differences between the two tumor entities. Ophthalmological and dermatological examinations must be performed in all patients with mucosal melanoma to exclude metastasis of the skin or choroid melanoma.

Adult↗