Découverte de nouveaux marqueurs pharmacogénomiques de la maladie du greffon contre l'hôte en transplantation de cellules souches hématopoïétiques

La transplantation de cellules souches hématopoïétiques (CSH) constitue une avenue thérapeutique potentiellement curative pour plusieurs cancers hématologiques comme la leucémie. L’utilisation d’une thérapie immunosuppressive pour prévenir la maladie du greffon contre l’hôte (GvHD) est un déterminant majeur du succès de la greffe. Malgré tout, cette complication survient chez 25 à 50% des transplantés et est une cause majeure de mortalité. L’optimisation du régime d'immunosuppression est un facteur facilement modifiable qui pourrait améliorer le pronostic des patients. Particulièrement, les polymorphismes du génome du donneur ou du receveur dans les voies pharmacogénomiques des immunosuppresseurs pourraient influencer l’exposition et l’action de ces médicaments, de même que le pronostic du patient. Le profilage de 20 pharmacogènes prioritaires chez des paires de donneurs-receveurs en greffe de CSH a permis d’identifier des variations génétiques liées au risque de la GvHD aiguë. Principalement, le statut génétique du receveur pour les protéines ABCC1 et ABCC2, impliquées dans le transport du méthotrexate (MTX), ainsi que des cibles moléculaires de ce médicament (ATIC et MTHFR) ont été associées au risque de GvHD aiguë. Similairement, le NFATc1, codant pour une cible moléculaire de la cyclosporine, augmentait lui aussi le risque de la maladie. Les porteurs de deux génotypes à risque et plus étaient particulièrement prédisposés à développer cette complication. Par surcroît, le statut génétique du donneur influençait également le pronostic du receveur après la greffe. Entre autres, des allèles protecteurs ont été identifiés dans les voies liées au transport (SLC19A1) et à l’action du MTX (DHFR). Inversement, NFATc2 a été associé à une augmentation du risque de GvHD aiguë. Afin de mieux comprendre les associations observées entre ces marqueurs génétiques et le risque de GvHD aiguë, une étude prospective innovante est en cours chez des greffés de CSH. Cette étude permettra d’étudier comment la génétique du patient ou du donneur peut influencer la pharmacocinétique et la pharmacodynamie des immunosuppresseurs, de même que leurs liens avec la GvHD aiguë. Ces paramètres sont quantifiés grâce à des approches analytiques que nous avons mises au point afin de répondre aux besoins spécifiques et uniques de cette étude. Les approches proposées dans cette thèse sont complémentaires aux méthodes classiques de suivi des immunosuppresseurs et pourraient aider à optimiser la pharmacothérapie du patient. Une meilleure identification des patients à haut risque de GvHD aiguë avant la greffe, basée sur des marqueurs pharmacogénomiques identitaires, pourrait guider le choix de la prophylaxie immunosuppressive, et ainsi améliorer l’issue clinique de la greffe.Hematopoietic stem cells transplantation (HSCT) is a potentially curative therapy for several hematological cancers such as leukemia. Following transplantation, effective immunosuppression prophylaxis is mandatory to prevent the graft-versus-host disease (GvHD) and improved the clinical outcome. However, GvHD still occurs in 25-50% of transplanted patient and is associated with high mortality rate. Optimization of immunosuppressive therapy is an easily modifiable factor that can improve the prognosis of patient after HSCT. In particular, polymorphisms of recipient and donor in genes with functions related to drugs transport, metabolism and action might influence the exposure and the efficacy of immunosuppressive therapy, and thus the clinical outcome. The evaluation of 20 candidate pharmacogenes in donor-recipient pairs of HSCT identified genetic polymorphisms associated with the risk of GvHD. Recipient genetic status for ABCC1 and ABCC2, related to methotrexate (MTX) transport, as well as polymorphisms in genes encoding molecular targets (ATIC and MTHFR) of this drug, exhibit a remarkable influence on acute GvHD prevalence. Similarly, the cyclosporin molecular target NFATc1 also increases the risk of GvHD. Importantly, the presence of ≥2 of these SNPs was found to be associated with high risk of developing severe grade of acute GvHD. In donor, we identified protective alleles in pathways related to transport (SLC19A1) and action (DHFR) of MTX. Conversely, NFATc2 enhances the risk of acute GvHD. To improve our understanding of the process behind these associations, we have an ongoing prospective study in HSCT. This innovative study will provide the opportunity to evaluate the influence of such genetic markers on the pharmacokinetic and pharmacodynamic of immunosuppressive drugs, as well as their relation with the risk of GvHD. For the specific needs of our study, we have developed two analytical methods based on mass spectrometry. The approaches we proposed in this thesis are complementary to conventional monitoring method and are promising tools to optimize drug therapy in HSCT. Identification of such biomarkers assessed before transplantation can help personalized patient care in order to prevent GvHD and improve survival

Mémento 2 : Résidences 1999-2000

This richly illustrated catalogue documents the work of 35 artists who took part in six residencies (including two events - La Cueillette and La Ruche) that took place in 1999 and 2000 at Centre Est-Nord-Est. The centre’s director, F. Michel, describes the nature and purpose of the residencies as well as that of the catalogue : to reflect each participant’s experience. Includes brief comments by the artist on their work and on their stay. Text in French and English. Biographical notes

Title Page In vitro investigation of human UDP-glucuronosyltransferase isoforms responsible for tacrolimus glucuronidation: predominant contribution of UGT1A4. Running Title Page Running title: Tacrolimus glucuronidation by UGT1A4

Abstract Tacrolimus (Tacro) is a po tent immunosuppressant and a ce ntral agent in prevention of posttransplantation rejection. Tacro is characterized by a nar row therapeutic index and wide interindividual pharmacokinetic fluctuation. The contribution of human UDP-glucuronosyltransferase in its metabolism has not been extensively studied. In vitro metabolism studies support that the liver produced Tacro-glucuronide (Tacro-G) while its formation was minimal or undetectable in the presence of intestine and kidney microsomes. Among 17 human UGTs tested, UGT1A4 was the sole enzyme involved in Tacro-G formation. This conclusion is supported by the finding of inhibition with a specific substrate of UGT1A4 lamotrigine with K i values highly similar for b oth human liver and UGT1A4 microsomes and the correlation with trifluoperazine-glucuronide formation by liver microsomes (rs= 0.551; p=0.02). Formation of Tacro-G by liver samples was variable between individuals (6.4-fold variation; n=16) and common non-synonymous variants may contribute to this variability. In the HEK293 cellular model, no significant differences in e nzyme kinetics could be revealed for UGT1A4*2 (P 24 T) and * 3 (L 48 V) while the allozyme *4 (R 11 W) displayed a 2-fold higher velocity (p<0.01) compared to the UGT1A4*1 enzyme preparation. In human liver samples, carriers of the UGT1A4 variants did not display statistically different efficiency in Tacro-G formation compared to homozygote for the reference genotype UGT1A4*1/*1. We conclude that UGT1A4 is the major isoform involved in Tacro glucuronidation while additional studies are required to assess the contribution of UGT1A4 genetic factors in tacrolimus glucuronidation variability. DMD #39040

Early Nutritional Intervention to Promote Healthy Eating Habits in Pediatric Oncology: A Feasibility Study

This study aims to describe the feasibility of a nutritional intervention that promotes healthy eating habits early after cancer pediatric diagnosis in patients and their parents. Participants were recruited 4 to 12 weeks after cancer diagnosis as part of the VIE study. The one-year nutritional intervention included an initial evaluation and 6 follow-up visits every 2 months with a registered dietician. The feasibility assessment included rates of retention, participation, attendance, completion of study measures, and participants’ engagement. A preliminary evaluation of the intervention\u27s impact on the participants’ dietary intakes was conducted. A total of 62 participants were included in the study (51.6% male, mean age = 8.5 years, mean time since diagnosis = 13.2 weeks). The retention and attendance rates were 72.6% and 71.3%, respectively. Attendance to follow-up visits declined over time, from 83.9% to 48.9%. A majority of participants had high participation (50.8%) and high engagement (56.4%). Measures of body-mass-index or weight-for-length ratio and dietary 24-h recalls were the procedures with the highest completion rates. Participants with refractory disease or relapse were less likely to complete the intervention. Post-intervention, participants (n = 21) had a lower sodium intake compared to the initial evaluation. These results suggest that a nutritional intervention that involves patients and parents early after a pediatric cancer diagnosis is feasible

Parents’ Experiences with Home-Based Oral Chemotherapy Prescribed to a Child Diagnosed with Acute Lymphoblastic Leukemia: A Qualitative Study

Acute lymphoblastic leukemia (ALL) is the most common type of cancer in children. Treatment includes home-based oral chemotherapies (OCs) (e.g., 6-mercaptopurine and dexamethasone) taken for 2 to 3 years. The management of OC can be challenging for children and their parents. However, the multifaceted experience of families with children taking OC for ALL is largely undescribed. We report the experience with these OCs from the parents’ perspective. We conducted a qualitative descriptive study. Semi-structured interviews were conducted with the parents of children with ALL aged < 15 years, followed in a specialized university-affiliated center. The interviews were fully transcribed and thematically analyzed. Thirteen of the seventeen eligible parents (76.5%) participated in the study. The parents’ motivation to follow the recommendations provided by the multidisciplinary care team regarding OC was very high. The quantity and the quality of the information received were judged adequate, and the parents reported feeling knowledgeable enough to take charge of the OC at home. Adapting to the consequences of OC on family daily life was collectively identified as the biggest challenge. This includes developing and maintaining a strict daily routine, adapting to the child’s neurobehavioral changes during dexamethasone days and adapting family social life. Our findings have several implications for enhancing the support offered to families with home-based OC for ALL. Supportive interventions should consider the family as a whole and their needs should be regularly monitored. Specific attention should be paid to the development and maintenance of a routine, to the parental burden, and to the emotional impact, especially regarding dexamethasone