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Biomedical subjects

Thomas G Berger

Publications and source records attributed to Thomas G Berger.

12 recordsLinked to original sources
PubMed2005

Differences in phenotype and function between spontaneously occurring melan-A-, tyrosinase- and influenza matrix peptide-specific CTL in HLA-A*0201 melanoma patients.

Melanoma-specific T cells can occur spontaneously or in response to vaccination or other therapies, but the frequency is much lower than observed in viral infections. The presence of tumor-specific T cells does not necessarily translate into clinical regressions for a variety of reasons such as an insufficient frequency, activation state or homing capacity of the T cells or escape strategies of the tumor. Having screened melanoma patients prior to inclusion in vaccination trials for spontaneous tumor-specific T cells either by Elispot or tetramer-staining, we have identified 3 patients with sufficient numbers of tumor-reactive T cells to more than 1 TAA and at least 1 virus-antigen to perform phenotypic and functional analysis directly ex vivo. These stage IV melanoma patients showed specific CTL against melan-A.A2, tyrosinase.A2 and influenza matrix peptide (IMP).A2 readily detectable in peripheral blood. T-cell receptor (TCR) staining using the tetramer technology was combined with phenotypic characterization and functional assays. In contrast to IMP-specific CTL, melanoma-specific CTL were predominantly terminally differentiated effector cells. However, analysis of melan-A- and tyrosinase-specific T-cell lines showed that only a part of the melanoma-specific CTL were able to lyse peptide-loaded target cells. Interestingly, the described phenotypic and functional differences of melan-A- and tyrosinase-specific CTL appeared not only between patients but were also evident within patients, suggesting that the immune response against various tumor antigens is regulated independently.

Adult↗
PubMed2005

Efficient elutriation of monocytes within a closed system (Elutra) for clinical-scale generation of dendritic cells.

Dendritic cells (DC) are promising tools for the immunotherapy of cancer. The induction of tumor-specific T cells and clinical regressions have already been observed in early phase I/II vaccination trials. As DC vaccination is now facing trials with larger patient collectives it becomes increasingly important to obtain large numbers of cells suitable for therapeutic applications under labor- and cost-effective conditions. We describe here a procedure that uses a novel cell separator (Elutra, Gambro BCT) to enrich monocytes from an entire apheresis product within one hour. Cells are separated on the basis of size and to a lesser extent density, by elutriation in a 40-ml conical chamber. The total monocyte recovery following elutriation (n = 6) was 98.53% (+/-8.07%), the recovery in the monocyte-rich fraction 75.45% (+/-11.31%), and the mean purity 82.95% (+/-6.01%). These monocytes can be cultured either in conventional culture dishes or in closed cell culture bags and differentiated, by using GM-CSF+IL-4 followed by a maturation cocktail composed of IL-1beta+IL-6+TNF-alpha+PGE2, into fully mature DC. The Elutra separator allows for fast and easy enrichment of monocytes within a closed system. Subsequently, elutriated monocytes can be successfully cultured into phenotypically and functionally mature DC for immunotherapeutic approaches. The method neither requires a density gradient step to enrich PBMC from leucapheresis products nor does it apply (xenogeneic) antibodies to target monocytes. Isolation of monocytes with Elutra may greatly facilitate future DC-based vaccination approaches.

Cell Differentiation↗
PubMed2005

Artesunate in the treatment of metastatic uveal melanoma--first experiences.

Artesunate (ART) is a derivative of artemisinin, the active principle of the Chinese herb Artemisia annua L. Artesunate is approved for the treatment of multidrug-resistant malaria and has an excellent safety profile. It has been shown that Artesunate, apart from its anti-malarial activity, has cytotoxic effects on a number of human cancer cell lines, including leukemia, colon cancer and melanoma. We report on the first long-term treatment of two cancer patients with ART in combination with standard chemotherapy. These patients with metastatic uveal melanoma were treated on a compassionate-use basis, after standard chemotherapy alone was ineffective in stopping tumor growth. The therapy-regimen was well tolerated with no additional side effects other than those caused by standard chemotherapy alone. One patient experienced a temporary response after the addition of ART to Fotemustine while the disease was progressing under therapy with Fotemustine alone. The second patient first experienced a stabilization of the disease after the addition of ART to Dacarbazine, followed by objective regressions of splenic and lung metastases. This patient is still alive 47 months after first diagnosis of stage IV uveal melanoma, a situation with a median survival of 2-5 months. Despite the small number of treated patients, ART might be a promising adjuvant drug for the treatment of melanoma and possibly other tumors in combination with standard chemotherapy. Its good tolerability and lack of serious side effects will facilitate prospective randomized trials in the near future.

Aged↗
PubMed2004

Circulation and homing of melanoma-reactive T cells to both cutaneous and visceral metastases after vaccination with monocyte-derived dendritic cells.

Anticancer immune therapies aim at the induction of tumor-specific T cells, which ultimately should kill tumor cells. The effector cells should, therefore, not only exert cytotoxic activity but also home to and infiltrate the tumor site. Hence, monitoring of immune modulating therapies should not be restricted to the circulating pool of peripheral blood mononuclear cells (PBMC) but also include tumor-infiltrating lymphocytes (TIL), as well as the correlation of these findings to the clinical course. We report here on the longitudinal immunologic workup of a melanoma patient who developed remarkably potent ex vivo detectable antimelanoma cytotoxic T-cell (CTL) responses after vaccinations with autologous peptide-pulsed dendritic cells. Such potent CTL responses to multiple tumor antigens have, to the best of our knowledge, not been described previously in melanoma patients, neither spontaneously nor after any therapy. This patient first experienced a transient response to therapy but finally succumbed to disease progression and died. Progression was associated with the decline of the numbers of tumor-reactive T cells in circulation and at skin metastases in addition to the loss of MHC class I antigens. The immunologic analysis revealed that fully functional tumor-specific T cells were present in the peripheral blood of this patient during the phase of a relatively stable disease, and in situ tetramer staining demonstrated that these cells were also accumulated at cutaneous and visceral tumor sites. Furthermore, comparative clonotype mapping of PBMC and TIL depicted an overlapping TCR repertoire usage among these 2 compartments. Since strong CTL responses as observed in this patient are the goal of cancer vaccination but are so far only rarely observed, the thorough analysis of patients exhibiting either exceptional clinical and/or immunologic responses appears critical to understanding how vaccine therapies work and can be further improved.

Aged↗
PubMed2004

Immunogenicity of constitutively active V599EBRaf.

Activating BRAF somatic missense mutations within the kinase domain are present in 60-66% of melanomas. The vast majority of these represent a single substitution of glutamate for valine (V599E). Here, we demonstrate spontaneous HLA-B*2705-restricted cytotoxic T-cell responses against an epitope derived from (V599E)BRaf. These T-cell responses were mutation specific as the corresponding epitope derived from wild-type BRaf was not recognized. The loss of the (V599E)BRAF genotype during progression from primary to metastatic melanoma in patients with (V599E)BRaf specific T-cell responses suggests an active immune selection of nonmutated melanoma clones by the tumor-bearing host.

Disease Progression↗
PubMed2004

Functional analysis of tumor-specific Th cell responses detected in melanoma patients after dendritic cell-based immunotherapy.

Recently, we have demonstrated that tumor-specific CD4+ Th cell responses can be rapidly induced in advanced melanoma patients by vaccination with peptide-loaded monocyte-derived dendritic cells. Most patients showed a T cell reactivity against a melanoma Ag 3 (MAGE-3) peptide (MAGE-3(243-258)), which has been previously found to be presented by HLA-DP4 molecules. To analyze the functional and specificity profile of this in vivo T cell response in detail, peptide-specific CD4+ T cell clones were established from postvaccination blood samples of two HLA-DP4 patients. These T cell clones recognized not only peptide-loaded stimulator cells but also dendritic cells loaded with a recombinant MAGE-3 protein, demonstrating that these T cells were directed against a naturally processed MAGE-3 epitope. The isolated CD4+ Th cells showed a typical Th1 cytokine profile upon stimulation. From the first patient several CD4+ T cell clones recognizing the antigenic peptide used for vaccination in the context of HLA-DP4 were obtained, whereas we have isolated from the second patient CD4+ T cell clones which were restricted by HLA-DQB1*0604. Analyzing a panel of truncated peptides revealed that the CD4+ T cell clones recognized different core epitopes within the original peptide used for vaccination. Importantly, a DP4-restricted T cell clone was stimulated by dendritic cells loaded with apoptotic or necrotic tumor cells and even directly recognized HLA class II- and MAGE-3-expressing tumor cells. Moreover, these T cells exhibited cytolytic activity involving Fas-Fas ligand interactions. These findings support that vaccination-induced CD4+ Th cells might play an important functional role in antitumor immunity.

Amino Acid Sequence↗
PubMed2004

Blastic CD56+ natural killer-cell lymphoma with primary cutaneous manifestation.

T/natural killer-cell lymphomas belong to a heterogeneous group of non-Hodgkin lymphomas with predominant extranodal, often cutaneous, manifestations. In contrast to B- and T-cell lymphomas, T/NK-cell lymphomas were only recently regarded as a distinct entity. These rather aggressive malignancies arise from cytotoxic T cells, NK-cells or NK-like T cells, which share several phenotypic and functional properties. We report a man with a blastic NK-cell lymphoma with nodular skin infiltrations as the leading clinical manifestation of the disease. Complicated of tuberculosis, the patient died within 9 months of diagnosis, despite aggressive polychemotherapy.

Aged↗
PubMed2003

Antigen loading of dendritic cells with whole tumor cell preparations.

Dendritic cells (DC) based vaccinations have been widely used for the induction of anti-tumoral immunity in clinical studies. Antigen loading of DC with whole tumor cell preparations is an attractive method whenever tumor cell material is available. In order to determine parameters for the loading procedure, we performed dose finding and timing experiments. We found that apoptotic and necrotic melanoma cells up to a ratio of one-to-one, equivalent to 1mg/ml protein per 1 x 10(6) DC, can be added to monocyte derived DC without effecting DC recovery extensively. Using the isolated protein content of tumor cells (lysate) as a parameter, up to 5 mg/ml protein per 1 x 10(6) DC can be added. To achieve significant protein uptake at least 1 mg/ml of protein have to be added for more than 24 h as tested with FITC-labelled ovalbumin. Maturation inducing cytokines can be added simultaneously with the tumor cell preparations to immature DC without affecting the uptake. Furthermore, we tested the feasibility of cryopreservation of loaded and matured DC to facilitate the generation of ready to use aliquots. DC were cryopreserved in a mix of human serum albumin, DMSO and 5% glucose. After thawing, surface expression of molecules indicating the mature status (CD83, costimulatory and MHC molecules), was found to be unaltered. Furthermore, cryopreserved DC kept the capability to stimulate allogenic T-cell proliferation in mixed leukocyte reactions at full level. Loaded and matured DC pulsed with influenza matrix peptide (IMP) retained the capacity to induce the generation of IMP-specific cytotoxic T-lymphocytes after cryopreservation as measured by ELISPOT and tetramer staining. The expression of the chemokine receptor CXCR-4 and CCR-7 remained unaltered during cryopreservation and the migratory responsiveness towards MIP-3beta was unaltered as measured in a migration assay. Thus we conclude that the large scale loading and maturation of DC with whole tumor cell preparations can be performed in a single session. These data will facilitate the clinical application of DC loaded with whole tumor cell preparations.

Antigens, CD↗
PubMed2003

Comparison of two apheresis systems for the collection of CD14+ cells intended to be used in dendritic cell culture.

BACKGROUND: Monocytes collected by leukapheresis are increasingly used for dendritic cell (DC) culture in cell factories suitable for DC vaccination in cancer. STUDY DESIGN AND METHODS: Using modified MNC programs on two apheresis systems (Cobe Spectra and Fresenius AS.TEC204), leukapheresis components collected from 84 patients with metastatic malignant melanoma and from 31 healthy male donors were investigated. MNCs, monocytes, RBCs, and platelets (PLTs) in donors and components were analyzed by cell counters, WBC differential counts, and flow cytometry. RESULTS: In 5-L collections, Astec showed better results regarding monocyte collection rates (11.0 vs. 7.4 x 10(6)/min, p = 0.04) and efficiencies (collection efficiency, 51.9 vs. 31.9%; p < 0.001). Both devices resulted in monocyte yields at an average of 1 x 10(9) (donors) and 2.5 x 10(9) (patients), whereas Astec components contained high residual RBCs. Compared to components with low residual PLTs, high PLT concentration resulted in higher monocyte loss (48 vs. 20%, p < 0.0001) before DC culture. CONCLUSION: The Astec is more efficient in 5-L MNC collections compared to the Spectra. Components with high residual PLTs result in high MNC loss by purification procedures. Thus, optimizing MNC programs is essential to obtain components with high MNC yields and low residual cells as prerequisite for high DC yields.

Adult↗
PubMed2002

Large-scale generation of mature monocyte-derived dendritic cells for clinical application in cell factories.

Dendritic cells (DC) are increasingly used for the immunotherapy of cancer. Both the induction of tumor-specific T cells and some clinical regressions have been observed in early phase I/II trials by using either DC isolated from blood, DC generated from CD34+ precursors ex vivo, and most frequently, by employing monocyte-derived DC. As DC vaccination is now awaiting phase II/III trials with larger patient collectives, it becomes increasingly important to overcome prior limitations such as the repetitive, labor-intensive generation of DC in a large number of open culture vessels. We describe here as a result of several years of optimization, in detail, a procedure that uses the so-called Nunc cell factories to process a whole apheresis product, labor- and cost-effectively in a quasi-closed system to reproducibly generate (by using GM-CSF+IL-4 followed by a maturation cocktail composed of IL-1beta+IL-6+TNF-alpha +PGE(2)) large numbers (8.32+/-3.8% of input peripheral blood mononuclear cells (PBMC)) of mature (>85% CD83+), monocyte-derived DC that can be successfully cryopreserved. Our report is based on the processing of >100 aphereses including 52 unselected aphereses in advanced melanoma patients. This allows us also to suggest meaningful quality and validation criteria. The DC generation method appears particularly promising as respective DC vaccination proved to be immunogenic in cancer patients and cell factories can readily be converted to a fully closed system by using appropriate valves, tubings, and bags.

Blood Component Removal↗
PubMed2002

Rapid induction of tumor-specific type 1 T helper cells in metastatic melanoma patients by vaccination with mature, cryopreserved, peptide-loaded monocyte-derived dendritic cells.

There is consensus that an optimized cancer vaccine will have to induce not only CD8+ cytotoxic but also CD4+ T helper (Th) cells, particularly interferon (IFN)-gamma-producing, type 1 Th cells. The induction of strong, ex vivo detectable type 1 Th cell responses has not been reported to date. We demonstrate now that the subcutaneous injection of cryopreserved, mature, antigen-loaded, monocyte-derived dendritic cells (DCs) rapidly induces unequivocal Th1 responses (ex vivo detectable IFN-gamma-producing effectors as well as proliferating precursors) both to the control antigen KLH and to major histocompatibility complex (MHC) class II-restricted tumor peptides (melanoma-antigen [Mage]-3.DP4 and Mage-3.DR13) in the majority of 16 evaluable patients with metastatic melanoma. These Th1 cells recognized not only peptides, but also DCs loaded with Mage-3 protein, and in case of Mage-3DP4-specific Th1 cells IFN-gamma was released even after direct recognition of viable, Mage-3-expressing HLA-DP4+ melanoma cells. The capacity of DCs to rapidly induce Th1 cells should be valuable to evaluate whether Th1 cells are instrumental in targeting human cancer and chronic infections.

Adult↗