Interactions neurohumorales et signalisations cellulaires impliquées dans le remodelage hypertrophique des artères de résistances : rôle central de l'endothéline

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Personalized cancer medicine: molecular diagnostics, predictive biomarkers, and drug resistance.

The progressive elucidation of the molecular pathogenesis of cancer has fueled the rational development of targeted drugs for patient populations stratified by genetic characteristics. Here we discuss general challenges relating to molecular diagnostics and describe predictive biomarkers for personalized cancer medicine. We also highlight resistance mechanisms for epidermal growth factor receptor (EGFR) kinase inhibitors in lung cancer. We envisage a future requiring the use of longitudinal genome sequencing and other omics technologies alongside combinatorial treatment to overcome cellular and molecular heterogeneity and prevent resistance caused by clonal evolution.

Selective FLT3 inhibition of FLT3-ITD+ acute myeloid leukaemia resulting in secondary D835Y mutation: a model for emerging clinical resistance patterns.

Acquired resistance to selective FLT3 inhibitors is an emerging clinical problem in the treatment of FLT3-ITD(+) acute myeloid leukaemia (AML). The paucity of valid pre-clinical models has restricted investigations to determine the mechanism of acquired therapeutic resistance, thereby limiting the development of effective treatments. We generated selective FLT3 inhibitor-resistant cells by treating the FLT3-ITD(+) human AML cell line MOLM-13 in vitro with the FLT3-selective inhibitor MLN518, and validated the resistant phenotype in vivo and in vitro. The resistant cells, MOLM-13-RES, harboured a new D835Y tyrosine kinase domain (TKD) mutation on the FLT3-ITD(+) allele. Acquired TKD mutations, including D835Y, have recently been identified in FLT3-ITD(+) patients relapsing after treatment with the novel FLT3 inhibitor, AC220. Consistent with this clinical pattern of resistance, MOLM-13-RES cells displayed high relative resistance to AC220 and Sorafenib. Furthermore, treatment of MOLM-13-RES cells with AC220 lead to loss of the FLT3 wild-type allele and the duplication of the FLT3-ITD-D835Y allele. Our FLT3-Aurora kinase inhibitor, CCT137690, successfully inhibited growth of FLT3-ITD-D835Y cells in vitro and in vivo, suggesting that dual FLT3-Aurora inhibition may overcome selective FLT3 inhibitor resistance, in part due to inhibition of Aurora kinase, and may benefit patients with FLT3-mutated AML.

Combinations of ZAP-70, CD38 and IGHV mutational status as predictors of time to first treatment in CLL.

ZAP-70, CD38 and IGHV mutations have all been reported to have prognostic impact in chronic lymphocytic leukemia (CLL), both individually and in paired combinations. We aimed to determine whether the combination of all three factors provided more refined prognostic information concerning the treatment-free interval (TFI) from diagnosis. ZAP-70, CD38 and IGHV mutations were evaluated in 142 patients. Combining all three factors, the ZAP-70-/CD38-/Mutated group showed the longest median TFI (62 months, n = 37), ZAP-70+/CD38+/Unmutated cases the shortest (11 months, n = 37) and cases discordant for > or = 1 factor, an intermediate TFI (27 months, n = 68) (p = 0.006). Analysis of discordant cases revealed values that were otherwise masked when measuring single prognostic factors. The presence or absence of cytogenetic abnormalities did not explain the variability among discordant cases. Simultaneous analysis of ZAP-70, CD38 and IGHV mutations in CLL provides more discriminatory prediction of TFI than any factor alone.

3531: Neoadjuvant radiotherapy (RT) combined with capecitabine (Cape) and sorafenib (Sor) in patients (pts) with locally advanced, k-ras-mutated rectal cancer (LARC): A phase I/II trial SAKK 41/08

Background: K-ras mutation is found in up to 40% of LARC. Sor is a multitarget tyrosine kinase inhibitor including raf and VEGFR and has demonstrated radiosensitizing effects. Sor might improve outcome of standard preoperative radio-chemotherapy in patients with k-ras mutated LARC. Methods: Pts with k-ras mutated T3-4 and/or N+, M0 disease by MRI were included. Recommended doses from phase I part consisted of RT 1.8 Gy/day x25 with Cape 825mg/m2bid x 33 in combination with Sor 400mg/d. The primary endpoint for the phase II part was pathological complete response (pCR) prospectively defined as grade 3 (near complete regression) or 4 (complete regression) in the histological grading system according to Dworak (DC). A pCR rate of 8% or lower was considered uninteresting and of 22% or higher was promising. Secondary endpoints included sphincter preservation, R0 resection, downstaging and safety. Results: 54 pts were treated in 18 centers in Switzerland und Hungary, 40 pts were included into the single arm phase II part. Median dose intensity per day was 100.0% for RT, 98.6% for Cape and 100.0% for Sor respectively. pCR rate was 60.0% (95%CI: 43.3%, 75.1%) by central independent pathological review (15.0% DC grade 4; 45.0% DC grade 3). Sphincter preservation was achieved in 89.5%, R0 resection in 94.7% and downstaging in 81.6% of the pts. The most common grade 3 toxicities included diarrhea (15.0%), skin toxicity outside of the RT field (12.5%), pain (7.5%), skin toxicity in RT field, proctitis, fatigue and cardiac ischemia (each 5.0%). Laboratory AEs grade 3/4 were neutropenia (1 pt grade 4; 1 grade 3), creatinine elevation (1 pt grade 3). Conclusions: The combination of Sor to standard RCT with Cape in k-ras mutated LARC tumors is highly active with acceptable toxicity and deserves further investigation.

Applying Mathematical Models to Study the Role of the Immune System in Chronic Myelogenous Leukemia

Although tyrosine kinase inhibitors (TKIs) such as imatinib have transformed chronic myelogenous leukemia (CML) into a chronic condition, these therapies are not curative in the majority of cases. Most patients must continue TKI therapy indefinitely, a requirement that is both expensive and that compromises a patient's quality of life. While TKIs are known to reduce leukemic cells' proliferative capacity and to induce apoptosis, their effects on leukemic stem cells, the immune system, and the microenvironment are not fully understood. A more complete understanding of their global therapeutic effects would help us to identify any limitations of TKI monotherapy and to address these issues through novel combination therapies. Mathematical models are a complementary tool to experimental and clinical data that can provide valuable insights into the underlying mechanisms of TKI therapy. Previous modeling efforts have focused on CML patients who show biphasic and triphasic exponential declines in BCR-ABL ratio during therapy. However, our patient data indicates that many patients treated with TKIs show fluctuations in BCR-ABL ratio yet are able to achieve durable remissions. To investigate these fluctuations, we construct a mathematical model that integrates CML with a patient's autologous immune response to the disease. In our model, we define an immune window, which is an intermediate range of leukemic concentrations that lead to an effective immune response against CML. While small leukemic concentrations provide insufficient stimulus, large leukemic concentrations actively suppress a patient's immune system, thus limiting it's ability to respond. Our patient data and modeling results suggest that at diagnosis, a patient's high leukemic concentration is able to suppress their immune system. TKI therapy drives the leukemic population into the immune window, allowing the patient's immune cells to expand and eventually mount an efficient response against the residual CML. This response drives the leukemic population below the immune window, causing the immune population to contract and allowing the leukemia to partially recover. The leukemia eventually reenters the immune window, thus stimulating a sequence of weaker immune responses as the two populations approach equilibrium. We hypothesize that a patient's autologous immune response to CML may explain the fluctuations in BCR-ABL ratio that are regularly seen during TKI therapy. These fluctuations may serve as a signature of a patient's individual immune response to CML. By applying our modeling framework to patient data, we are able to construct an immune profile that can then be used to propose patient-specific combination therapies aimed at further reducing a patient's leukemic burden. Our characterization of a patient's anti-leukemia immune response may be especially valuable in the study of drug resistance, treatment cessation, and combination therapy.

Diet, microbes and gut immune responses in the pathogenesis of experimental type 1 diabetes

Type 1diabetes (T1D) is an autoimmune disease, which is influenced by a variety of environmental factors including diet and microbes. These factors affect the homeostasis and the immune system of the gut. This thesis explored the altered regulation of the immune system and the development of diabetes in non-obese diabetic (NOD) mice. Inflammation in the entire intestine of diabetes-prone NOD mice was studied using a novel ex-vivo imaging system of reactive oxygen and nitrogen species (RONS), in relation to two feeding regimens. In parallel, gut barrier integrity and intestinal T-cell activation were assessed. Extra-intestinal manifestations of inflammation and decreased barrier integrity were sought for by studying peritoneal leukocytes. In addition, the role of pectin and xylan as dietary factors involved in diabetes development in NOD mice was explored. NOD mice showed expression of RONS especially in the distal small intestine, which coincided with T-cell activation and increased permeability to macromolecules. The introduction of a casein hydrolysate (hydrolysed milk protein) diet reduced these phenomena, altered the gut microbiota and reduced the incidence of T1D. Extra-intestinally, macrophages appeared in large numbers in the peritoneum of NOD mice after weaning. Peritoneal macrophages (PM) expressed high levels of interleukin-1 receptor associated kinase M (IRAK-M), which was indicative of exposure to ligands of toll-like receptor 4 (TLR-4) such as bacterial lipopolysaccharide (LPS). Intraperitoneal LPS injections activated T cells in the pancreatic lymph nodes (PaLN) and thus, therefore potentially could activate islet-specific T cells. Addition of pectin and xylan to an otherwise diabetes-retarding semisynthetic diet affected microbial colonization of newly-weaned NOD mice, disturbed gut homeostasis and promoted diabetes development. These results help us to understand how diet and microbiota impact the regulation of the gut immune system in a way that might promote T1D in NOD mice.

A systematic review of the cost-effectiveness of targeted therapies for metastatic non-small cell lung cancer (NSCLC)

Background: Non-small cell lung cancer (NSCLC) imposes a substantial burden on patients, health care systems and society due to increasing incidence and poor survival rates. In recent years, advances in the treatment of metastatic NSCLC have resulted from the introduction of targeted therapies. However, the application of these new agents increases treatment costs considerably. The objective of this article is to review the economic evidence of targeted therapies in metastatic NSCLC. Methods: A systematic literature review was conducted to identify cost-effectiveness (CE) as well as cost-utility studies. Medline, Embase, SciSearch, Cochrane, and 9 other databases were searched from 2000 through April 2013 (including update) for full-text publications. The quality of the studies was assessed via the validated Quality of Health Economic Studies (QHES) instrument. Results: Nineteen studies (including update) involving the MoAb bevacizumab and the Tyrosine-kinase inhibitors erlotinib and gefitinib met all inclusion criteria. The majority of studies analyzed the CE of first-line maintenance and second-line treatment with erlotinib. Five studies dealt with bevacizumab in first-line regimes. Gefitinib and pharmacogenomic profiling were each covered by only two studies. Furthermore, the available evidence was of only fair quality. Conclusion: First-line maintenance treatment with erlotinib compared to Best Supportive Care (BSC) can be considered cost-effective. In comparison to docetaxel, erlotinib is likely to be cost-effective in subsequent treatment regimens as well. The insights for bevacizumab are miscellaneous. There are findings that gefitinib is cost-effective in first- and second-line treatment, however, based on only two studies. The role of pharmacogenomic testing needs to be evaluated. Therefore, future research should improve the available evidence and consider pharmacogenomic profiling as specified by the European Medicines Agency. Upcoming agents like crizotinib and afatinib need to be analyzed as well. © Lange et al.

Differentiated thyroid cancer with liver metastases: lessons learned from managing a series of 14 patients

International audience

Differential mechanisms of angiotensin II and PDGF-BB on migration and proliferation of coronary artery smooth muscle cells

Angiotensin II (Ang II) and platelet-derived growth factor-BB (PDGF-BB) are associated with excessive cell migration, proliferation and many growth-related diseases. However, whether these agents utilise similar mechanisms to trigger vascular pathologies remains to be explored. The effects of Ang II and PDGF-BB on coronary artery smooth muscle cell (CASMC) migration and proliferation were investigated via Dunn chemotaxis assay and the measurement of [3H]thymidine incorporation rates, respectively. Both atherogens produced similar degrees of cell migration which were dramatically inhibited by mevastatin (10 nM). However, the inhibitory effects of losartan (10 nM) and MnTBAP (a free radical scavenger; 50 μM) were found to be unique to Ang II-mediated chemotaxis. In contrast, MnTBAP, apocynin (an antioxidant and phagocytic NADPH oxidase inhibitor; 500 μM), mevastatin and pravastatin (100 nM) equally suppressed both Ang II and PDGF-BB-induced cellular growth. Although atherogens produced similar changes in NADPH oxidase, NOS and superoxide dismutase activities, they differentially regulated antioxidant glutathione peroxidase activity which was diminished by Ang II and unaffected by PDGF-BB. Studies with signal transduction pathway inhibitors revealed the involvement of multiple pathways i.e. protein kinase C, tyrosine kinase and MAPK in Ang II- and/or PDGF-BB-induced aforementioned enzyme activity changes. In conclusion, Ang II and PDGF-BB may induce coronary atherosclerotic disease formation by stimulating CASMC migration and proliferation through agent-specific regulation of oxidative status and utilisation of different signal transduction pathways.

Factores preditivos de linfoma no síndrome de Sjögren : a propósito de um caso clínico

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Can Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography Be Used As a Useful Method to Evaluate the Treatment Response to Neoadjuvant Therapy Combined With Sorafenib and Anti-VEGF in Children Diagnosed With Metastatical Bone Sarcoma?

Background: The prognosis is still poor for patients with a metastatic bone tumor and new treatment approaches (anti-VEGF and tyrosine kinase inhibitors vs) are therefore needed. Objectives: The aim of our study was to evaluate how the primary and metastatic lesions of our patients with a bone tumor were affected by these treatments and to determine the importance of the 18F-FDG PET method. Patients and Methods: Twenty metastatic bone tumor cases were included. Sorafenib and anti-VEGF were added to the standard treatment in cases with widespread metastatic disease at diagnosis or after neoadjuvant chemotherapy showing less than 90% tumor necrosis in the surgical sample. Positron emission tomography (PET) imaging was performed at diagnosis, the preoperative period following neoadjuvant chemotherapy, during postoperative follow-up, and when treatment was discontinued. Results: The primary treatment region median SUVmax level decreased from 7.35 to 2.5 in the living patients (n = 16) while there was no significant decrease in the patients who succumbed to the disease (P < 0.001). Comparison of the pre- and post-treatment metastasis region median SUVmax levels in patients with metastatic involvement showed a decrease from 2.1 to 0 in the surviving patients but only from 4.8 to 3.2 in the deceased patients (P < 0.01). Survival results indicated that 28.6% of the patients receiving classical treatment only died while all the patients receiving additional sorafenib and anti-VEGF survived. Conclusions: 18F-PET may be a useful technique before and during the follow-up of neoadjuvant treatment in pediatric metastatic bone tumor patients. The addition of sorafenib and anti-VEGF to classical treatment has a favorable contribution to the response and therefore the survival duration.

Anti-hyperprolactinemia mechanism of Radix bupleuri extract in rats

Purpose: To determine the mechanism underlying the anti-hyperprolactinemia effects of Radix bupleuri extract (RBE) in rats. Methods: Rats were divided into six groups (n=10 each group): healthy controls, untreated hyperprolactinemic rats, hyperprolactinemic rats treated with bromocriptine (0.6 mg/kg), and hyperprolactinemic rats treated with RBE (4.8, 9.6, or 19.2 g/kg). After 30 days, hypothalamic protein levels of dopamine D2 receptor, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP) were determined. Results: Dopamine D2 receptor levels were lower in untreated hyperprolactinemic rats than in healthy controls (p < 0.01), but this decrease was attenuated by RBE (p < 0.05). Elevated PKA levels in untreated hyperprolactinemic rats (0.61 ± 0.04 μg/ml, p < 0.01) were decreased by RBE (4.8 g/kg, 0.42 ± 0.03 μg/ml, p < 0.05; 9.6 g/kg, 0.33 ± 0.02 μg/ml, p < 0.01; 19.2 g/kg, 0.27 ± 0.03 μg/ml, p < 0.01). Similarly, elevated cAMP levels in hyperprolactinemic rats (2.4 ± 0.4 ng/ml) were decreased by RBE (4.8 g/kg, 1.8 ± 0.3 ng/ml, p < 0.05; 9.6 g/kg, 1.5 ± 0.3 ng/ml, p < 0.01; 19.2 g/kg, 1.2 ± 0.2 ng/ml, p < 0.01). Conclusions: RBE anti-hyperprolactinemia activity is mediated by dopamine D2 receptor signaling via the cAMP/PKA pathway.

Fibroblast growth factors:new insights, new targets in the management of diabetes

The fibroblast growth factor (FGF) family consists of 22 evolutionarily and structurally related proteins (FGF1 to FGF23; with FGF15 being the rodent ortholog of human FGF19). Based on their mechanism of action, FGFs can be categorized into intracrine, autocrine/paracrine and endocrine subgroups. Both autocrine/paracrine and endocrine FGFs are secreted from their cells of origin and exert their effects on target cells by binding to and activating specific single-pass transmembrane tyrosine kinase receptors (FGFRs). Moreover, FGF binding to FGFRs requires specific cofactors, namely heparin/heparan sulfate proteoglycans or Klothos for autocrine/paracrine and endocrine FGF signaling, respectively. FGFs are vital for embryonic development and mediate a broad spectrum of biological functions, ranging from cellular excitability to angiogenesis and tissue regeneration. Over the past decade certain FGFs (e.g. FGF1, FGF10, FGF15/FGF19 and FGF21) have been further recognized as regulators of energy homeostasis, metabolism and adipogenesis, constituting novel therapeutic targets for obesity and obesity-related cardiometabolic disease. Until recently, translational research has been mainly focused on FGF21, due to the pleiotropic, beneficial metabolic actions and the relatively benign safety profile of its engineered variants. However, increasing evidence regarding the role of additional FGFs in the regulation of metabolic homeostasis and recent developments regarding novel, engineered FGF variants have revitalized the research interest into the therapeutic potential of certain additional FGFs (e.g. FGF1 and FGF15/FGF19). This review presents a brief overview of the FGF family, describing the mode of action of the different FGFs subgroups, and focuses on FGF1 and FGF15/FGF19, which appear to also represent promising new targets for the treatment of obesity and type 2 diabetes.

Identification of Tyrosine Residues in Constitutively Activated Fibroblast Growth Factor Receptor 3 Involved in Mitogenesis, Stat Activation, and Phosphatidylinositol 3-Kinase Activation

Fibroblast growth factor receptor 3 (FGFR3) mutations are frequently involved in human developmental disorders and cancer. Activation of FGFR3, through mutation or ligand stimulation, results in autophosphorylation of multiple tyrosine residues within the intracellular domain. To assess the importance of the six conserved tyrosine residues within the intracellular domain of FGFR3 for signaling, derivatives were constructed containing an N-terminal myristylation signal for plasma membrane localization and a point mutation (K650E) that confers constitutive kinase activation. A derivative containing all conserved tyrosine residues stimulates cellular transformation and activation of several FGFR3 signaling pathways. Substitution of all nonactivation loop tyrosine residues with phenylalanine rendered this FGFR3 construct inactive, despite the presence of the activating K650E mutation. Addition of a single tyrosine residue, Y724, restored its ability to stimulate cellular transformation, phosphatidylinositol 3-kinase activation, and phosphorylation of Shp2, MAPK, Stat1, and Stat3. These results demonstrate a critical role for Y724 in the activation of multiple signaling pathways by constitutively activated mutants of FGFR3.