A neutropenia induzida pela quimioterapia é o mais comum efeito adverso da quimioterapia sistêmica para o câncer e é frequentemente complicada por neutropenia febril (NF). O uso profilático de fatores de crescimento hematopoiéticos pode reduzir o risco, a severidade e a duração da NF. Na prática clínica atual, a decisão de administrar ao paciente profilaxia com fatores de crescimento é baseada principalmente no potencial mielotóxico dos esquemas de QT, mas riscos específicos dos regimes não são definidos. Em muitos estudos, a toxicidade da quimioterapia é analizada em termos de alta dosagem versus baixa dosagem, sem uma regra geral que considere os diferentes esquemas de QT em uma única escala. O objetivo desse estudo é validar uma classificação de toxicidade de um esquema de QT e avaliar sua utilidade em um modelo de predição de risco de neutropenia febril em pacientes com câncer hematológico no começo de um ciclo de quimioterapia. Foram avaliados prospectivamente duzentos e sessenta e oito pacientes e acompanhados durante 1053 ciclos de quimioterapia na Bélgica, entre 2001 e 2005. Informações relevantes foram coletadas no começo do primeiro ciclo e o número de dias de neutropenia febril foi contabilizado no acompanhamento dos pacientes [dicotomizada (sem neutropenia versus >= dia de NF)]. A relação entre o desfecho e as co-variáveis foi analisada usando a Equação de Estimativa Generalizada (GEE). Um regime de quimioterapia agressiva é o maior preditor de NF [razão de chances (OR) 5.2 (3.2-8.4)]. Os outros preditores independentes são: doença subjacente, o comprometimento de medula óssea, superfície corporal <= 2m², uma contagem pré-tratamento de monócitos <150µl e a interação entre o primeiro ciclo na mesma linha de tratamento e uma dosagem de hemoglobina pré-tratamento. Usando as estimativas dos coeficientes de regressão, uma regra de predição clínica de NF foi desenvolvida com essas características: sensibilidade 78.6%, especificidade 62.3%, valor preditivo positivo de 42.7%% e um valor preditivo negativo de 89.1%. Estudos posteriores são necessários para validar esse escore bem como investigar novos potenciais fatores com o intuito de melhor prever a NF. / Chemotherapy-induced neutropenia is the most common adverse effect of chemotherapy and is often complicated by febrile neutropenia (FN). As prophylactic use of colonystimulating factors (CSF) can reduce the risk, severity, and duration of FN, it is of great importance to identify as soon as possible after or even before the start of chemotherapy, the patients who will develop FN. In the current clinical practice, the decision to give to the patient a colony-stimulating factor (CSF) prophylaxis is mainly based on the myelosuppressive potential of the chemotherapy regimen. The objective of this study is to validate a classification of aggressiveness of a chemotherapy regimen and to evaluate its usefulness in a risk prediction model of FN in patients with hematological cancer at the beginning of a chemotherapy cycle. Two hundred and sixty-six patients were prospectively enrolled and followed during 1053 cycles. Relevant patient informations were collected at the beginning of the first cycle and the number of days of FN were counted in the follow-up [dichotomized (no FN versus>= 1 day of FN)]. Aggressive chemotherapy regimen is the major predictor of FN [odds ratio 5.2 (3.2 - 8.4)]. The other independent predictors are the underlying disease, an involvement of bone marrow, body surface<= 2m², a baseline monocyte count <150/µl and the interaction between the first cycle in the same treatment line and a baseline hemoglobin dosage. A rule of prediction of FN was computed with these characteristics: sensitivity 78.6%, specificity 62.3%, positive predictive value 42.7% and negative predictive value 89.1%. Further studies are needed to validate this score.

In today’s medical science studies, many tumor markers are being used to monitor cancer cell proliferation, but the number of assays for analysis of these markers are few. The aim of this study was to find an easier and more time-efficient way to measure the activity of a specific tumor marker called tymidine kinase 1 (TK1). This tumor marker is an important enzyme involved in cell proliferation and is a key enzyme in the salvage pathway. TK1 activity is related to the occurrence of hematological malignancies and cell activity and therefore have been used as a marker when monitoring this group of patients in treatment. Measurement of the enzyme activity in this study was performed by using an oligonucleotide assay. Detection of the enzyme activity in whole blood and in plasma has not previously been shown. The TK1 activity measured in whole blood and plasma correlated with TK1 activity measured in serum (R2=0,8651 and R2 =0,9845, respectively). It was found that it is possible to determine the TK1 activity in whole blood but only if the activity was measured on the same day as the blood samples were taken. The results shows that the activity measurement of TK1 in plasma and whole blood can be used as a marker to verify patients' therapy in cancer care. This study is only the beginning and further investigations should be made in the future to determine if the method that is subject to this study has the requested effects.

A neutropenia induzida pela quimioterapia é o mais comum efeito adverso da quimioterapia sistêmica para o câncer e é frequentemente complicada por neutropenia febril (NF). O uso profilático de fatores de crescimento hematopoiéticos pode reduzir o risco, a severidade e a duração da NF. Na prática clínica atual, a decisão de administrar ao paciente profilaxia com fatores de crescimento é baseada principalmente no potencial mielotóxico dos esquemas de QT, mas riscos específicos dos regimes não são definidos. Em muitos estudos, a toxicidade da quimioterapia é analizada em termos de alta dosagem versus baixa dosagem, sem uma regra geral que considere os diferentes esquemas de QT em uma única escala. O objetivo desse estudo é validar uma classificação de toxicidade de um esquema de QT e avaliar sua utilidade em um modelo de predição de risco de neutropenia febril em pacientes com câncer hematológico no começo de um ciclo de quimioterapia. Foram avaliados prospectivamente duzentos e sessenta e oito pacientes e acompanhados durante 1053 ciclos de quimioterapia na Bélgica, entre 2001 e 2005. Informações relevantes foram coletadas no começo do primeiro ciclo e o número de dias de neutropenia febril foi contabilizado no acompanhamento dos pacientes [dicotomizada (sem neutropenia versus >= dia de NF)]. A relação entre o desfecho e as co-variáveis foi analisada usando a Equação de Estimativa Generalizada (GEE). Um regime de quimioterapia agressiva é o maior preditor de NF [razão de chances (OR) 5.2 (3.2-8.4)]. Os outros preditores independentes são: doença subjacente, o comprometimento de medula óssea, superfície corporal <= 2m², uma contagem pré-tratamento de monócitos <150µl e a interação entre o primeiro ciclo na mesma linha de tratamento e uma dosagem de hemoglobina pré-tratamento. Usando as estimativas dos coeficientes de regressão, uma regra de predição clínica de NF foi desenvolvida com essas características: sensibilidade 78.6%, especificidade 62.3%, valor preditivo positivo de 42.7%% e um valor preditivo negativo de 89.1%. Estudos posteriores são necessários para validar esse escore bem como investigar novos potenciais fatores com o intuito de melhor prever a NF. / Chemotherapy-induced neutropenia is the most common adverse effect of chemotherapy and is often complicated by febrile neutropenia (FN). As prophylactic use of colonystimulating factors (CSF) can reduce the risk, severity, and duration of FN, it is of great importance to identify as soon as possible after or even before the start of chemotherapy, the patients who will develop FN. In the current clinical practice, the decision to give to the patient a colony-stimulating factor (CSF) prophylaxis is mainly based on the myelosuppressive potential of the chemotherapy regimen. The objective of this study is to validate a classification of aggressiveness of a chemotherapy regimen and to evaluate its usefulness in a risk prediction model of FN in patients with hematological cancer at the beginning of a chemotherapy cycle. Two hundred and sixty-six patients were prospectively enrolled and followed during 1053 cycles. Relevant patient informations were collected at the beginning of the first cycle and the number of days of FN were counted in the follow-up [dichotomized (no FN versus>= 1 day of FN)]. Aggressive chemotherapy regimen is the major predictor of FN [odds ratio 5.2 (3.2 - 8.4)]. The other independent predictors are the underlying disease, an involvement of bone marrow, body surface<= 2m², a baseline monocyte count <150/µl and the interaction between the first cycle in the same treatment line and a baseline hemoglobin dosage. A rule of prediction of FN was computed with these characteristics: sensitivity 78.6%, specificity 62.3%, positive predictive value 42.7% and negative predictive value 89.1%. Further studies are needed to validate this score.

Résumé : Cette thèse porte sur le rôle de deux expositions environnementales encore peu étudiées et pouvant influer sur l’incidence des hémopathies malignes (HME) de l’enfant : les rayons ultraviolets (UV) et les pesticides liés aux activités agricoles.Les leucémies (LA) et lymphomes de l’enfant sont les deux types principaux de HME et représentent respectivement environ 470 et 200 nouveaux cas par an en France. Leur prise en charge thérapeutique et leur survie ont fait d’immenses progrès, cependant la connaissance de leurs facteurs de risque est encore très partielle.Les études sur les effets des UV dans les cancers de l’enfant sont peu développées. Plusieurs méta-analyses récentes concluent à une augmentation du risque de LA chez l’enfant lors d’une exposition professionnelle ou domestique de la mère aux pesticides pendant la grossesse. L’exposition aux pesticides d’origine agricole a été moins étudiée, et les résultats sont hétérogènes.La première partie, écologique, de ce travail s’intéresse à l’exposition résidentielle aux UV. Une étude a été réalisée à partir des observations du Registre National des Hémopathies malignes de l’Enfant (RNHE) faites sur une longue période, entre 1990-2009 et sur l’ensemble de la France métropolitaine (9 082 cas de LA et 3 563 cas de lymphomes). Les données de l’exposition aux UV résidentiels étaient issues de la base EUROSUN. Une moyenne quotidienne d’exposition aux UV résidentiels sur l’ensemble de la période 1988-2007 à l’échelle communale a été considérée. Une augmentation significative de l’incidence des leucémies aiguës lymphoblastiques à précurseurs B (LAL-Pré B) chez les moins de 5 ans a été observée avec l’exposition aux UV résidentiels au moment du diagnostic. L’association n’était pas modifiée après une stratification par périodes ; par tranches d’unités urbaines ; par grandes régions, et par un indice de défaveur français. Une deuxième étude, individuelle, sur les UV ne trouvait pas de modification de l’association en prenant en compte le rôle de facteurs individuels soupçonnés d’être associés aux LAL et en regardant l’exposition à la naissance. Les données individuelles de ces facteurs provenaient de deux études cas-témoins en population générale, l’enquête ESCALE (2003-2004) et l’enquête ESTELLE (2010-2011).La dernière partie de la thèse se penche sur l’exposition résidentielle aux pesticides liés aux activités agricoles. Cette étude s’appuie sur les données du RNHE, recueillant 10 994 cas de LA et 4 301 cas de lymphomes sur la période 1990-2013. L’intensité de l’activité agricole dans le canton de résidence au moment du diagnostic a été choisie comme proxy de l’exposition aux pesticides. Cette intensité a été à partir des données cantonales du Recensement général Agricole de 2000. Dans cette première approche aucune association n’a été mise en évidence entre les HME et la part de Surface Agricole Utile (SAU) totale. Les analyses par grands types de cultures montrent, dans cette première approche, une association positive et significative entre l’intensité de cultures en oléagineux et l’incidence des LAL Pré-B et des lymphomes de Burkitt. Des analyses de sensibilité montraient des résultats hétérogènes par période d’étude. / Abstract: This thesis deals with the role of two environmental exposures not much studied and that could have an impact on the incidence of childhood hematological malignancies (CHM): ultraviolet radiation (UV) and agricultural pesticides.The two major diagnostic groups are acute leukemia (AL) and lymphomas and represent respectively around 470 and 200 new cases per year in France. Despite the progress made in improving therapeutic caring and survival, the etiology of these cancers remains largely unknown.There are very few studies on the association between UV and these cancers. Meta-analyses found a coherent association between childhood AL and parental professional or domestic pesticides exposure during pregnancy. However the association with residential exposure to agricultural pesticides has been less studied and results are heterogeneous.The first, ecological, part of the thesis addressed the associations between residential UV exposure at diagnosis and the incidence of types and subtypes of CHM in France. The 9,082 cases of acute leukemia (AL) and 3,563 cases of lymphoma diagnosed before the age of 15 years from 1990 to 2009 were provided by the French National Registry of Childhood Hematological Malignancies. UV data from 1988 to 2007 were extracted from the EUROSUN database. The annual daily average UV exposure of the children estimated at the municipalities of residence was considered. There was a significant increase in precursor B-cell acute lymphoblastic leukemia (PBC-ALL) in children aged less than 5 years with residential exposure to UV. The results remained stable in analyses stratifying by deprivation index or degree of urbanization of the municipalities.A second, individual, study found no change in the association between UV and PBC-ALL after taking into account the influence of suspected individual risk factors for ALL, and evaluated this association at birth. Individual data were collected by interviews in the ESCALE (2003-2004) and ESTELLE (2010-2011) nationwide case-control studies.The last part of this work focused on the residential exposure to agricultural pesticides. The 10,994 cases of AL and the 4,301 cases of lymphomas diagnosed among children less than 15 years old were obtained from the French National Registry of Childhood Hematological Malignancies over the period 1990-2013. Intensity of agricultural activities by Canton was used as a proxy of residential agricultural pesticides exposure. This proxy was estimated from the 2000 French agricultural census data. At this first step of the analysis, no associations were found between total agricultural area and incidence of CHM. Analyses by types of crops showed, at this first step, a significant association between oilseeds and PBC-ALL and Burkitt lymphoma. Sensitivity analyses evidenced heterogeneous results by time period.

Hintergrund: Patienten mit hämatologischen Neoplasien sind in den spezialisierten palliativmedizinischen Versorgungsstrukturen im Vergleich zu Patienten mit soliden Tumoren unterrepräsentiert. Im Falle eines palliativmedizinischen Einbezuges erfolgt dieser deutlich später. Hierfür werden verschiedene Gründe diskutiert: Schwierigkeiten in der Prognosefestlegung, das Auftreten von akuten Komplikationen und plötzlichem Krankheitsprogress oder die Notwendigkeit von fortgesetzten invasiven Therapiemaßnahmen. Methodik: In dieser Studie wurden die deutschlandweit erhobenen Daten der Hospiz- und Palliativerhebung (HOPE) von 2006 bis 2008 sekundär ausgewertet, um die klinische Charakteristik und spezielle Therapie- und Versorgungsaspekte von hämatologischen Patienten in spezialisierten Palliativeinrichtungen zu analysieren und mit denen von Patienten mit überwiegend soliden Tumoren sowie mit den prospektiv gewonnen Daten von inkurabel hämatologisch erkrankten Patienten der Abteilung für Hämatologie und Onkologie der Universitätsmedizin Göttingen ohne Anschluss an eine palliativmedizinische Versorgung zu vergleichen. Ergebnisse: Von den insgesamt 5.487 in der HOPE-Erhebung erfassten Palliativpatienten wiesen nur 220 Patienten (4%) eine maligne hämatologische Grunderkrankung auf. Es wurden 50 inkurabel erkrankte hämatologische Patienten der Klinik für Hämatologie und Onkologie erfasst, die einen deutlich besseren Allgemeinzustand und subjektives Gesamtbefinden aufwiesen, weniger fokale Symptome, zeigten, jedoch häufiger an psychischen Symptomen litten, als die Patienten in den palliativmedizinischen Einrichtungen. Hämatologische Patienten erhielten deutlich mehr interventionelle Therapiemaßnahmen wie fortgesetzte palliative Chemotherapie oder Transfusionen. Diskussion: Die Ergebnisse dieser Arbeit zeigen die spezifischen Charakteristika und Bedürfnisse von Patienten mit fortgeschrittenen malignen hämatologischen Grunderkrankungen und machen so die speziellen Anforderungen an die palliativmedizinische Versorgung dieser Patientengruppe deutlich. Auch auf Grundlage dieser Erkenntnisse bedarf es der Entwicklung von neuen, flexiblen Behandlungskonzepten, um hämato-onkologischen Patienten den Zugang zur Palliativversorgung zu erleichtern bzw. eine frühere und bedürfnis- anstatt prognoseorientierte palliativmedizinische Mitbehandlung zu ermöglichen.

La protéine p53 (« Gardien du génome ») doit être altérée pour que le cancer puisse se développer. Les nombreuses thérapies anti-cancéreuses disponibles sont très efficaces mais la réponse clinique est souvent transitoire et les cancers disséminés rechutent ou progressent du fait de l'évolution de sous-populations cancéreuses résistantes au traitement, impliquant souvent TP53 qui est le gène le plus muté dans les formes agressives de nombreux cancers. Nous l’avons étudié dans la leucémie lymphoïde chronique (LLC) et les syndromes myélodysplasiques avec délétion 5q (SMD del(5q)). Grâce à l’étude rétrospective longitudinale de 40 patients atteints de SMD del(5q), nous avons généré des données de NGS ciblé et montré que le statut mutationnel de TP53 au diagnostic ne permettait pas de prédire la progression tumorale, contrairement à ce qui avait été publié précédemment (Jädersten et al., JCO 2011). Nous avons montré que c’était l’évolution clonale du gène TP53 qui était l’élément clé de la progression des SMD del(5q). Nous avons observé de nombreuses émergences de clones mutés entre le stade diagnostique et un stade ultérieur de la maladie, toujours après initiation du traitement par lénalidomide.Le lénalidomide a été approuvé comme nouveau traitement spécifique et très efficace contre l’anémie liée aux SMD del(5q), permettant à la plupart des patients d’être indépendants des transfusions sanguines. Le lénalidomide permet souvent d’éradiquer le clone tumoral porteur de l’anomalie génétique del(5q) isolée, induisant une rémission clinique. Malheureusement, cette rémission est courte avec une durée médiane de 2 ans, puis, dans environ 1 cas sur 2, survient une transformation en leucémie aiguë secondaire de pronostic péjoratif.Nous avons étudié un possible lien entre le traitement par lénalidomide et l’évolution clonale de TP53 par annotation clinico-bio-thérapeutiques des résultats de séquençage de TP53 chez les 24 patients dont les échantillons séquentiels avaient été analysés. Dans notre étude, les patients avec progression tumorale (dont 10 évolutions clonales de TP53 et 1 évolution clonale de RUNX1) avaient reçu une dose cumulée de lénalidomide supérieure à celle reçue par les patients dont la tumeur était restée stable (p = 0.036). Nous avons observé chez plusieurs patients que l’éradication de la tumeur n’était pas utile à l’amélioration de la qualité de vie des patients. La non-éradication semblait même permettre un maintien de l’équilibre clonal et une compétition entre les différents sous-clones de la tumeur, résistants ou non au lénalidomide.Nous discutons de l’évolution de l'écologie de la tumeur au cours du traitement, i.e., l’évolution de ses interactions avec son micro-environnement qui se modifie après chaque nouvelle dose de traitement. Un modèle évolutif dit théorie de la thérapie adaptative, développée récemment remet en question les protocoles conventionnels de thérapie anti-cancéreuse qui préconisent souvent d'administrer la dose maximale tolérée par le patient (Gatenby, 2009). Elle suggère que la dose minimale efficace présenterait l’avantage de ne pas éradiquer les cellules cancéreuses sensibles au traitement pour qu'elles restent en compétition avec les cellules cancéreuses résistantes et limiter la progression ou la rechute. Nous suggérons de prendre en compte également la diminution des effets indésirables pour le patient, améliorant ainsi sa qualité de vie, et enfin la diminution des dépenses de santé pour la collectivité. A ce jour, peu d’études cliniques évaluent l’intérêt de l’adoption de tels protocoles de thérapie adaptative.Néanmoins, des modèles in vivo (xénogreffes) et in silico (modèles statistiques) ont permis d’analyser la dynamique évolutive des populations tumorales en fonction du traitement reçu. Ces modèles prédisent que la survie de l’hôte peut être maximisée par la mise en place d’une thérapie adaptative. / P53 protein is named «guardian of the genome » because it must be altered to let cancer grow.TP53 is the most mutated gene in agressive cancers.Numerous systemic therapies are successful for treatment of disseminated cancers. However, clinical response is often transient, and cancer undergo relapse or progression due to emergence of resistant populations. These latter often harbour TP53 mutations. We studied TP53 in chronic lymphoid leukemia (CLL) and lower-risk myelodysplastic syndroms with del(5q), MDS del(5q). We conducted a retrospective longitudinal study in 40 patients suffering from MDS del(5q). We obtained targeted NGS data showing that TP53 mutational status at diagnosis could not predict tumor progression, by contrast with previously published data (Jädersten et al., JCO 2011). We show that TP53 clonal evolution is the key feature of tumor progression in MDS del(5q). We observed numerous mutated sub-clones emerging between diagnosis and follow-up. In our study, this emergence always followed onset of lenalidomide treatment. Lenalidomide was recently approved as a new therapy specifically improving anemia in patients with MDS del(5q). It allows most patients to become red-blood-cells-transfusion independent. Lenalidomide often eradicates the major tumor clone harbouring the isolated genetic abnormality deletion (5q) and allows clinical remission. Unfortunately, this remission is short (median, 2 years) and is followed, in 1 case out of 2, by a secondary acute leukemic transformation with a very poor prognosis.We studied the issue of a possible link between lenalidomide therapy and TP53 clonal evolution by annotating TP53 sequencing results with acute biological, clinical and therapeutic features in the 24 patients with sequential samples analyzed. In our study, patients with tumor progression (10 TP53 clonal evolution and 1 RUNX1 clonal evolution) were given a higher cumulative dose of lenalidomide compared to patients with stable disease (p = 0.036). Similarly to « adaptive therapy theory »(Gatenby 2009), we observed that eradication of the tumor wasn’t useful for improvement of quality of life. Absence of eradication might even allow to maintain a clonal equilibrium and a clonal competition between the distinct tumor sub-clones, resistant to lenalidomide or not, and therefore maintain stable disease.This theory of adaptive therapy questions the classical protocols of treatments against cancer, in which the maximal tolerated dose is preferred to the minimal effective dose. The latter might however slow down cancer progression or cancer relapse, with decreased side effects in patients, and decreased health costs.To date, few clinical trials (if any) questions such protocols of adaptive therapy. However, in vivo experiments (xenografts) and in silico statistical models allowed to study evolutionary dynamics of tumor sub-populations with and without therapy.The models predict that host survival can be maximized if “treatment-for-cure strategy” is replaced by “treatment-for-stability.” Specifically, the models predict that an optimal treatment strategy will modulate therapy to maintain a stable population of chemosensitive cells that can, in turn, suppress the growth of resistant populations under normal tumor conditions, Dr Gatenby said.

I proposed the study of two distinct aspects of Ten-Eleven Translocation 2 (TET2) protein for understanding specific functions in different body systems. In Part I, I characterized the molecular mechanisms of Tet2 in the hematological system. As the second member of Ten-Eleven Translocation protein family, TET2 is frequently mutated in leukemic patients. Previous studies have shown that the TET2 mutations frequently occur in 20% myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN), 10% T-cell lymphoma leukemia and 2% B-cell lymphoma leukemia. Genetic mouse models also display distinct phenotypes of various types of hematological malignancies. I performed 5-hydroxymethylcytosine (5hmC) chromatin immunoprecipitation sequencing (ChIP-Seq) and RNA sequencing (RNA-Seq) of hematopoietic stem/progenitor cells to determine whether the deletion of Tet2 can affect the abundance of 5hmC at myeloid, T-cell and B-cell specific gene transcription start sites, which ultimately result in various hematological malignancies. Subsequent Exome sequencing (Exome-Seq) showed that disease-specific genes are mutated in different types of tumors, which suggests that TET2 may protect the genome from being mutated. The direct interaction between TET2 and Mutator S Homolog 6 (MSH6) protein suggests TET2 is involved in DNA mismatch repair. Finally, in vivo mismatch repair studies show that the loss of Tet2 causes a mutator phenotype. Taken together, my data indicate that TET2 binds to MSH6 to protect genome integrity. In Part II, I intended to better understand the role of Tet2 in the nervous system. 5-hydroxymethylcytosine regulates epigenetic modification during neurodevelopment and aging. Thus, Tet2 may play a critical role in regulating adult neurogenesis. To examine the physiological significance of Tet2 in the nervous system, I first showed that the deletion of Tet2 reduces the 5hmC levels in neural stem cells. Mice lacking Tet2 show abnormal hippocampal neurogenesis along with 5hmC alternations at different gene promoters and corresponding gene expression downregulation. Through the luciferase reporter assay, two neural factors Neurogenic differentiation 1 (NeuroD1) and Glial fibrillary acidic protein (Gfap) were down-regulated in Tet2 knockout cells. My results suggest that Tet2 regulates neural stem/progenitor cell proliferation and differentiation in adult brain.

La lutte contre le cancer est certainement l’un des défis majeurs de ce 21ème siècle. Les résistances qui émergent contre les agents de thérapie ciblée présentent un aspect particulièrement épineux de cette problématique. La thèse présentée ici s’inscrit dans ce cadre. Elle vise à développer des molécules bioactives pouvant circonvenir les résistances apparues contre les traitements de certaines hémopathies malignes : la leucémie myéloïde chronique (LMC) et le syndrome myélodysplasique (SMD). Après avoir mis au point une méthodologie de synthèse monotope permettant de transformer un azoture en un 5-alcynyl-1,2,3-triazole, nous avons synthétisé deux séries de produits : nucléosidique et non nucléosidique. Pour chacune de ces séries, des relations structure-activité ont été établies. Après plusieurs cycles d’optimisation, trois composés lead très efficaces contre des lignées cellulaires résistantes de LMC et SMD, ont été sélectionnés. De surcroît, leur mode d’action s’est révélé très intéressant : il repose (partiellement ou entièrement, suivant le composé) sur un processus cellulaire qui connaît un véritable regain d’intérêt, à savoir l’autophagie. Une évaluation in vivo a été réalisée et a permis de valider l’activité prometteuse de notre composé lead nucléosidique. Par ailleurs, des études visant à déterminer la localisation intracellulaire et les cibles moléculaires de nos produits sont actuellement en cours / The fight against cancer is certainly one of the biggest challenges of the 21st century. Resistance that comes up against targeted therapy agents presents a particularly important aspect of this issue. The thesis presented here takes part within that framework. It aims at developing bioactive molecules able to circumvent resistance that have emerged against the treatment of certain hematological malignancies: chronic myeloid leukemia (CML) and myelodysplastic syndrome (MDS). Having developed a one-pot synthesis methodology that converts azides into 5-alkynyl-1,2,3-triazole, we synthesized two series of products: nucleosidic and non-nucleosidic. For each of these series, structure-activity relationships have been established. After running several cycles of optimization, three lead compounds particularly active on resistant cell lines of CML and MDS were selected. Further, their mode of action proved to be very interesting. It is based (partially or fully, depending on the compound) on a cellular process, which is experiencing a real renewed interest, the autophagy. An in vivo evaluation confirmed the promising activity of our nucleosidic lead compound. Moreover, studies aiming at determining the intracellular localization and molecular targets of our products are currently in progress

Indiana University-Purdue University Indianapolis (IUPUI) / Gain-of-function mutations in the KIT receptor tyrosine kinase have been associated with highly malignant human neoplasms. In particular, an acquired somatic mutation at codon 816 in the second catalytic domain of KIT involving an aspartic acid to valine substitution is found in patients with systemic mastocytosis (SM) and acute myeloid leukemia (AML). The presence of this mutation in SM and AML is associated with poor prognosis and overall survival. This mutation changes the conformation of the KIT receptor resulting in altered substrate recognition and constitutive tyrosine autophosphorylation leading to constitutive ligand independent growth. As there are currently no efficacious therapeutic agents against this mutation, this study sought to define novel therapeutic targets that contribute to aberrant signaling downstream from KITD816V that promote transformation of primary hematopoietic stem/progenitor cells in diseases such as AML and SM. This study shows that oncogenic KITD814V (murine homolog) induced myeloproliferative neoplasms (MPN) occurs in the absence of ligand stimulation, and that intracellular tyrosines are important for KITD814V-induced MPN. Among the seven intracellular tyrosines examined, tyrosine 719 alone has a unique role in regulating KITD814V-induced proliferation and survival. Residue tyrosine 719 is vital for activation of the regulatory subunit of phosphatidylinositol 3-kinase (PI3K), p85α, downstream from KITD814V. Downstream effectors of the PI3K signaling pathway, in of leukemic cells bearing KITD814V with an allosteric inhibitor of Pak or its genetic inactivation results in growth repression due to enhanced apoptosis. To assess the role of Rac GEFs in KITD814V induced transformation, EHop-016, an inhibitor of Rac, was used to specifically target Vav1, and found to be a potent inhibitor of human and murine leukemic cell growth. In vivo, the inhibition of Vav or Rac or Pak delayed the onset of MPN and rescued the associated pathology in mice. These studies provide insight on mechanisms and potential novel therapeutic targets for hematological malignancies harboring an oncogenic KIT mutation.