Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic stem cell disorders with ineffective hematopoiesis. It is characterized by morphological dysplasia, peripheral cytopenias affecting one or more cell lineages and an increased risk of transformation into acute myeloid leukemia (AML). The early stages of MDS can be considered a premalignant disease. The pathogenesis of MDS has not been fully explained yet, but due to the development of molecular genetic and cytogenetic methods, the origin and development of the disease is gradually being elucidated. In addition to the cytogenetic changes that are part of the prognostic system (IPSS-R), the somatic mutations found in different genes come to the forefront of interest. However, they are not routinely used in clinical practice. One of the objectives of this study was monitoring of mutations in TP53 gene in lower-risk MDS patients who generally have a good prognosis and for whom these findings have a particularly relevant prognostic significance. We investigated a total of 154 patients with lower-risk MDS, and 13% of them had a mutation. After dividing patients according to the presence of del(5q), we observed significant differences in the incidence of the mutations. The mutations were detected in 23.6% of patients with...

Hematopoiesis has been for many years seen as a straightforward process based on sequential restriction of cell fate potential leading to production of mature blood cells. In the last decade, however, several works documented an unexpected plasticity of hematopoietic cells with expanded potential of myeloid development from lymphoid progenitors and vice versa. Under physiologic conditions hematopoiesis is tightly controlled and the definite cell fate is denominated by multiple factors that all lead to changes in regulatory networks that include transcription factors, epigenetic changes and post-transcriptional modulations. Any disruption of this strict regulation, caused by mutations or other events, affects the proliferation and lineage fidelity of hematopoietic precursors. This may lead to clonal growth of variable significance or leukemogenesis and may possibly affect the treatment sensitivity of the hematological malignancies. For better understanding of hematopoietic regulation we described gene expression changes during physiological development of lymphoid and myeloid lineages and in leukemic specimens using our own simplified real-time PCR based platform. We investigated expression of 95 genes connected with lymphoid and myeloid differentiation or with leukemogenesis in sorted hematopoietic...

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The overall aim of this thesis is to improve knowledge about the prevention of infectious and bleeding complications in patients with hematological malignancies, primarily in those with chronic lymphocytic leukemia (CLL) and myelodysplatic syndrome (MDS). Hypogammaglobulinemia, impaired production of immunoglobulins (Ig), is an established risk factor for infection, but the impact of IgG pure subclass deficiency (IgG subclass deficiency with adequate production of IgG, IgA, and IgM) has been debated. In a retrospective single institution study, we concluded that pure IgG subclass deficiency in CLL patients is rare and is not associated with an increased risk of infection. Hence, routine analysis of IgG subclasses in patients with CLL is not warranted. There is no consensus on recommending vaccination against Streptococcus pneumoniae to CLL patients mainly because comparative studies are lacking. In our randomized trial, the efficacy of a conjugated pneumococcal vaccine on immune response was superior or equal to a polysaccharide vaccine for all pneumococcal serotypes common for the two vaccines. A conjugate pneumococcal vaccine should therefore be included in vaccination programs for patients with CLL. Bronchoalveolar lavage (BAL) is a well-established invasive method to identify the cause of pulmonary infiltrates in immunocompromised patients. In a retrospective trial, we have studied the diagnostic yield of BAL in patients with hematological malignancies. We concluded that BAL is highly useful in either verifying or excluding some of the important respiratory tract infections affecting these patients, particularly invasive pulmonary aspergillosis (IPA) and Pneumocystis jirovecii pneumonia (PJP). However, standardized procedures for BAL sampling should be continually revised to avoid unnecessary microbiological tests. Thrombocytopenia, an adverse prognostic factor in patients with MDS, can be aggravated by azacitidine, first-line treatment for high-risk MDS. Eltrombopag, a thrombopoietin-receptor agonist (TPO-R), alleviates thrombocytopenia in patients with immune thrombocytopenic purpura (ITP). In a phase I clinical trial, we concluded that the combination of eltrombopag and azacitidine in high-risk MDS patients with thrombocytopenia is feasible and well tolerated in doses up to 200 mg eltrombopag daily.

Anemia aplástica adquirida (AAA) é doença rara e seu diagnóstico diferencial inclui a Síndrome mielodisplásica hipocelular (SMD-h). A evolução de AAA para SMD/LMA (Síndrome mielodisplásica/Leucemia mieloide aguda) ocorre em até 15% dos casos. Este estudo propõe-se a comparar parâmetros histológicos e imuno-histoquímicos de pacientes adultos e crianças com AAA que evoluíram e não para SMD/LMA. Seu objetivo é avaliar a ocorrência dos critérios morfológicos/imunofenotípicos nas biópsias de medula óssea do grupo pediátrico (<19 anos) com o grupo de adultos, comparar esses critérios associados à evolução para SMD/LMA nestes dois grupos e verificar se estes critérios superpõem-se àqueles descritos na literatura na SMD-hipocelular do adulto e, mais recentemente, na SMD pediátrica (Citopenia refratária da infância - CRI). Espera-se trazer uma contribuição para a discussão da intersecção entre essas entidades e a AAA, estudando essa \"zona cinzenta\" do ponto de vista dos pacientes com AAA, particularmente aqueles que progrediram para SMD/LMA. Foram analisadas, retrospectivamente, 118 biópsias de medula óssea ao diagnóstico de AAA, idiopática ou não, realizadas no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo entre 1993 e 2012. O diagnóstico de AAA foi estabelecido de acordo com critérios clássicos. A evolução de AAA para SMD ou LMA foi considerada na presença de: disgranulopoese ou dismegacariopoese acentuadas, mais de 15% de sideroblastos em anel, blastos em sangue periférico ou mais de 5% de blastos na medula óssea ao mielograma e/ou à biópsia de medula óssea ou na presença de estudo citogenético (FISH ou cariótipo) da medula óssea, apresentando monossomia ou deleção do braço longo do cromossomo 7. Todas as biópsias foram submetidas à análise morfológica e imuno-histoquímica (MPO, Glicoforina A, Fator VIII, CD34, CD117 e Ki-67) por dois hematopatologistas sem conhecimento prévio da evolução dos pacientes. As variáveis qualitativas nominais foram analisadas pelo teste exato de Fisher para verificar se houve desproporção significativa entre os grupos. As variáveis qualitativas ordinais foram analisadas para a diferença entre os grupos pelo teste de Mann-Whitney. O nível de significância adotado foi 5% (p=0,05). A correlação entre os valores de celularidade geral das amostras e seu índice proliferativo foi avaliada pelo teste não paramétrico Rô de Spearman. Setenta e um pacientes (60,2%) eram do gênero masculino com mediana de idade 24,4 anos (mínimo de 7 meses até 76 anos), 42 do grupo pediátrico e 76 adultos, e tempo de seguimento de 5,1 anos (de 1 mês a 22,1 anos). Doze (10,2%) (seis em cada grupo) pacientes evoluíram para SMD/LMA. Avaliação dos parâmetros morfológicos e imuno-histoquímicos mostrou distribuição irregular do tecido hematopoético em 59 (50%) casos, mediana de celularidade geral de 10% (de 1% a 40%), distúrbio de maturação da série granulocítica (critério 1) em três (2,5%) casos, localização anormal da eritropoiese em 13 (11%) casos, agregados de pelo menos 20 precursores eritroides (critério 2), em 54 (45,7%) casos, presença de formas jovens eritroides (proeritroblastos) (critério 3) em 32 (27,1%) casos, aumento do número de mitoses dos elementos eritroides (critério 4) em 24 (20,3%) casos, displasia de megacariócitos (micromegacariócitos, megacariócitos bi ou multinucleados e elementos hipo ou monolobados) (critério 5) em 15 (12,7%) casos, localização anormal de megacariócitos em quatro (3,3%) casos, megacariócitos CD34-positivos não foram identificados, blastos CD34-positivos em 11 (9,3%) casos, reticulogênese discretamente aumentada (grau 1) em três (2,5%) casos e índice proliferativo (Ki-67) com mediana de 30 (de 0% a 90%). Critérios descritos por Bennett e Orazi sugestivos de SMD-h (critérios 1 e/ou 5) foram detectados em 16 (13,6%) casos. Critérios descritos por Baumann et al. sugestivos de SMD da infância (critérios 2 + 3 com ou sem 4) foram observados em 30 (25,4%) casos. Não houve diferença estatística nos achados morfológicos/imuno-histoquímicos entre a população total, adultos e crianças que evoluíram e que não evoluíram para SMD/LMA, incluindo a presença de critérios Bennett e Orazi para SMD-h do adulto. Houve diferença quanto aos critérios de Baumann et al. para CRI, e o grupo que não evoluiu para SMD/LMA apresentou com mais frequência os critérios do que o que evoluiu (p=0,036), ao contrário do previamente suposto. No entanto, ao testar esta hipótese no grupo adulto separado do pediátrico, a diferença estatística não foi comprovada. Houve uma correlação estatisticamente significante entre os valores da celularidade geral das amostras e seu índice proliferativo (p < 0,001). Pacientes adultos e pediátricos com AAA, incluindo os que evoluíram para SMD/LMA, têm características morfológicas/imuno-histoquímicas semelhantes. Algumas alterações descritas por Baumann et al. para SMD pediátrica são também encontradas em casos pediátricos e de adultos com AAA. Além disso, o índice proliferativo pode ser aumentado em casos de AAA, este dado não tem correlação com a evolução para SMD/LMA. Alterações morfológicas/imuno-histoquímicas em biópsias de medula óssea em AAA não identificaram um grupo com maior risco de progressão para SMD/LMA em nossa casuística / Acquired Aplastic Anemia (AAA) is a rare disease which progresses to MDS / AML in up to 15% of cases. When this happens, hematopathologists are asked whether the diagnosis of hypocellular Myelodisplastic Syndrome (h-MDS) would not have been confused morphologically with aplastic anemia. This study aims to identify morphological/immunophenotypical findings that could predict this adverse prognosis in adults and children ( < 19y) diagnosed as AAA and verify if those criteria match with the ones described in literature in adult h-MDS and, more recently, in pediatric MDS (Refractory cytopenia of childhood - RCC), contributing to the discussion of this \"grey zone\". We retrospectively analyzed 118 patients/bone marrow (BM) biopsies at the moment of AAA diagnosis at Clinical Hospital of São Paulo Medical School from 1993 to 2012. Diagnosis of AAA was carried out according to classical criteria. Evolution to MDS or AML was considered in the presence of at least one of the findings: significant dysgranulopoiesis or dysmegakaryocytopoiesis, more than 15% ring sideroblasts, blasts in peripheral blood or more than 5% blasts in bone marrow smear and/or biopsy, or in the presence of monosomy or deletion of the long arm of chromosome 7 by cytogenetic analysis (FISH or karyotype) of the BM. All biopsies were submitted to morphological and immunophenotypic (MPO, Glycophorin A, Factor VIII, CD34, CD117 and Ki67) evaluation by two hematopathologists without previous knowledge about the evolution of the patients. Nominal qualitative variables were analyzed by using Fisher\'s exact test to check significant disproportion between the groups. The ordinal qualitative variables were analyzed for differences between groups by Mann-Whitney test. The significance level was 5% (p = 0.05). The correlation between the overall cellularity values of the samples and their proliferative index was evaluated by nonparametric Spearman Rô test. Seventy-one (60,2%) were male, median age 24.4 years (7 months to 76 years old), 42 belongs to the pediatric group and 76 to the adults group. Median follow-up was 5.1y (range, 1 month to 22.1 years). Twelve patients (12%) (6 in each group) progressed to MDS/AML. Evaluation of morphological/immunohistochemical parameters showed irregular distribution of hematopoietic tissue in 59 (50%) cases, median BM overall cellularity of 10% (range, 1 to 40%), marrow dysgranulopoiesis (criteria 1) in 3 (2,5%) cases, abnormal localization of erythropoiesis in 13 (11%) cases, clusters of at least 20 erythroid precursors (criteria 2) in 54 (45.7%) cases, increased number of proerythroblasts (criteria 3) in 32 (27,1%) cases, increased number of mitoses of the erythroid elements (criteria 4) in 24 (20,3%) cases, marrow dysplasia of megakaryocytes (micromegakaryocytes , two or more separeted nuclei, small round nuclei) (criteria 5) in 15 (12,7%) cases, abnormal localization of megakaryocytes in 4 (3,3%) cases, CD34-positive megakaryocytes were not identified, CD34-positive blast cells (criteria 6) in 11 (9,3%) cases, increment in reticulin fibers in 3 (2,5%) cases, and median proliferative index (Ki-67) 30 (range, 0 to 90%). Criteria described by Bennett and Orazi suggestive of h-SMD (criteria 1 and/or 5) were detected in 16 (13,6%) cases. Criteria described by Baumann et al suggestive of childhood MDS (criteria 2 + 3 with or without 4) were observed in 30 (25.4%) cases. There was no statistical difference in morphological/immunohistochemical findings among total population, adults and children who developed and did not develop MDS/AML, including the presence of Bennett and Orazi criteria for h-MDS. Regarding Baumann et al criteria were more frequently identified in the group that did not progress to MDS/AML than the one that did (p=0,036), the opposite of what was expected. But when the criteria were tested in pediatric and adults\' groups separately, the statistical significance was no longer observed. There was a statistical significant correlation between the overall cellularity values of the samples and their proliferative index (p=0,001). Adult and pediatric patients with AAA, including those that progress to MDS/AML, have similar morphological/immunohistochemical characteristics. Some changes described by Baumann et al for pediatric MDS are also found in pediatric and adults\' cases with AAA. In addition, the proliferative index may be increased in cases of AAA and this finding has no correlation with progression to MDS/AML. Morphological/immunohistochemical changes in bone marrow biopsies in AAA have failed to identify a group at higher risk for progression to MDS/AML in our series

Anemia aplástica adquirida (AAA) é doença rara e seu diagnóstico diferencial inclui a Síndrome mielodisplásica hipocelular (SMD-h). A evolução de AAA para SMD/LMA (Síndrome mielodisplásica/Leucemia mieloide aguda) ocorre em até 15% dos casos. Este estudo propõe-se a comparar parâmetros histológicos e imuno-histoquímicos de pacientes adultos e crianças com AAA que evoluíram e não para SMD/LMA. Seu objetivo é avaliar a ocorrência dos critérios morfológicos/imunofenotípicos nas biópsias de medula óssea do grupo pediátrico (<19 anos) com o grupo de adultos, comparar esses critérios associados à evolução para SMD/LMA nestes dois grupos e verificar se estes critérios superpõem-se àqueles descritos na literatura na SMD-hipocelular do adulto e, mais recentemente, na SMD pediátrica (Citopenia refratária da infância - CRI). Espera-se trazer uma contribuição para a discussão da intersecção entre essas entidades e a AAA, estudando essa \"zona cinzenta\" do ponto de vista dos pacientes com AAA, particularmente aqueles que progrediram para SMD/LMA. Foram analisadas, retrospectivamente, 118 biópsias de medula óssea ao diagnóstico de AAA, idiopática ou não, realizadas no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo entre 1993 e 2012. O diagnóstico de AAA foi estabelecido de acordo com critérios clássicos. A evolução de AAA para SMD ou LMA foi considerada na presença de: disgranulopoese ou dismegacariopoese acentuadas, mais de 15% de sideroblastos em anel, blastos em sangue periférico ou mais de 5% de blastos na medula óssea ao mielograma e/ou à biópsia de medula óssea ou na presença de estudo citogenético (FISH ou cariótipo) da medula óssea, apresentando monossomia ou deleção do braço longo do cromossomo 7. Todas as biópsias foram submetidas à análise morfológica e imuno-histoquímica (MPO, Glicoforina A, Fator VIII, CD34, CD117 e Ki-67) por dois hematopatologistas sem conhecimento prévio da evolução dos pacientes. As variáveis qualitativas nominais foram analisadas pelo teste exato de Fisher para verificar se houve desproporção significativa entre os grupos. As variáveis qualitativas ordinais foram analisadas para a diferença entre os grupos pelo teste de Mann-Whitney. O nível de significância adotado foi 5% (p=0,05). A correlação entre os valores de celularidade geral das amostras e seu índice proliferativo foi avaliada pelo teste não paramétrico Rô de Spearman. Setenta e um pacientes (60,2%) eram do gênero masculino com mediana de idade 24,4 anos (mínimo de 7 meses até 76 anos), 42 do grupo pediátrico e 76 adultos, e tempo de seguimento de 5,1 anos (de 1 mês a 22,1 anos). Doze (10,2%) (seis em cada grupo) pacientes evoluíram para SMD/LMA. Avaliação dos parâmetros morfológicos e imuno-histoquímicos mostrou distribuição irregular do tecido hematopoético em 59 (50%) casos, mediana de celularidade geral de 10% (de 1% a 40%), distúrbio de maturação da série granulocítica (critério 1) em três (2,5%) casos, localização anormal da eritropoiese em 13 (11%) casos, agregados de pelo menos 20 precursores eritroides (critério 2), em 54 (45,7%) casos, presença de formas jovens eritroides (proeritroblastos) (critério 3) em 32 (27,1%) casos, aumento do número de mitoses dos elementos eritroides (critério 4) em 24 (20,3%) casos, displasia de megacariócitos (micromegacariócitos, megacariócitos bi ou multinucleados e elementos hipo ou monolobados) (critério 5) em 15 (12,7%) casos, localização anormal de megacariócitos em quatro (3,3%) casos, megacariócitos CD34-positivos não foram identificados, blastos CD34-positivos em 11 (9,3%) casos, reticulogênese discretamente aumentada (grau 1) em três (2,5%) casos e índice proliferativo (Ki-67) com mediana de 30 (de 0% a 90%). Critérios descritos por Bennett e Orazi sugestivos de SMD-h (critérios 1 e/ou 5) foram detectados em 16 (13,6%) casos. Critérios descritos por Baumann et al. sugestivos de SMD da infância (critérios 2 + 3 com ou sem 4) foram observados em 30 (25,4%) casos. Não houve diferença estatística nos achados morfológicos/imuno-histoquímicos entre a população total, adultos e crianças que evoluíram e que não evoluíram para SMD/LMA, incluindo a presença de critérios Bennett e Orazi para SMD-h do adulto. Houve diferença quanto aos critérios de Baumann et al. para CRI, e o grupo que não evoluiu para SMD/LMA apresentou com mais frequência os critérios do que o que evoluiu (p=0,036), ao contrário do previamente suposto. No entanto, ao testar esta hipótese no grupo adulto separado do pediátrico, a diferença estatística não foi comprovada. Houve uma correlação estatisticamente significante entre os valores da celularidade geral das amostras e seu índice proliferativo (p < 0,001). Pacientes adultos e pediátricos com AAA, incluindo os que evoluíram para SMD/LMA, têm características morfológicas/imuno-histoquímicas semelhantes. Algumas alterações descritas por Baumann et al. para SMD pediátrica são também encontradas em casos pediátricos e de adultos com AAA. Além disso, o índice proliferativo pode ser aumentado em casos de AAA, este dado não tem correlação com a evolução para SMD/LMA. Alterações morfológicas/imuno-histoquímicas em biópsias de medula óssea em AAA não identificaram um grupo com maior risco de progressão para SMD/LMA em nossa casuística / Acquired Aplastic Anemia (AAA) is a rare disease which progresses to MDS / AML in up to 15% of cases. When this happens, hematopathologists are asked whether the diagnosis of hypocellular Myelodisplastic Syndrome (h-MDS) would not have been confused morphologically with aplastic anemia. This study aims to identify morphological/immunophenotypical findings that could predict this adverse prognosis in adults and children ( < 19y) diagnosed as AAA and verify if those criteria match with the ones described in literature in adult h-MDS and, more recently, in pediatric MDS (Refractory cytopenia of childhood - RCC), contributing to the discussion of this \"grey zone\". We retrospectively analyzed 118 patients/bone marrow (BM) biopsies at the moment of AAA diagnosis at Clinical Hospital of São Paulo Medical School from 1993 to 2012. Diagnosis of AAA was carried out according to classical criteria. Evolution to MDS or AML was considered in the presence of at least one of the findings: significant dysgranulopoiesis or dysmegakaryocytopoiesis, more than 15% ring sideroblasts, blasts in peripheral blood or more than 5% blasts in bone marrow smear and/or biopsy, or in the presence of monosomy or deletion of the long arm of chromosome 7 by cytogenetic analysis (FISH or karyotype) of the BM. All biopsies were submitted to morphological and immunophenotypic (MPO, Glycophorin A, Factor VIII, CD34, CD117 and Ki67) evaluation by two hematopathologists without previous knowledge about the evolution of the patients. Nominal qualitative variables were analyzed by using Fisher\'s exact test to check significant disproportion between the groups. The ordinal qualitative variables were analyzed for differences between groups by Mann-Whitney test. The significance level was 5% (p = 0.05). The correlation between the overall cellularity values of the samples and their proliferative index was evaluated by nonparametric Spearman Rô test. Seventy-one (60,2%) were male, median age 24.4 years (7 months to 76 years old), 42 belongs to the pediatric group and 76 to the adults group. Median follow-up was 5.1y (range, 1 month to 22.1 years). Twelve patients (12%) (6 in each group) progressed to MDS/AML. Evaluation of morphological/immunohistochemical parameters showed irregular distribution of hematopoietic tissue in 59 (50%) cases, median BM overall cellularity of 10% (range, 1 to 40%), marrow dysgranulopoiesis (criteria 1) in 3 (2,5%) cases, abnormal localization of erythropoiesis in 13 (11%) cases, clusters of at least 20 erythroid precursors (criteria 2) in 54 (45.7%) cases, increased number of proerythroblasts (criteria 3) in 32 (27,1%) cases, increased number of mitoses of the erythroid elements (criteria 4) in 24 (20,3%) cases, marrow dysplasia of megakaryocytes (micromegakaryocytes , two or more separeted nuclei, small round nuclei) (criteria 5) in 15 (12,7%) cases, abnormal localization of megakaryocytes in 4 (3,3%) cases, CD34-positive megakaryocytes were not identified, CD34-positive blast cells (criteria 6) in 11 (9,3%) cases, increment in reticulin fibers in 3 (2,5%) cases, and median proliferative index (Ki-67) 30 (range, 0 to 90%). Criteria described by Bennett and Orazi suggestive of h-SMD (criteria 1 and/or 5) were detected in 16 (13,6%) cases. Criteria described by Baumann et al suggestive of childhood MDS (criteria 2 + 3 with or without 4) were observed in 30 (25.4%) cases. There was no statistical difference in morphological/immunohistochemical findings among total population, adults and children who developed and did not develop MDS/AML, including the presence of Bennett and Orazi criteria for h-MDS. Regarding Baumann et al criteria were more frequently identified in the group that did not progress to MDS/AML than the one that did (p=0,036), the opposite of what was expected. But when the criteria were tested in pediatric and adults\' groups separately, the statistical significance was no longer observed. There was a statistical significant correlation between the overall cellularity values of the samples and their proliferative index (p=0,001). Adult and pediatric patients with AAA, including those that progress to MDS/AML, have similar morphological/immunohistochemical characteristics. Some changes described by Baumann et al for pediatric MDS are also found in pediatric and adults\' cases with AAA. In addition, the proliferative index may be increased in cases of AAA and this finding has no correlation with progression to MDS/AML. Morphological/immunohistochemical changes in bone marrow biopsies in AAA have failed to identify a group at higher risk for progression to MDS/AML in our series

Hematopoiesis is a highly orchestrated process, in which a single hematopoietic stem cell (HSC) gives a rise to all blood cellular components. For myeloid and lymphoid development precise controlled expression of the PU.1 transcription factor is needed. Deletion of PU.1 gene in mouse is lethal and its dysregulation during hematopoietic differentiation is associated with blood malignancies including acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). MDS and AML are serious blood disorders characterized by expansion of immature blood cells and lack of differentiated functional cells. Not only genetic but also epigenetic aberrations represent a very important field for studying pathophysiology of leukemia genesis and dysregulation of the PU.1 gene represents intensively studied candidate mechanism. Modern therapy of selected MDS and subset of AML patients is based on treatment with DNA hypomethylating agent Azacytidine (AZA) interfering in PU.1 gene regulatory mechanism. However, poor response or resistance to this therapy often occurs. In this thesis we present data obtained from AZA-resistant clones of MDS/AML cell line OCI-M2. We analysed DNA methylation and DNA hydroxymethylation at the key regulatory element of the PU.1 gene (URE). We found that these epigenetic modifications at URE...

61 Summary Wilms' tumor gene 1 (WT1) is highly expressed in acute leukemia and other hematological malignancies. It has been therefore suggested as a potential universal marker of minimal residual disease (MRD), particularly in patients with acute myeloid leukemia (AML). Due to controversial results of some of the studies, the role of WT1 in MRD follow-up and WT1 prognostic significance remain unclear. WT1 protein is produced in more than 36 different isoforms. These variants have distinct, partially overlapping functions and their ratio is supposed to influence the final effect of WT1. However, despite the increasing number of studies, the clinical impact of WT1 and its isoforms in acute leukemia have not yet been elucidated. We established a unique qPCR method to assess the expression pattern of the main 4 WT1 isoforms. Using this method, we determined the ratio of WT1 variants in the samples of patients with AML, myelodysplastic syndrome (MDS) and healthy controls. Our data showed that this pattern can distinguish among particular hematological malignancies, but lacks a prognostic significance. Within our international study group we determined the prognostic significance of total WT1 expression in childhood AML. Based on our results of a large cohort of patients we can conclude that WT1 expression at...

Im Rahmen dieser Dissertation wurde retrospektiv die Minimale Resterkrankung von Patienten mit akuter myeloischer Leukämie und Myelodysplastischen Syndrom nach allogener Stammzelltransplantation mit minimaler Konditionierung untersucht. Hierfür wurden vier unterschiedliche Methoden zur Detektion der Minimalen Resterkrankung analysiert. Nach Etablierung einer quantitativen Real-Time PCR für das Wilms Tumor Gen 1 (WT1) im peripheren Blut wurden diese Ergebnisse mit bereits routinemäßig erhobenen Daten des Chimärismus im Gesamtknochenmark und in CD34+ Zellen sowie der Fluoreszenz-in-situ-Hybridisierung (FISH) krankheitsspezifischer chromosomaler Aberrationen von insgesamt 88 Patienten verglichen und statistisch ausgewertet. Es konnte gezeigt werden, dass die Genexpressionanalysen des WT1 sowie die Chimärismusanalysen ein Rezidiv im Gegensatz zu den FISH Analysen vier Wochen im Voraus detektieren können. In Reiceiver Operating Curve Analysen wurden eine WT1 Expression von > 24 WT1/10.000 ABL1 Kopien und der Abfall des CD34+ Spenderchimärismus von ≥ 5% als diagnostisch stärkste Methoden identifiziert. In uni- und multivariaten Analysen von insgesamt 20 Parametern wurden die beiden Methoden als unabhängige Variablen für ein frühes Rezidiv, progressionsfreies Überleben und Gesamtüberleben bestätigt. Kombiniert man beide Methoden, so kann bei jeweiligem negativen Testergebnis ein Rezidiv innerhalb der nächsten vier Wochen nahezu ausgeschlossen werden.

Myelodysplastic syndrome (MDS) with deletion of the long arm of the chromosome 5 (5q - syndrome, del( 5q)) can be characterized by anemia, macrocytosis, a normal or high platelet count, and hypolobulated megakaryocytes in the bone marrow. 5q - syndrome belongs to low - risk MDS, which means low risk to transform to acute myeloid leukemia. 5q - syndrome is ass ociated with female predominance and older age. Another sign is transfusion burden that is treated by erythropoiesis - stimulating agents (ESA) as erythropoietin (EPO). Moreover, the response of MDS patients is around 30 - 60% with the median of the response b eing ~ 24 months. The second line of treatment is lenalidomide (LEN) which is a derivate of teratogenic analog thalidomide. LEN increases erythropoiesis and inhibits the growth of del(5q) erythroid progenitors in vivo and it does not have a significant effe ct on the growth of normal CD34+ progenitors or cytogenetically normal progenitors in MDS with del(5q) clones. LEN is used as therapy in multiple myeloma, myelodysplastic syndrome, and lymphoma. LEN is an expensive agent and not every MDS patient re sponds to this therapy. This is a reason why is a need to find a biomarker for the determination of successful treatment. Some multiple myeloma studies showed that cereblon can be the biomarker...