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  • 1
    Abstract: Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous disease with poor outcome. Adequate model systems are required for preclinical studies to improve understanding of AML biology and to develop novel, rational treatment approaches. Xenografts in immunodeficient mice allow performing functional studies on patient-derived AML cells. We have established an improved model system that integrates serial retransplantation of patient-derived xenograft (PDX) cells in mice, genetic manipulation by lentiviral transduction, and essential quality controls by immunophenotyping and targeted resequencing of driver genes. 17/29 samples showed primary engraftment, 10/17 samples could be retransplanted and some of them allowed virtually indefinite serial transplantation. 5/6 samples were successfully transduced using lentiviruses. Neither serial transplantation nor genetic engineering markedly altered sample characteristics analyzed. Transgene expression was stable in PDX AML cells. Example given, recombinant luciferase enabled bioluminescence in vivo imaging and highly sensitive and reliable disease monitoring; imaging visualized minimal disease at 1 PDX cell in 10000 mouse bone marrow cells and facilitated quantifying leukemia initiating cells. We conclude that serial expansion, genetic engineering and imaging represent valuable tools to improve the individualized xenograft mouse model of AML. Prospectively, these advancements enable repetitive, clinically relevant studies on AML biology and preclinical treatment trials on genetically defined and heterogeneous subgroups.
    Type of Publication: Journal article published
    PubMed ID: 25793878
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  • 2
    Keywords: brain ; APOPTOSIS ; CANCER ; CELLS ; IN-VITRO ; SURVIVAL ; AGENTS ; CELL ; Germany ; IN-VIVO ; VITRO ; DEATH ; DRUG ; SURGERY ; LINES ; TIME ; PATIENT ; LIGAND ; primary ; INDUCTION ; tumour ; treatment ; culture ; ACID ; CELL-DEATH ; PLASMA ; RATES ; RESECTION ; PHARMACOKINETICS ; CISPLATIN ; FUTURE ; TRAIL ; AGENT ; POTENT ; REGRESSION ; IV ; GRADE ; brain tumour ; betulinic acid ; CERAMIDE ; glioblastoma multiforme WHOIV
    Abstract: Background. Glioblastoma multiforme (WHO Grade IV, GBM) is the most malignant brain tumour with a mean survival time of less than one year. Betulinic acid, ceramide and TRAIL (TNF-related apoptosis inducing ligand) represent novel therapeutic agents for potential use in GBM. Method. Primary GBM cells of 21 patients with macroscopically complete tumour resection were tested in vitro for cell death induction by betulinic acid, ceramide, TRAIL and established therapeutics (BCNU, cisplatin, doxorubicin, vincristin and gamma-irradiation). Findings. At peak plasma concentrations (PPC), Betulinic acid, ceramide and TRAIL induced cell death in primary GBM cells at higher rates than established cytotoxic drugs. Specific cell death greater than or equal to75% was observed in 43% (9/21), 38% (8/21), and 19% (4/21) for betulinic acid, ceramide, and TRAIL respectively, while this was only found in 5% (1/21) of gamma-irradiated and cisplatin-treated cells, and in none of the GBM cultures, where BCNU or vincristin were applied in PPC. Conclusion. Due to a markedly improved cell death of GBM cells as compared with established therapeutics, Betulinic acid, ceramide and TRAIL might represent potent substances for future treatment of GBM
    Type of Publication: Journal article published
    PubMed ID: 15197616
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  • 3
    Abstract: BACKGROUND AND PURPOSE: In polychemotherapy protocols, that is for treatment of neuroblastoma and Ewing sarcoma, Vinca alkaloids and cell cycle-arresting drugs are usually administered on the same day. Here we studied whether this combination enables the optimal antitumour effects of Vinca alkaloids to be manifested. EXPERIMENTAL APPROACH: Vinca alkaloids were tested in a preclinical mouse model in vivo and in vitro in combination with cell cycle-arresting drugs. Signalling pathways were characterized using RNA interference. KEY RESULTS: In vitro, knockdown of cyclins significantly inhibited vincristine-induced cell death indicating, in accordance with previous findings, Vinca alkaloids require active cell cycling and M-phase transition for induction of cell death. In contrast, anthracyclines, irradiation and dexamethasone arrested the cell cycle and acted like cytostatic drugs. The combination of Vinca alkaloids with cytostatic therapeutics resulted in diminished cell death in 31 of 36 (86%) tumour cell lines. In a preclinical tumour model, anthracyclines significantly inhibited the antitumour effect of Vinca alkaloids in vivo. Antitumour effects of Vinca alkaloids in the presence of cytostatic drugs were restored by caffeine, which maintained active cell cycling, or by knockdown of p53, which prevented drug-induced cell cycle arrest. Therapeutically most important, optimal antitumour effects were obtained in vivo upon separating the application of Vinca alkaloids from cytostatic therapeutics. CONCLUSION AND IMPLICATIONS: Clinical trials are required to prove whether Vinca alkaloids act more efficiently in cancer patients if they are applied uncoupled from cytostatic therapies. On a conceptual level, our data suggest the implementation of polychemotherapy protocols based on molecular mechanisms of drug-drug interactions. LINKED ARTICLE: This article is commented on by Solary, pp 1555-1557 of this issue. To view this commentary visit
    Type of Publication: Journal article published
    PubMed ID: 23186127
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