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Annals of the New York Academy of Sciences 12/2006; 804(1):341 - 361. · 3.15 Impact Factor
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ABSTRACT: During the last decade, several studies have evaluated the treatment of chronic phase chronic myeloid leukemia (CML) with a combination of interferon (IFN)-alpha and low- dose cytarabine (Ara-C). This combination therapy has been shown to be superior compared to monotherapy with IFN-alpha in randomized studies with regard to hematologic and cytogenetic remissions. However, the survival benefit is small, and the toxicity of the combination therapy is high. This paper reviews the published studies on IFN-alpha/low-dose Ara-C for the treatment of chronic phase CML and discusses the value of the combination therapy.
Leukemia and Lymphoma 06/2001; 41(5-6):523-33. · 2.58 Impact Factor
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M Lindauer,
D Domkin,
H Döhner,
H J Kolb,
A Neubauer,
D Huhn,
H Kreiter,
B Koch,
C Huber,
W Aulitzky,
T Fischer
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ABSTRACT: Newly diagnosed chronic myelogenous leukaemia (CML) patients (n = 65) were treated with interferon (IFN)-alpha2b (5 x 106 IU/d s.c.) combined with monthly courses of cytarabine (20 mg/d s.c. for 14 d). Median age of patients enrolled was 45 years. The endpoints of the study were clinical efficacy and toxicity. The survival rates at 3 years and 5 years were 77% and 56%, respectively. The rate of complete haematological response was 60%. Evaluation of cytogenetic response was available in 29/65 patients. A complete cytogenetic response was seen in 3/29 patients (10%). W.H.O. toxicity grade 3-4 occurred in only 22/523 evaluable treatment cycles. Since the study protocol required intermittent or definitive discontinuation of cytarabine in case of moderate leucopenia (white blood cells (WBC) <5 x 109/l), combined cytopenia (WBC < 5 x 109/l, platelets <100 x 109/l), and isolated moderate thrombocytopenia (<100 x 109/l), the drug had to be discontinued temporarily or definitively in 200 cycles and the dose of cytarabine had to be reduced in 35 cycles. Thus, only 25% of the planned dose of cytarabine could be administered. At this dosage it would appear that cytarabine had no effect on survival and did not improve remission rates. We conclude that a clinical benefit for the addition of cytarabine to the treatment of CML with IFN might only be achieved by the administration of a higher cumulative dose of cytarabine, suggesting that lower leucocyte counts of 2-4 x 109/l have to be tolerated.
British Journal of Haematology 10/1999; 106(4):1013-9. · 4.94 Impact Factor
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ABSTRACT: Colorectal cancer is considered a non-immunogenic malignany. One strategy to augment the immunogenicity of such tumours is represented by the expression of costimulatory molecules by gene transfer. Using transfected variants of the human colorectal cancer cell line SW480 we tested various costimulatory molecules (CD80, CD86, CD54) and a class II major histocompatibility complex (MHC) allele (HLA-DR3) alone or in combination on their ability to support primary T-lymphocyte activation in vitro. Expression of CD80 or CD86 similarly as the combination of both was not sufficient to induce proliferation of human allogeneic T cells. Expression of CD54 together with CD80 strongly augmented the costimulatory function of CD80, as observed in the presence of a CD3 monoclonal antibody (mAb), but did not lead directly to a T-cell response against modified tumour cells. Importantly, SW480 cells coexpressing CD54, CD80 and the HLA-DR3 allele effectively promoted T-lymphocyte proliferation. Moreover, the use of such CD54+/CD80+/HLA-DR3+ SW480 variants for repetitive stimulations resulted in the generation of T-cell lines predominantly composed of CD8+ T cells exhibiting class I MHC restricted cytolytic activity towards untransfected SW480 tumour cells. This demonstrates that the generation of immunogenic tumour cell variants, i.e. for the use as cellular vaccines, requires multiple genetic alterations in the case of non-immunogenic human tumours cells, such as colorectal cancer cells.
Immunology 04/1998; 93(3):390-7. · 3.32 Impact Factor
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ABSTRACT: The disappointing clinical results of cancer immunotherapy of the past few decades have not diminished the optimism about the potential of the new generation of immunotherapeutic strategies towards treatment of malignant disease. Tremendous progress has been made over recent years in unveiling the molecular basis of antigen presentation and recognition by cytotoxic T lymphocytes (CTL). The molecular concepts that have emerged from these studies have led to the design of novel anticancer vaccines and CTL-based immunotherapeutics. This review is to highlight the current molecular insights of antigen presentation and CTL recognition/activation, and their impact on the rational design of therapeutic interventions that may result in protective, CTL-based antitumor immunity.
Journal of Molecular Medicine 02/1998; 76(1):32-47. · 4.67 Impact Factor
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Recent results in cancer research. Fortschritte der Krebsforschung. Progrès dans les recherches sur le cancer 02/1998; 144:78-85.
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ABSTRACT: Introduction of co-stimulatory molecules like CD80 and CD86 represents a means to augment the immunogenicity of tumor cells and to induce immune responses directed at tumor antigens. Here we compared CD80- and CD86-transfected human melanoma cells to induce primary immune responses by their capacity to promote proliferation of human allogeneic resting T lymphocytes. CD80- and CD86-transfected SkMel63 melanoma cells induced T cell activation to a comparable degree, which was found to be independent of the cell surface density of these co-stimulatory molecules. Co-expression of CD80 and CD86 did not result in a synergistic increase in T cell proliferation. Both CD80 and CD86 transfectants induced the proliferation of isolated CD4+ or CD8+ T cells. Exogenous IL-2, IL-4 and tumor necrosis factor-alpha respectively enhanced primary T cell proliferation independent of CD80 or CD86 expression. Interestingly, differential activities of CD80 and CD86 were observed following stimulation of resting T cells in the presence of IL-12. Whereas IL-12 increased T cell proliferation in the presence of CD86-transfected melanoma cells, it exhibited an inhibitory function in the presence of CD80-expressing SkMel63 cells. Experimental evidence indicates that this inhibitory effect was mediated by IFN-gamma since (I) IFN-gamma secretion of stimulated T cells was augmented by IL-12, (II) exogenous IFN-gamma also inhibited T cell proliferation induced by CD80- but not CD86-transfected SkMel63 cells and (III) the inhibitory effect of IL-12 was blocked by an anti-IFN-gamma mAb.
International Immunology 07/1997; 9(6):853-60. · 3.41 Impact Factor
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Annals of the New York Academy of Sciences 01/1997; 804:341-61. · 3.15 Impact Factor
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ABSTRACT: One aim of the genetic modification of tumor cells is the generation of immunogenic variants that can be used for the induction of immune responses against tumors. We engineered the human colorectal carcinoma cell line SW480 by means of plasmid transfection to secrete interleukin (IL)-2. Transfection of SW480 cells resulted in stable IL-2 secretion at 5-30 ng/ml per 10(5) cells in 24 h and, unexpectedly, in CD54 expression on the cell surface. SW480 variants expressing IL-2 and CD54 were tested for their capacity to induce T lymphocyte activation in vitro in comparison to untransfected and CD54 transfected cells. The cytolytic effector function of a class I MHC restricted CD8+, peptide antigen specific T cell clone was augmented following expression of CD54. IL-2 secreting SW480 variants did not further increase antigen-dependent cytolysis. Primary activation of resting T lymphocytes was assessed following allogeneic stimulation. When compared with unmodified SW480 cells, CD54 expressing variants did not initiate T cell proliferation. In contrast, IL-2 secreting SW480 cells strongly promoted primary T cell proliferation. Similarly, exogenous IL-2 and SW480 cells induced T cell proliferation which was not only due to IL-2 but was dependent on tumor cells. However, following the initial wave of cell growth in response to IL-2 secreting SW480 cells T lymphocytes could not be restimulated with SW480 or IL-2 secreting variants and could not be further expanded. T cells initially activated by IL-2 secreting SW480 cells exhibited cytolytic activity towards SW480 cells. This reactivity, however, was transient and completely blocked by K562 cells, suggesting MHC-unrestricted, nonspecific cytotoxicity. We conclude that endogenous IL-2 secretion by the colorectal carcinoma cell line SW480 does not result in the activation of MHC restricted specific T lymphocytes but predominantly induces lymphokine-activated killer cells. Considering that tumor cell vaccines are aimed at inducing tumor-specific immune responses, our in vitro observation would rather argue against the in vivo application of such a tumor cell modification in colorectal cancer.
Journal of Molecular Medicine 02/1996; 74(1):43-9. · 4.67 Impact Factor
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ABSTRACT: The bacterial enzyme cytosine deaminase (CD) catalyzes the conversion of 5-fluorocytosine (5-FC) to the lethal 5-fluorouracil (5-FU) and so provides a useful system for selective killing of gene-modified mammalian tumor cells. Cloning of the CD gene from Escherichia coli and expression in human tumor cell lines enabled these cells to convert 3H-labeled 5-FC into 3H-5-FU. Two CD-expressing human tumor cell lines (adenocarcinoma cell line KM12 and glioblastoma cell line T1115) became 200-fold more sensitive to 5-FC than the nonexpressing parental cell lines. At least 90% of the cells are killed within 7 days. CD-expressing cells are able to kill nonexpressing cells when grown in the same culture flask (bystander effect). The CD gene may be used as a suicide system for in situ chemotherapy or as a safety mechanism abrogating the expression of other genes.
Journal of Surgical Oncology 02/1996; 61(1):42-8. · 2.10 Impact Factor
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ABSTRACT: Genetically modified mammalian cells that express the cytosine deaminase (CD) gene are able to convert the nontoxic prodrug 5-fluorocytosine (5-FC) to the toxic metabolite 5-fluorouracil (5-FU). PET with 18F-5-FC may be used for in vivo measurement of CD activity in genetically modified tumors.
A human glioblastoma cell line was stably transfected with the Escherichia coli CD gene. After incubation of lysates of CD-expressing cells and control cells with 3H-5-FC high-performance liquid chromatography (HPLC) was performed. The uptake of 5-FC was measured after various incubation times using therapeutic amounts of 5-FC. In addition, saturation and competition experiments with 5-FC and 5-FU were performed. Finally, the efflux was measured.
We found that 3H-5-FU was produced in CD-expressing cells, whereas in the control cells only 3H-5-FC was detected. Moreover, significant amounts of 5-FU were found in the medium of cultured cells, which may account for the bystander effect observed in previous experiments. However, uptake studies revealed a moderate and nonsaturable accumulation of radioactivity in the tumor cells, suggesting that 5-FC enters the cells only through diffusion. Although a significant difference in 5-FC uptake was seen between CD-positive and control cells after 48 hr of incubation, no difference was observed after 2 hr of incubation. Furthermore, a rapid efflux could be demonstrated.
5-Fluorocytosine transport may be a limiting factor for this therapeutic procedure. Quantitation with PET has to rely more on dynamic studies and modeling, including HPLC analysis of the plasma, than on nonmodeling approaches.
Journal of Nuclear Medicine 02/1996; 37(1):87-94. · 6.38 Impact Factor
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ABSTRACT: The capacity of colorectal carcinoma and melanoma cell lines to induce primary versus effector T lymphocyte activation in vitro was investigated. Established epithelial tumour cell lines derived from colorectal carcinoma and melanoma did not activate a primary proliferative response of resting T lymphocytes in allogeneic mixed lymphocyte tumour cell cultures (MLTCs). In contrast, the same tumour cells were effectively lysed by preactivated cytolytic T cell clones. This demonstrates that tumour cells are impaired in inducing a primary immune response but are susceptible to effector immune responses. Attempts at improving primary T cell activation revealed that exogenous cytokines, including interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2), were not effective. Expression of CD80 (B7.1), by transfecting a CD80 cDNA into the melanoma cell line SkMel63, improved T cell proliferation considerably. In contrast, CD80 expression in two colorectal carcinoma cell lines (SW480, SW707) did not result in T cell activation. This was not due to lack of class II MHC expression on SW480 since coexpression of a HLA-DR3 alloantigen and CD80 had no effect. Our data suggest that de novo CD80 expression is not, in general, sufficient to improve primary T cell activation by human tumour cells.
European Journal of Cancer 01/1996; 31A(13-14):2396-402. · 5.54 Impact Factor
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ABSTRACT: Human tumor cell lines derived from breast and ovarian carcinomas have been found to be ineffective in stimulating the induction phase of an immune response such as T cell proliferation in allogeneic mixed tumor cell lymphocyte cultures. Since representative tumor cell lines are effectively lysed by activated T lymphocytes, the induction of an effector phase is not impaired. In order to reconstitute the potential to induce primary T cell activation, we transfected CD80 into a breast (KS) and an ovarian carcinoma (GG) cell line. CD80 expression in KS cells resulted in improved primary T cell activation, whereas it was ineffective in the case of GG cells. However, treatment of CD80-transfected GG cells with INF-gamma rendered them immunogenic, and resulted in T cell proliferation. Likewise, TNF-alpha and/or INF-gamma augmented T cell proliferation induced by CD80-transfected KS cells. Furthermore, T lymphocytes stimulated with cytokine-treated CD80+ KS cells gave rise to a long term proliferating CD8+ CTL line with class I MHC restricted cytolytic antitumor activity. These studies emphasize the requirement for costimulation in generating tumor-specific immunity, and demonstrate the efficacy of CD80 in generating CD8+ cytolytic T lymphocytes.
Cytokines and molecular therapy 10/1995; 1(3):211-21.
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ABSTRACT: The hepatic zonation of peroxisomes and four of their matrical enzyme proteins (catalase, acyl coenzyme A oxidase, multifunctional protein, thiolase) has been investigated in normal male rats and after treatment with three divergent hypolipidemic drugs by means of automatic image analysis and quantitative immunoelectron microscopy. The induction of peroxisomal enzymes was confirmed by Western blotting and enzyme activity determinations in liver homogenates and in highly purified peroxisome fractions. In control animals the volume density of peroxisomes and the concentrations of all four enzymes were comparable across the liver acinus. The treatment with all three compounds induced stronger proliferation of peroxisomes in zone 3 than in zone 1 hepatocytes, and significant differences between the different compounds were detectable only in pericentral hepatocytes. The immunolabeling density reflecting the enzyme protein concentration in the peroxisomal matrix was unchanged or reduced for catalase but showed significant elevations for beta-oxidation enzymes in treated animals. It did not increase, however, in parallel with the augmentation of the volume density but showed a different pattern for each enzyme, depending on the acinar location and the type of compound used, suggesting a complex fine regulation for each protein. The total labeling index, reflecting the total amount of each protein, was for almost all enzymes higher in perivenous hepatocytes, indicating that they respond more intensely to hypolipidemic drugs than periportal cells. The elevations of the peroxisomal enzymes in zone 3 of the acinus may contribute to the perturbation of the sterol and bile acid metabolism associated with hypolipidemic therapy.
Hepatology 09/1994; 20(2):475-86. · 11.66 Impact Factor
