Acute myeloid leukemia (AML) is a highly heterogeneous disorder that results from a block in the differentiation of hematopoietic progenitor cells along with uncontrolled proliferation. In approximately 60% of cases, specific recurrent chromosomal aberrations can be identified by modern cytogenetic techniques, and is an important indicator to classify patients into three prognostic categories: favorable, intermediate, and poor risk. Currently, favorable risk patients are usually treated with chemotherapy while poor risk patients receive allogeneic stem cell transplantation. However, the largest subgroup of AML patients (approximately 40%) has no identifiable cytogenetic abnormalities and is classified as intermediate risk. In this special subgroup of patients, a number of studies have demonstrated the relationship between different translocations involving the mixed lineage leukemia (MLL) gene and patient prognosis. The heterogeneity of MLL-rearranged AML is reflected by the identification of more than 70 different fusion partners of this gene and the panel is continuously increasing. The aim of this study is to develop a sensitive molecular profiling test for relevant risk stratification that can help in the decision of treatment and/or follow-up strategy.

Imatinib mesylate is indicated for the treatment of chronic myeloid leukemia (CML) and unresectable and/or metastatic malignant gastrointestinal stromal tumors (GIST). By the application of this anticancer drug, problems occurs in terms of stability and activity. Computer assisted design (CAD) works showed that the modification of the B and C part molecule can increase the effectivity of the drug. The new derivatives of the drug will be obtained to change some part of the B and C segments. The total synthesis of a new imatinib mesylate will be done and the activity tests are going to be determined in collaboration with other groups.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 85-105).

Gain- and loss-of-function studies of the BCL-2 family of proteins have shown that they can impact chemotherapeutic sensitivity. However, cells contain myriad anti-apoptotic and pro-apoptotic BCL-2 family members making it difficult to predict cell fate decisions based on the initial conditions of these proteins. BH3 profiling is a tool that measures mitochondrial priming, the readiness of a cell to die through the intrinsic (or mitochondrial) apoptotic pathway. Priming is due to the cumulative effect of the BCL-2 family of proteins that act as the gate keepers of the mitochondrial apoptotic pathway. Priming is measured by determining the sensitivity of mitochondria to perturbation by peptides derived from the BH3 domains of pro-apoptotic proteins. Using BH3 profiling, we now have a functional readout that can quantify priming and assess its contribution to drug sensitivity. Here we show that priming affects the sensitivity of acute myeloid leukemia (AML) cell lines to various standard chemotherapeutics, especially topoisomerase II inhibitors. Priming predicts clinical response to conventional induction chemotherapy as well as the long term maintenance of remission in AML patients. Interestingly, the priming of normal hematopoietic stem cells (HSCs) sits at the boundary line between the priming of cured and refractory patient AML. This HSC priming likely defines the therapeutic index since AML that are lower primed than HSCs are often refractory and cannot be cured without transplantation. Additionally, our BH3 profiles revealed that AML cells are more sensitive to BCL-2 antagonism than normal HSCs, which are primarily dependent on MCL-1. Indeed, we were able to kill primary refractory AML cells in vitro with the BCL-2 antagonist ABT-737 at doses that left HSCs unharmed. Cumulatively, these findings show that priming is a major mechanistic determinant of AML response in vitro and in the clinic to standard induction chemotherapy. With the ability to predict outcome, BH3 profiling may offer physicians and patients a promising tool for treatment decision-making.

Hematopoietic stem and progenitor cells proliferate and differentiate to reconstitute all lineages of functional blood cells. They are regulated by intricate cellular and molecular signals, on both genetic and epigenetic levels. Alterations in these regulatory signaling networks can lead to hematopoietic dysfunction, as well as transformation of hematopoietic cells and induction of leukemogenesis. This thesis focuses on uncovering molecular modulators that are crucial for the proper regulation of hematopoietic stem/progenitor cells. In Chapter II, I describe studies investigating functional roles of the histone demethylase UTX in normal and malignant hematopoiesis, using a short hairpin RNA-mediated knockdown approach. My data revealed that UTX is required for proliferation, self-renewal and differentiation of hematopoietic progenitor cells ex vivo through transcriptional regulation of hematopoiesis- specific transcriptional factors. I also discovered that UTX is critical for the proliferation of leukemia cells, implicating UTX as a possible target for clinical therapy. In Chapter III, I focus on understanding the process of leukemogenesis by generating and characterizing a novel model of myeloid sarcoma and acute myeloid leukemia in mice. This model induces these hematopoietic malignancies by introduction of multiple oncogenetic lesions (specifically, p16/p19-/-;Kras(G12V)) into bone marrow cells, and subsequent transplantation of these gene-modified cells into immunodeficient NOD.SCID mice. This model is very rapid and reproducible, and represents the first transplantable myeloid sarcoma model reported. Moreover, the disease induced in mice recapitulates the pathological progression of myeloid sarcoma in patients, providing a powerful model for dissection of critical leukemogenic events and discovery of new candidate therapeutic targets. Together, these studies help to reveal novel molecular modulators required for normal hematopoiesis, and offer potential animal model and drug target for therapeutic applications.

Voriconazole is a broad spectrum antifungal agent. Patients with acute myeloid leukemia that are susceptible to fungal infections receive simultaneously voriconazole and antitumor regimens. Drug-drug interactions between voriconazole and cytarabine involving the CYP3A4 enzyme are thought to affect the pharmacokinetic profile of the drugs and as a result their toxicological or pharmacological outcome. Population pharmacokinetic models were used to characterize these interactions and optimize the dose schemes after coadministration. Simulations and estimations were conducted by using NONMEM. The optimal dose for one hour intravenous infusion of voriconazole was estimated to 5mg/h. The proposed time points based on the pharmacokinetic profile of voriconazole for validated the model by using a small cohort of patients are 2h, 26h, 27h, 50h, 51h, 120h, 335h, 336h after the first administration of the antifungal agent. / Η βορικοναζόλη αποτελεί έναν ευρέως φάσματος αντιμυκητιασικό παράγοντα. Ασθενείς με οξεία μυελογενή λευχαιμία (ΟΜΛ) που θεωρούνται ευπαθείς στην ανάπτυξη μυκητιάσεων λαμβάνουν βορικοναζόλη σε συγχορήγηση με τα αντικαρκινικά φάρμακα. Αλληλεπιδράσεις φαρμάκων που λαμβάνουν χώρα κατά την διάρκεια του μεταβολισμού των χρησιμοποιούμενων φαρμάκων από κοινά ισοένζυμα του κυττοχρώματος P450 πιθανότατα να επιρεάζουν το φαρμακοκινητικό προφίλ τών φαρμάκων. Πληθυσμιακά φαρμακοκινητικά μοντέλα χρησιμοποιήθηκαν για τον χαρακτηρισμό αυτών των αλληλεπιδράσεων και την βελτιστοποίηση του δοσολογικού σχήματος. Προσομοιώσεις και υπολογισμοί πραγματοποιήθηκαν μέσω του προγράμματος NONMEM. Η βέλτιστη δόση μετά μια ώρα έγχυσης της βορικοναζόλης είναι 5mg/L. Τα προτεινόμενα χρονικά σημεία βασισμένα στο φαρμακοκινητικό προφίλ της βορικοναζόλης για την διεξάγωγή μικρού μήκους κλινικής μελέτης που θα επιτρέψει την αξιολόγηση του μοντέλου είναι 2h, 26h, 27h, 50h, 51h, 120h, 335h, 336h μετά την χορήγηση του αντιμυκητιασικού φαρμάκου.

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Monocyte recruitment promotes the accumulation of myeloid foam cells in early atherosclerotic plaques. However, initial foam cells form prior to increased monocyte recruitment in hypercholesterolemic Ldlr-/- mice. These initial foam cells are derived from myeloid cells residing in the normal intima, and express integrin alphaX (CD11c). The goal of this thesis was to assess the role of initial foam cells in atherogenesis. The approach was to delete these cells by diphtheria toxin-induced apoptosis in Ldlr-/- bone marrow chimeras. Depletion of CD11c+ leukocytes resulted in significant reductions of intimal lipid accumulation, monocyte recruitment, intimal chemokine expression, but not endothelial cell adhesion molecule expression, at 10 and 21 days of hypercholesterolemia. These data suggest that lipid uptake by resident intimal CD11c-expressing myeloid cells during the earliest stages of atherosclerosis promotes chemokine production that is required for increased monocyte recruitment.

Monocyte recruitment promotes the accumulation of myeloid foam cells in early atherosclerotic plaques. However, initial foam cells form prior to increased monocyte recruitment in hypercholesterolemic Ldlr-/- mice. These initial foam cells are derived from myeloid cells residing in the normal intima, and express integrin alphaX (CD11c). The goal of this thesis was to assess the role of initial foam cells in atherogenesis. The approach was to delete these cells by diphtheria toxin-induced apoptosis in Ldlr-/- bone marrow chimeras. Depletion of CD11c+ leukocytes resulted in significant reductions of intimal lipid accumulation, monocyte recruitment, intimal chemokine expression, but not endothelial cell adhesion molecule expression, at 10 and 21 days of hypercholesterolemia. These data suggest that lipid uptake by resident intimal CD11c-expressing myeloid cells during the earliest stages of atherosclerosis promotes chemokine production that is required for increased monocyte recruitment.

The value of the combination of gemtuzumab ozogamicin (GO) and chemotherapy for the treatment of acute myeloid leukemia (AML) is currently analyzed within clinical trials. GO (6 mg/m2) and standard-dose cytarabine (100 mg/m2) is evaluated for the treatment of newly diagnosed AML in elderly patients in the SAL phase II trial. Preliminary results of the MRC AML15 trial support the application of GO 3 mg/m2 with standard- and high-dose cytarabine and anthracyclines for the treatment of de novo AML. Within this trial the addition of GO seems especially of value for favorable and intermediate cytogenetic risk groups. The combination of GO (3 mg/m2) and high-dose cytarabine (3 g/m2) is safe and more effective for the treatment of refractory AML than previous combinations from the AMLSG study group. First results prove the possibility of allogeneic stem cell transplantation after GO therapy. Initial data of a phase II trial document the safety and efficacy profile of GO within a reduced-intensity conditioning protocol applying fludarabine and total body irradiation. / Der Stellenwert von Gemtuzumab Ozogamicin (GO) in der Kombination mit Chemotherapie für die Behandlung der akuten myeloischen Leukämie (AML) wird derzeit auch in Europa untersucht. Der Einsatz von GO (6 mg/m2) in Kombination mit Cytarabin (100 mg/m2) bei der Primärbehandlung älterer Patienten mit AML wird in der SAL-Phase-II-Studie geprüft. Das in der MRC-AML15-Studie nachgewiesene verbesserte krankheitsfreie Überleben belegt den Stellenwert von GO (3 mg/m2) in Kombination mit Standard- und hoch dosiertem Cytarabin und einem Anthrazyklin für die Induktion und Konsolidierung bei neu diagnostizierter AML. Insbesondere Patienten mit einem günstigen und intermediären zytogenetischen Risikoprofil scheinen von der Gabe von GO zu profitieren. In der Behandlung von AML-Rezidiven oder refraktärer Erkrankung erwies sich GO (3 mg/m2) als sicher mit hoch dosiertem Cytarabin (3 g/m2) kombinierbar und war in der Wirksamkeit historischen Vergleichskollektiven der AMLSG-Studiengruppe überlegen. Erste Ergebnisse dokumentieren die Möglichkeit einer allogenen Stammzelltransplantation nach GO-Therapie. Erste Daten einer laufenden Studie belegen auch die Einsatzmöglichkeit und das Sicherheitsprofil von GO als Bestandteil einer Konditionierungstherapie von reduzierter Intensität mit Fludarabin und Ganzkörperbestrahlung. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.