201 research outputs found
Etude du rôle des lymphocytes T régulateurs dans la régulation des réponses immunes antitumorales induites par vaccination
No full textLe système immunitaire est capable de rejeter une tumeur, même si l'interaction entre système immun et tumeurs est et reste complexe. Contrôler à long terme la croissance de la tumeur est un challenge, probablement suite à divers mécanismes de tolérance centrale et périphérique. Différentes approches d'immunothérapie du cancer ont été et sont toujours développées. Nous avons, au laboratoire, investigué et démontré, dans le cadre de deux différents modèles tumoraux murins, les capacités thérapeutiques d’une nouvelle stratégie de vaccinations combinées associant des injections de cellules dendritiques (DC) et de cellules tumorales sécrétrices de GM-CSF.<p><p>Notre travail de thèse a consisté à poursuivre l'étude de cette stratégie de vaccins combinés en étudiant plus particulièrement le rôle des lymphocytes T régulateurs (Treg) dans l'efficacité thérapeutique des vaccinations. <p>Les Treg regroupent différentes populations cellulaires immunosuppressives dérivées du thymus qui jouent un rôle clé dans le maintien de la tolérance périphérique. Les Treg naturels dont le mécanisme de suppression principal nécessite un contact cellule-cellule, expriment de façon constitutive les molécules de surface CD4, CD25 et CTLA-4 mais le marqueur le plus spécifique est le facteur de transcription Foxp3 qui est indispensable à leur développement et à leur fonction suppressive. Dans un premier temps, nous avons donc caractérisé les Treg de rat pour l'expression de Foxp3 et la nature et spécificité antigénique de leur fonction suppressive. Nos résultats démontrent d’une part, une expression de Foxp3 restreinte aux LT CD25+ natifs et liée à une fonction suppressive s'exerçant par contact cellule-cellule et d’autre part, une spécificité antigénique non-restreinte de ces Treg. <p><p>Ensuite, nous avons utilisé ce modèle de vaccination associant des injections de DC et de cellules tumorales sécrétrices de GM-CSF pour analyser comparativement les réponses immunes induites chez les rats vaccinés guéris ou non-guéris et les rats contrôles non vaccinés et identifier les paramètres cruciaux conduisant à l'éradication de la tumeur. Nos résultats ont montré que la principale différence entre rats vaccinés guéris et non guéris ne réside pas dans l'induction de réponses cytotoxiques systémiques spécifiques de la tumeur. Par contre, la guérison est associée à la persistance d'une réponse systémique LT CD4+ TH1 ainsi qu'au recrutement important en intratumoral de LT CD8+ cytotoxiques lié à une faible proportion relative de Treg. <p><p>Comme dans la majorité des études publiées chez l'animal, les DC utilisées dans ces vaccins combinés ont été générées à partir de rats naïfs, par différenciation de précurseurs de la moëlle osseuse en présence de GM-CSF seul. Par analogie avec les vaccins DC administrés aux patients cancéreux, nous avons aussi dérivé des DC à partir de la moëlle osseuse de rats porteurs d’une tumeur (TUM+) et nous avons constaté que ces mêmes vaccins combinés montraient in vivo une efficacité thérapeutique nettement moins bonne que leurs équivalents naïfs. Nous avons établi que cette différence d’efficacité était liée à la présence de Treg fonctionnels dans les vaccins DC dérivés de rats TUM+. Puis, nous avons établi le lien entre la présence de Treg dans les vaccins DC TUM+ et leur moins bonne efficacité thérapeutique en montrant qu'un traitement in vivo des rats TUM+ au témozolomide (TMZ) avant de générer les vaccins DC résultait in vitro, en une moindre expression de Foxp3 et une fonction suppressive diminuée et in vivo, en une bien meilleure survie des rats vaccinés.<p><p>Enfin, dans le but d’une utilisation future en clinique, nous avons développé une approche simplifiée ‘tout in vivo’ de notre modèle de vaccinations combinées, en utilisant la tumeur localement irradiée in vivo comme source d’antigène pour des DC autologues injectées en péri-tumoral et un apport exogène de GM-CSF. Nous avons utilisé des adénovirus associés recombinants porteurs du gène du GM-CSF (AAV1-GM-CSF) pour transduire la tumeur in vivo. Ces injections intratumorales d’AAV1-GM-CSF ont montré de bons résultats en vaccinations combinées puisque 60% des rats ont pu être guéris d’une tumeur 9L pré-implantée. Nous avons ensuite expérimenté l’enrobage des AAV1-GM-CSF dans un polymère biocompatible et thermosensible, le poloxamère, avant de les injecter en intratumoral, sans observer de meilleur effet thérapeutique. Cependant, nous avons constaté que l'utilisation du poloxamère pour enrober du GM-CSF recombinant permettait d'améliorer nettement la survie des rats vaccinés par comparaison à l'utilisation de GM-CSF recombinant seul.<p><p>La stratégie de vaccinations combinées que nous avons largement explorée et validée chez le rat serait une alternative intéressante à développer en clinique, particulièrement en combinaison avec un traitement permettant d'éliminer les Treg à la fois dans les vaccins et chez les patients vaccinés.<p>Doctorat en Sciences biomédicales et pharmaceutiquesinfo:eu-repo/semantics/nonPublishe
Receptor tyrosine kinases as a target for therapy in WTBRAF melanoma
No full textMelanoma is divided into four genomic subtypes: BRAF, NRAS, NF1, and Triple-WT. Integrative analysis reveals enrichment of RTK alterations (mutations, focal amplifications, and complex structural rearrangements) as a feature of the WTBRAF group. Non-BRAF mutant melanoma patients have limited treatment options with only 30% responding to checkpoint inhibitors. Several efforts were dedicated to preventing tumor growth and metastases in WTBRAF melanoma by targeting RTKs that regulate cell proliferation, invasion, and migration. Melanoma had been considered a radioresistant tumor showing broad shoulder in survival fraction assays mainly attributed to high repair efficacy and the presence of pigment. Of note, it was shown in several cancers that ionizing radiation (IR) promotes RTK activity (radiation-induced intracellular translocation of RTKs) which enhances DNA repair. Conversely, RTK inhibition could impede repair kinetics of radiation-induced DNA damage and thus improve tumor response to ionizing radiation. This relation of RTK-RT indicates that a possible combination of RT and RTK inhibition could be more interesting than previously thought. Compared to other DNA damaging or anti-mitotic agents, inhibition of tumor specific-receptor tyrosine kinases could be a rational approach for combined radiotherapy to assume tumor control with lesser side effects and a better quality of life. For this reason, we aimed to assess the benefit of combining RTK inhibition and radiotherapy in non-BRAF mutant melanoma and depict the associated pathways and mechanisms. Firstly, we found that specific inhibition of c-Met (HGFRi, Crizotinib), or DNA repair agent inhibitor (PARPi, Olaparib) resulted in a significant enhancement of melanoma radiosensitivity, indicating the possible association between radioresistance and c-Met activity or PARP activity in melanoma. Moreover, we found that RT mediates nuclear translocation of Met that associates to PARP, two hours following RT in melanoma. Interestingly, the nuclear enzymatic activity of PARP following RT can be reversed when combined with c-Meti (Crizotinib), also Ko of Met mediate enhanced response to PARP inhibitor and RT in melanoma. This indicates, that c-Met translocates to the nucleus under radiotherapy and activates PARP that confers melanoma radioresistance. Consequently, targeting MET and PARP under radiotherapy resulted in a significant synergistic decrease in cell survival and increase of cell death compared to METi or PARPi and/or RT both in vitro and in vivo. Our results shed the light on a new promising combinatorial approach in non-BRAF mutant melanoma that deserves further translational investigation, particularly that RTK inhibition is considered of particular importance in the WTBRAF melanoma subgroups showing a short/limited clinical benefit. While running large screenings with RTK inhibitors, a c-Kit inhibitor, dasatinib, attracted our attention because 1) it is the most active among c-Kit inhibitors, due to its ability to bind both active and inactive conformations of the receptor; 2) despite all expectations, its use as a single agent in melanoma showed limited clinical benefit; 3) unexpectedly and despite complete inhibition of both MAPK and PI3K/AKT pathways, we observed less effect at high dasatinib concentrations but yet can be found in patients’ blood during clinical trials. A deeper investigation of other important pathways in melanoma revealed a significant increase of the main transcription factor in melanocytes, MITF, and of its downstream target, particularly, Bcl-2 under high dasatinib concentrations. As the canonical pathway to activate MITF proceeds through the stem cell factor and its receptor kinase c-Kit but also through cAMP/CREB, we searched for a possible off-target effect for dasatinib and found that it inhibits SIK2, which is known to phosphorylate CRTC3. The latter mediates CREB transcription and activation of MITF. A series of validation studies involving selective Bcl-2 inhibition either by ABT-199 or Bcl-2 knockout, was able to restore melanoma cells sensitivity to dasatinib, associated with pieces of evidence (FSK, pigmentation, acquired resistance model…), highly supporting the involvement of MITF and Bcl-2 axis as a mechanism of resistance induced by dasatinib itself that may have contributed to its modest efficacy in various clinical trials.Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)info:eu-repo/semantics/nonPublishe
Survival follow-up and ipilimumab retreatment of patients with advanced melanoma who received ipilimumab in prior phase II studies
No full textIn phase II studies, ipilimumab continues to demonstrate durable, long-term survival at a follow-up of 5-6 years in a proportion of patients with advanced melanoma. In some patients, ipilimumab retreatment can reestablish disease control with a safety profile that is comparable with that observed during ipilimumab induction. Further studies are needed to determine the contribution of ipilimumab retreatment to overall survival.This report provides a survival update at a follow-up of > 5 years (5.5-6 years) for patients with advanced melanoma who previously received ipilimumab in phase II clinical trials. Safety and efficacy data following ipilimumab retreatment are also reported.Patients who previously received ipilimumab 0.3, 3, or 10 mg/kg in one of six phase II trials (CA184-004, CA184-007, CA184-008, CA184-022, MDX010-08, and MDX010-15) were eligible to enroll in the companion study, CA184-025. Upon enrollment, patients initially received ipilimumab retreatment, extended maintenance therapy, or were followed for survival only. Overall survival (OS) rates were evaluated in patients from studies CA184-004, CA184-007, CA184-008, and CA184-022. Safety and best overall response during ipilimumab retreatment at 10 mg/kg were assessed in study CA184-025.Five-year OS rates for previously treated patients who received ipilimumab induction at 0.3, 3, or 10 mg/kg were 12.3%, 12.3%-16.5%, and 15.5%-28.4%, respectively. Five-year OS rates for treatment-naive patients who received ipilimumab induction at 3 or 10 mg/kg were 26.8% and 21.4%-49.5%, respectively. Little to no change in OS was observed from year 5 up to year 6. The objective response rate among retreated patients was 23%. Grade 3/4 immune-related adverse events occurred in 25%, 5.9%, and 13.2% of retreated patients who initially received ipilimumab 0.3, 3, and 10 mg/kg, with the most common being observed in the skin (4.2%, 2.9%, 3.8%) and gastrointestinal tract (12.5%, 2.9%, 3.8%), respectively.At a follow-up of 5-6 years, ipilimumab continues to demonstrate durable, long-term survival in a proportion of patients with advanced melanoma. In some patients, ipilimumab retreatment can re-establish disease control with a safety profile that is comparable with that observed during ipilimumab induction. Further studies are needed to determine the contribution of ipilimumab retreatment to OS.NCT00162123. © The Author 201
Development and Validation of a Predictive Model for Metastatic Melanoma Patients Treated with Pembrolizumab Based on Automated Analysis of Whole-Body [F-18]FDG PET/CT Imaging and Clinical Features
No full textThis research was funded by Innoviris grant number BHG/2017-PFS-15
Vemurafenib in patients with BRAFv(600) mutated metastatic melanoma: an open-label, multicentre, safety study
No full textTBackground: The orally available BRAF kinase inhibitor vemurafenib, compared with dacarbazine, shows improved response rates, progression-free survival (PFS), and overall survival in patients with metastatic melanoma that has a BRAFV600 mutation. We assessed vemurafenib in patients with advanced metastatic melanoma with BRAFV600 mutations who had few treatment options. Methods: In an open-label, multicentre study, patients with untreated or previously treated melanoma and a BRAFV600 mutation received oral vemurafenib 960 mg twice a day. The primary endpoint was safety. All analyses were done on the safety population, which included all patients who received at least one dose of vemurafenib. This report is the third interim analysis of this study. This study is registered with ClinicalTrials.gov, number NCT01307397. Findings: Between March 1, 2011, and Jan 31, 2013, 3226 patients were enrolled in 44 countries. 3222 patients received at least one dose of vemurafenib (safety population). At data cutoff, 868 (27%) patients were on study treatment and 2354 (73%) had withdrawn, mainly because of disease progression. Common adverse events of all grades included rash (1592 [49%]), arthralgia (1259 [39%]), fatigue (1093 [34%]), photosensitivity reaction (994 [31%]), alopecia (826 [26%]), and nausea (628 [19%]). 1480 (46%) patients reported grade 3 or 4 adverse events, including cutaneous squamous cell carcinoma (389 [12%]), rash (155 [5%]), liver function abnormalities (165 [5%]), arthralgia (106 [3%]), and fatigue (93 [3%]). Grade 3 and 4 adverse events were reported more frequently in patients aged 75 years and older (n=257; 152 [59%, 95% CI 53–65] and ten [4%, 2–7], respectively) than in those younger than 75 years (n=2965; 1286 [43%, 42–45] and 82 [3%, 2–3], respectively). Interpretation: Vemurafenib safety in this diverse population of patients with BRAFV600 mutated metastatic melanoma, who are more representative of routine clinical practice, was consistent with the safety profile shown in the pivotal trials of this drug.James Larkin, Michele Del Vecchio, Paolo A Ascierto, Ivana Krajsova, Jacob Schachter, Bart Neyns, Enrique Espinosa, Claus Garbe, Vanna Chiarion Sileni, Helen Gogas, Wilson H Miller Jr, Mario Mandalà, Geke A P Hospers, Ana Arance, Paola Queirolo, Axel Hauschild, Michael P Brown, Lada Mitchell, Luisa Veronese, Christian U Bla
Clinical trials with MRNA electroporated dendritic cells for stage III/IV melanoma patients
No full textAutomated threshold selection on whole-body 18F-FDG PET/CT for assessing tumor metabolic response
No full textPembrolizumab for the treatment of uveal melanoma: A case series
No full textUveal melanoma is a rare disease. Up to 50% of the patients will develop metastases for which the treatment options are limited. No randomized controlled data for the treatment of uveal melanoma patients are available. In this study we describe the clinical course of nine uveal melanoma patients included in the pembrolizumab expanded access program (EAP) in Belgium. Nine uveal melanoma patients were treated in the EAP with 2mg/kg pembrolizumab every 3 weeks. Patients received pembrolizumab as first or second-line treatment. Baseline characteristics and tumor responses were prospectively collected. During a median follow-up of 40 weeks, the estimated median PFS was 18 weeks (95% CI 0.7-35) and median OS was 46 weeks (95% CI 33-59%). Four patients had stable disease (SD) for more than 20 weeks (PFS of 21, 22, and 27 weeks respectively) and 1 patient presented with SD for 119 weeks. No objective responses according to irRC were observed. One grade 3 hepatitis occurred which was reversible with the administration of high doses oral corticosteroids. Even though treatment with pembrolizumab is well tolerated, clinical benefit is disappointing. Nevertheless long-term diseases control can be achieved in selected cases
Automated threshold selection on whole-body 18F-FDG PET/CT for assessing tumor metabolic response
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