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Si le traitement du cancer du sein a fait des progrès remarquables au cours des dernières années, les options thérapeutiques en cas d’atteinte métastatique au niveau hépatique restent limitées, et associées à un pronostic sombre. Dans certains cas, la chirurgie ciblée des métastases hépatiques du cancer du sein peut être associée à des survies prolongées. A l’heure actuelle, il n’existe cependant pas de critères permettant de sélectionner ces patientes. L’identification de nouveaux biomarqueurs du comportement métastatique dans ces conditions représenterait donc une avancée importante. Dans cette thèse, nous nous sommes intéressés à la caractérisation clinique, histologique et biologique des métastases hépatiques chez les patientes atteintes d’un cancer du sein, et plus particulièrement aux profils de croissance histopathologiques des métastases hépatiques.Nous avons d’abord identifié deux profils de croissance histopathologiques :le profil de croissance de remplacement et desmoplastique. Nous avons rapporté des différences morphologiques, comme le contact direct entre les cellules cancéreuses et les hépatocytes dans le cas d’un profil de remplacement, ou une marge fibreuse isolant les cellules cancéreuses dans le cas d’un profil desmoplastique. Nous avons analysé les profils de croissance dans deux cohortes, une série rétrospective de patientes opérées pour métastases hépatiques et une série d’autopsie. Par rapport à la série chirurgicale, nous avons observé une augmentation de la prévalence du profil de remplacement dans les métastases hépatiques prélevées lors d’autopsies, suggérant que ce profil pouvait être associé à une maladie plus agressive. De façon cohérente avec cette observation, nous avons également montré la valeur pronostique de ces profils de croissance, le profil de remplacement étant significativement associé à une moins bonne survie globale et survie sans récidive que le profil desmoplastique. Parallèlement, nous avons mis en évidence une associat, Doctorat en Sciences biomédicales et pharmaceutiques (Médecine), info:eu-repo/semantics/nonPublished

La chirurgie reste le seul traitement potentiellement curatif chez les patients porteurs de métastases hépatiques (MH) d’origine colorectale (MHCCR) ou non-colorectale (MHNCR). Cependant, il n’existe actuellement pas de critères permettant de distinguer les patients qui vont bénéficier de la chirurgie de ceux chez qui des MH isolées sont la première manifestation d’une maladie disséminée. En conséquence, la majorité des patients récidive après la chirurgie. La recherche de nouveaux marqueurs permettant de caractériser individuellement le comportement métastatique chez ces patients représente donc un objectif majeur. Pour aborder cette question, nous nous sommes intéressés à des paramètres pouvant refléter le microenvironnement tumoral des MH, comme la captation de glucose (évaluée par FDG/PET scan) et le profil histologique de croissance (PHC).Chez les patients opérés pour MHCCR, nous avons observé des survies globales à 5 et 10 ans de 44.5 et 26%. Dans ces cas, aucun des facteurs de risque traditionnels ne permettait de distinguer les patients ayant bénéficié de la chirurgie (survie sans récidive ≥5 ans ou patients LTS) de ceux chez qui elle avait été inefficace (récidive non résécable <1 an ou patients ER). Dans cette population, nous avons montré que la captation de glucose des MH était plus élevée chez les patients ER, permettant d’établir un nouveau modèle de risque, défini comme le metabolic Clinical Risk Score (mCRS). L’étude du PHC des MHCCR a confirmé l’existence de 2 présentations principales: un profil desmoplastique (PHC-D), dans lequel les MH sont entourées par une réaction fibroblastique et un infiltrat immunitaire, et un profil infiltratif ou de remplacement (PHC-R) dans lequel les cellules cancéreuses infiltrent directement le foie, en l’absence d’infiltrat immunitaire. Chez les patients opérés pour MHCCR, nous avons montré le PHC-D représentait un facteur indépendant de bon pronostic et que la combinaison du mCRS avec le PHC permettait d’améliorer t, Doctorat en Sciences médicales (Médecine), info:eu-repo/semantics/nonPublished

Telomeres protect the ends of our chromosomes. The replicative immortality of cancer cells depends on the activation of a telomere maintenance mechanism: the telomerase or an alternative lengthening of telomeres (ALT) mechanism. ALT is activated in about 10% of tumors but this prevalence increases greatly in pediatric tumors. The latter are in need of targeted therapies but, to date, there is still no therapy targeting ALT. In this thesis, we identified TSPYL5 (testis-specific Y-encoded-like protein 5) as a critical protein for ALT+ cell viability, opening new perspectives for anti-ALT targeted therapies. We also established a mouse xenograft model with human ALT+ cancer cells to test the efficiency of future anti-ALT compounds. The lack of good tools for the diagnosis of ALT also led us to the development of a new robust test on tumor sections. Finally, we provided additional evidence that replicative stress induces some characteristics of ALT telomeres., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Protein kinase RNA-activated (PKR) and Double-stranded RNA-specific adenosine deaminase (ADAR1) are two double stranded RNA binding proteins, respectively involved in the antiviral response to viruses and in the metabolism of dsRNA molecules. PKR is a cellular protein kinase, that in response to dsRNA molecules generated during viral infections, gets activated and phosphorylates the translation initiation factor, eIF2a, leading to translational shutoff and apoptosis. As PKR thereby acts as a potent antiviral effector, many viruses evolved mechanisms to counteract its antiviral response. Previous studies showed that Theiler’s murine encephalomyelitis virus (TMEV), a cardiovirus belonging to the Picornaviridae family, can block PKR activation through the activity of its Leader (L) protein, an accessory protein of the virus known to block IFN gene transcription and perturb nucleocytoplasmic trafficking. In the first part of this thesis I contributed to a work showing that the L protein likely renders PKR insensitive to dsRNA molecules, possibly through the activation of cellular kinases. Next, we analyzed PKR phosphorylation modifications in the hope to identify potential phosphorylation sites responsible for PKR inhibition by TMEV L. We observed that the Ser6 residue located 3aa before the first double-stranded RNA binding motif (DRBM1) of PKR could be phosphorylated. A phospho-mimetic mutation of this site was inhibiting PKR activation after poly(I:C) transfection or viral infection, especially when combined to a phospho-mimetic mutation of the Ser97 residue, located 3aa before the second double- stranded RNA binding motif (DRBM2). We propose a model according to which phosphorylation occurring upstream of DRBMs would tighten the interaction of the DRBMs with the catalytic domain, blocking PKR in a closed conformation, and making it unable to be activated. ADAR1 is an editing enzyme, causing deamination of adenosines into inosines in dsRNA molecules, thus destabilizi, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Cancer immunotherapies, such as monoclonal antibodies (mAbs) directed against PD-1, aim at boosting immune responses against tumor cells. They have become a standard of care for several types of cancer. However, a majority of patients do not respond to current immunotherapies. Resistance to PD-1 blockade can in part be explained by the action of TGF-b1, an immunosuppressive cytokine activated notably by regulatory T cells (Tregs) via a mechanism that requires protein GARP. We developed antibodies against GARP:TGF-b1 complexes that block TGF-b1 activation by Tregs and we evaluated their anti-tumor efficacy in tumor-bearing mice. We observed that anti-GARP:TGF-b1 mAbs induce the regression of tumors otherwise resistant to anti-PD-1, and we showed that combined blockade of GARP:TGF-b1 and PD-1 can exert anti-tumor activity via multiple modes of action. This may prove important for the selection of cancer patients who could benefit from this novel form of immunotherapy in the clinics., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Uveal melanoma (UM) is the most common intraocular tumour in adults and despite surgical or radiation treatment of primary tumours, ~50% of patients progress to metastatic disease. Therapeutic options for metastatic UM are limited, with clinical trials having little impact. Here we perform whole-genome sequencing (WGS) of 103 UM from all sites of the uveal tract (choroid, ciliary body, iris). While most UM have low tumour mutation burden (TMB), two subsets with high TMB are seen; one driven by germline MBD4 mutation, and another by ultraviolet radiation (UVR) exposure, which is restricted to iris UM. All but one tumour have a known UM driver gene mutation (GNAQ, GNA11, BAP1, PLCB4, CYSLTR2, SF3B1, EIF1AX). We identify three other significantly mutated genes (TP53, RPL5 and CENPE).

High-grade B-cell lymphomas with MYC and BCL2 or BCL6 rearrangements are highly aggressive B-cell lymphomas called double-hit lymphomas (HGBL-DH). They are particularly refractory to standard treatments and carry a poor prognosis. Fragments of resected tumoral lymph nodes from two HGBL-DH patients were put in culture. Continuously proliferating cells were characterized and compared with the original tumors. In both cases, the proliferating cells and the tumor displayed MYC and BCL2 rearrangements. Both cell lines (called LB5848-LYMP and LB5871-LYMP) presented a high proliferation rate and were maintained in culture for more than one year. Upon injection in immunodeficient mice, LB5848-LYMP gave rise to lymphoid tumors. In vitro treatment of these cell lines with a BCL2-inhibitory drug (ABT-199) selectively stopped their proliferation. These new cell lines represent valuable tools for studying HGBL-DH and for the in vitro testing of candidate therapies targeting HGBL-DH. LB5848-LYMP is also suitable for similar experiments in vivo.

The essential amino acid tryptophan is metabolised along the kynurenine pathway by two enzymes, tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase 1 (IDO1). IDO1 was shown to be a potent immunosuppressor in a twofold way. It deprives lymphocytes of tryptophan and produces metabolites that inhibit cell proliferation and activity. In tumours, IDO1 can be either induced by pro-inflammatory stimuli in different cell types or be constitutively expressed by tumour cells. Those discoveries led to the development of IDO1 inhibitors to improve cancer immunotherapy. TDO has the same catalytic activity as IDO1, but is less active. It is primarily expressed by hepatocytes to regulate systemic tryptophan concentration. TDO2 mRNA was additionally found in tumours and the decidua (the endometrium during pregnancy). Metabolically active TDO is expressed by several tumour cell lines. In analogy to IDO1, experimental tumour models revealed an immunosuppressive function of TDO and its inhibition improved immune-mediated tumour growth control. We developed and validated highly specific mouse anti-human TDO antibodies and revealed by immunohistochemistry that TDO was expressed by different cell types in human tumours, normal tissues and the placenta. In the liver and hepatocarcinomas, TDO staining was found respectively in hepatocytes and in the tumour cells. Other normal tissues were devoid of TDO, but a high number of tumours originating from other tissues than the liver showed TDO staining in dispersed cells, ranging from 40% of kidney carcinomas to 97% of glioblastomas. Those cells were identified as pericytes and were often located in malformed vessels surrounding necrotic or haemorrhagic tumour areas in high-grade tumours. TDO-positive pericytes were also found in non-cancerous lung samples showing signs of inflammation. In the decidua and ectopic pregnancies, TDO was localised in some rare foetal pericytes and interstitial trophoblasts. Deeper analysis of glioblasto, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2019

MAGE genes are expressed in tumors but not in normal somatic tissues. When presented at the cell surface by HLA class I molecules, MAGE peptides can be recognized by cytolytic T lymphocytes. MAGE antigens have therefore gathered interest as cancer-specific immune targets. We observed in the tumor RNA-Seq database TCGA the expression of one MAGE gene, MAGEA9, in half of diffuse large B-cell lymphoma (DLBCL) samples. DLBCL derives from activated B lymphocytes in germinal centers. Other MAGE genes were silent, as opposed to what is seen in solid tumors. None of the MAGE genes were expressed by other types of lymphomas. We investigated the molecular mechanisms accounting for this highly selective expression. We found that, in DLBCL, MAGEA9 gene expression was correlated with demethylation of CpG dinucleotides in its promoter. Other MAGE promoters remained methylated. Thus, a selective mechanism causing MAGEA9 promoter demethylation is present in DLBCL, and accounts for its unique MAGE expression pattern. Using a validated anti-MAGEA9 antibody, we screened a series of DLBCL tumor samples, and confirmed that about half of them contained tumor cells expressing the MAGEA9 protein, often heterogeneously. MAGEA9 expression did not correlate with clinical parameters including patient survival, nor with common biological markers associated with DLBCL. These included defects in HLA class I presentation which, as we confirmed here, are particularly frequent in this type of lymphoma. Unexpectedly, we observed MAGEA9-expressing cells in germinal centers from non-cancerous tonsils. These cells did not express common phenotypic markers of germinal center B and T cells, follicular dendritic cells or macrophages. Thus, their precise nature remains uncertain. Intriguingly, MAGEA9-expressing cells were found in all the tonsil tissues from patients older than 8 years, but almost never in younger patients. We assessed whether DLBCL cells present HLA-bound MAGEA9 peptides that can be recogn, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2018

Breast cancer (BC) was not initially considered an immunogenic tumor; however, recent data show that immune-related factors are associated with patient prognosis and the response to treatment. Several large adjuvant clinical trials have shown that tumor infiltrating lymphocytes (TIL) are significantly associated with a better prognosis and can also predict responsiveness to pre-operative chemotherapy, particularly in the triple negative (TN) & HER2+ BC subtypes (Carsten Denkert et al. 2010; Loi et al. 2013a). Recently, the presence of ectopic lymph node-like structures characterized by distinct T and B cell zones, called tertiary lymphoid structures (TLS), were identified adjacent to the tumor (Gu-Trantien et al. 2013) in 60% of BC (Buisseret et al. 2017b) and linked with a good prognosis (Gu-Trantien et al. 2013). The mechanisms involved in TLS formation and activities and their impact on tumor immunity is relatively unknown. TIL infiltration and TLS formation are likely regulated, in part, by transcription factors (TF) that control cytokine/chemokine production within the tumor microenvironment (TME) (Pimenta and Barnes, 2014). One such TF, the forkhead box protein 1 (FOXP1) is abnormally expressed in various human tumors and has a known role in regulating immune cell functions. Contradictory data on FOXP1 expression together with a lack of information on its immune regulation led us to explore its role in this tumor type. The first part of this thesis research focused on FOXP1-mediated regulation in BC. Gene/protein analysis was examined in the four BC molecular subtypes, revealing its enriched expression in estrogen receptor positive (ER+) tumors (Luminal A/B). Luminal BC is generally less infiltrated compared with frequently high TIL infiltration in ER negative (ER-) tumors (i.e. HER2+ and TN) [reviewed in (Solinas et al. 2017a) and (Loi et al. 2014)]. We found that high FOXP1 expression in a cohort of untreated primary BC was significantly associated with a lo, Doctorat en Sciences biomédicales et pharmaceutiques (Médecine), info:eu-repo/semantics/nonPublished

Unlimited replicative potential is one of the hallmarks of cancer cells. In melanoma, hTERT (telomerase reverse transcriptase) is frequently overexpressed because of activating mutations in its promoter, suggesting that telomerase is necessary for melanoma development. We observed, however, that a subset of melanoma metastases and derived cell lines had no telomere maintenance mechanism. Early passages of the latter displayed long telomeres that progressively shortened and fused before cell death. We propose that, during melanoma formation, oncogenic mutations occur in precursor melanocytes with long telomeres, providing cells with sufficient replicative potential, thereby bypassing the need to re-activate telomerase. Our data further support the emerging idea that long telomeres promote melanoma formation. These observations are important when considering anticancer therapies targeting telomerase.

Despite the development of novel therapies and advanced surgical techniques, colorectal cancer (CRC) continues to be a disease with a poor prognosis, characterized by a high recurrence rate, low survival and chemotherapy resistance. Disease staging is often determined by clinical and histopathological parameters of the primary resected CRC tumour. However this classification provides limited prognostic information in estimating the patient outcome and response to therapy in a metastatic setting. The studies presented in this thesis aimed to characterize the tumour immune microenvironment in metastatic CRC and its relation to treatment, tumour response and patient prognosis. Using a cohort of patients with curative resections of CRC metastases, our studies indicated that the variability of the tumour immune microenvironment was related to the metastastic process and proportional to the size (intra-metastatic variability) and the number of metastases (inter-metastatic heterogeneity). Moreover, the immune infiltrate was heterogenous in primary tumours and CRC metastases and closely related to patient survival. Preoperative systemic treatment was associated with a higher immune infiltration of cytotoxic and memory T cells, along with increased PD1+ cells. This effect was observed in metastases but not in the synchronously resected primary tumours and much more associated with epidermal growth factor receptor monoclonal antibodies (EGFR mAbs). Regarding the characterization on the tumour immune microenvironment in mCRC and the treatment impact of selected treatment (EGFR mAbs), our investigations open possible new avenues for the therapeutic management of CRC, often considered a challenging tumour with respect to immunotherapy., (MED - Sciences médicales) -- UCL, 2017

Unlimited replicative potential is one of the hallmarks of cancer cells. In melanoma, hTERT (Telomerase Reverse Transcriptase) is frequently overexpressed because of activating mutations in its promoter, suggesting that telomerase is necessary for melanoma development. We observed however that a subset of melanoma metastases and derived cell lines had no telomere maintenance mechanism. Early passages of the latter displayed long telomeres that progressively shortened and fused before cell death. We propose that, during melanoma formation, oncogenic mutations occur in precursor melanocytes with long telomeres, providing cells with sufficient replicative potential, thereby bypassing the need to re-activate telomerase. Our data further support the emerging idea that long telomeres promote melanoma formation. These observations are important when considering anticancer therapies targeting telomerase.

Despite impressive clinical success, cancer immunotherapy based on immune checkpoint blockade remains ineffective in many patients due to tumoral resistance. Here we use the autochthonous TiRP melanoma model, which recapitulates the tumoral resistance signature observed in human melanomas. TiRP tumors resist immunotherapy based on checkpoint blockade, cancer vaccines or adoptive T-cell therapy. TiRP tumors recruit and activate tumor-specific CD8+ T cells, but these cells then undergo apoptosis. This does not occur with isogenic transplanted tumors, which are rejected after adoptive T-cell therapy. Apoptosis of tumor-infiltrating lymphocytes can be prevented by interrupting the Fas/Fas-ligand axis, and is triggered by polymorphonuclear-myeloid-derived suppressor cells, which express high levels of Fas-ligand and are enriched in TiRP tumors. Blocking Fas-ligand increases the anti-tumor efficacy of adoptive T-cell therapy in TiRP tumors, and increases the efficacy of checkpoint blockade in transplanted tumors. Therefore, tumor-infiltrating lymphocytes apoptosis is a relevant mechanism of immunotherapy resistance, which could be blocked by interfering with the Fas/Fas-ligand pathway.

PURPOSE: Autologous monocyte-derived dendritic cells (DCs) electroporated with synthetic mRNA (TriMixDC-MEL) are immunogenic and have antitumor activity as a monotherapy in patients with pretreated advanced melanoma. Ipilimumab, an immunoglobulin G1 monoclonal antibody directed against the cytotoxic T-lymphocyte-associated protein 4 receptor that counteracts physiologic suppression of T-cell function, improves the overall survival of patients with advanced melanoma. This phase II study investigated the combination of TriMixDC-MEL and ipilimumab in patients with pretreated advanced melanoma. PATIENTS AND METHODS: Thirty-nine patients were treated with TriMixDC-MEL (4 × 10(6) cells administered intradermally and 20 × 10(6) cells administered intravenously) plus ipilimumab (10 mg/kg every 3 weeks for a total of four administrations, followed by maintenance therapy every 12 weeks in patients who remained progression free). Six-month disease control rate according to the immune-related response criteria served as the primary end point. RESULTS: The 6-month disease control rate was 51% (95% CI, 36% to 67%), and the overall tumor response rate was 38% (including eight complete and seven partial responses). Seven complete responses and one partial tumor response are ongoing after a median follow-up time of 36 months (range, 22 to 43 months). The most common treatment-related adverse events (all grades) consisted of local DC injection site skin reactions (100%), transient post-DC infusion chills (38%) and flu-like symptoms (84%), dermatitis (64%), hepatitis (13%), hypophysitis (15%), and diarrhea/colitis (15%). Grade 3 or 4 immune-related adverse events occurred in 36% of patients. There was no grade 5 adverse event. CONCLUSION: The combination of TriMixDC-MEL and ipilimumab is tolerable and results in an encouraging rate of highly durable tumor responses in patients with pretreated advanced melanoma.

Melanoma is not only one of the most immunogenic cancers but also one of the most effective cancers at subverting host immunity. The role of T lymphocytes in tumor immunity has been extensively studied in melanoma, whereas less is known about the importance of B lymphocytes. The effects of plasma cells (PCs), in particular, are still obscure. The aim of this study was to characterize pathological features and clinical outcome of primary cutaneous melanomas associated with PCs. Moreover, we investigated the origins of the melanoma-associated PCs. Finally, we studied the outcome of patients with primary melanomas with PCs. We reviewed 710 melanomas to correlate the presence of PCs with histological prognostic markers. Immunohistochemistry for CD138 and heavy and light chains was performed in primary melanomas (PM) and in loco-regional lymph nodes (LN), both metastatic and not metastatic. In three PM and nine LN with frozen material, VDJ-rearrangement was analyzed by Gene Scan Analysis. Survival analysis was performed on a group of 85 primary melanomas >2 mm in thickness. Forty-one cases (3.7%) showed clusters/sheets of PCs. PC-rich melanomas occurred at an older age and were thicker, more often ulcerated and more mitotically active (P<0.05). PCs were polyclonal and often expressed IgA in addition to IgG. In LN, clusters/sheets of IgA+ PCs were found both in the sinuses and subcapsular areas. Analysis of VDJ-rearrangements showed the IgA to be oligoclonal. Melanomas with clusters/sheets of PCs had a significantly worse survival compared with melanomas without PCs while, interestingly, melanomas with sparse PCs were associated with a better clinical outcome (P=0.002). In conclusion, melanomas with sheets/clusters of PCs are associated with worse prognosis. IgG and IgA are the isotypes predominantly produced by these PCs. IgA oligoclonality suggests an antigen-driven response that facilitates melanoma progression by a hitherto unknown mechanism.Modern Pathology advance o

The clinical efficacy of immunostimulatory antibodies targeting the PD-1 pathway in cancer is likely mediated by CD8 T cells recognizing tumor-specific antigens. Whether breast carcinomas (BCs) are infiltrated by such cells is not known. We wished to obtain evidence for the presence of tumor-specific CD8 T cells in primary BCs. Random sets of CD8 T cell clones were derived from 6 BCs that we screened for recognition of candidate tumor-specific antigenic peptides, which were encoded either by mutated genes or by cancer-germline genes. One of these sets contained 6 different clones that recognized 4 mutant peptides, thus demonstrating that some primary BCs are immunogenic. The corresponding tumor displayed a DNA mismatch repair deficiency associated with a high number of mutations compared to the other 5 tumors. In these 5 tumors, the estimated number of presented mutant antigenic peptides was very low or zero, likely explaining the absence of detectable tumor-specific T cells., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2016

Ipilimumab (Ipi) improves the survival of advanced melanoma patients with an incremental long-term benefit in 10-15 % of patients. A tumor signature that correlates with this survival benefit could help optimizing individualized treatment strategies.

Cutaneous melanoma is a very aggressive skin cancer with high propensity to metastasize. It is generally admitted that metastasis formation requires the acquisition of a telomere maintenance mechanism. As melanomas derive from melanocytes in which the expression of hTERT catalytic subunit of telomerase is repressed, reactivation of telomerase to acquire immortality often requires acquisition of one of the two recurrent and -believed to be- mutually exclusive C>T somatic mutations in hTERT promoter. C228T or C250T mutations, detected in about 80% of melanoma cell lines, create binding sites for GABP transcription factor. Here, we analyzed hTERT promoter mutations and telomere maintenance in a first series of lymph node metastases from ten melanoma patients and in cell lines freshly derived from these metastases. C228T and/or C250T mutations in hTERT promoter were found in eight cell lines that all expressed hTERT mRNA and were also detected in paired melanoma metastases. One cell line lacked expression of hTERT while another one failed to express hTR. Both telomerase-deficient cell lines were also negative for ALT features and displayed continuous telomere shortening in culture. Huge genomic instability was observed at late passages, characterized by sister chromatid/chromosome fusions, before massive cell death arose. Ectopic hTR overexpression in hTRneg cell line allowed continuous proliferation of the cells, showing that telomere shortening was the cause of cellular crisis. Intriguingly, one of these two telomeraseneg tumors was the most aggressive one from the series as, within less than one year, multiple visceral metastases appeared and patient died. Xenograft experiments with both telomerasepos and telomeraseneg cell lines in immuno-compromised mice are ongoing and preliminary results will be presented. We analyzed telomere maintenance mechanisms in additional metastases and primary melanoma cell lines and will discuss our first results. Our data provide evide

Background: Ipilimumab (Ipi) improves the survival of advanced melanoma patients with an incremental long-term benefit in 10-15 % of patients. A tumor signature that correlates with this survival benefit could help optimizing individualized treatment strategies. Methods: Freshly frozen melanoma metastases were collected from patients treated with either Ipi alone (n: 7) or Ipi combined with a dendritic cell vaccine (TriMixDC-MEL) (n: 11). Samples were profiled by immunohistochemistry (IHC), whole transcriptome (RNA-seq) and methyl-DNA sequencing (MBD-seq). Results: Patients were divided in two groups according to clinical evolution: durable benefit (DB; 5 patients) and no clinical benefit (NB; 13 patients). 20 metastases were profiled by IHC and 12 were profiled by RNA- and MBD-seq. 325 genes were identified as differentially expressed between DB and NB. Many of these genes reflected a humoral and cellular immune response. MBD-seq revealed differences between DB and NB patients in the methylation of genes linked to nervous system development and neuron differentiation. DB tumors were more infiltrated by CD8+ and PD-L1+ cells than NB tumors. B cells (CD20+) and macrophages (CD163+) co-localized with T cells. Focal loss of HLA class I and TAP-1 expression was observed in several NB samples. Conclusion: Combined analyses of melanoma metastases with IHC, gene expression and methylation profiling can potentially identify durable responders to Ipi-based immunotherapy., SCOPUS: ar.j, info:eu-repo/semantics/published

Tryptophan catabolism by indoleamine 2,3-dioxygenase (IDO1) is a physiological immunoregulatory mechanism often hijacked by tumors. Our recent extensive study of IDO1 protein expression in human tissues showed expression in mature dendritic cells and in pulmonary and placental endothelial cells. IDO1 was also expressed in 56% of tumors, either by tumoral, stromal or endothelial cells. These results and reagent will guide the clinical development of IDO1 inhibitors for cancer therapy.

Tryptophan catabolism by indoleamine 2,3-dioxygenase 1 (IDO1) plays a key role in tumoral resistance to immune rejection. In humans, constitutive expression of IDO1 has been observed in several tumor types. However, a comprehensive analysis of its expression in normal and tumor tissues is still required to anticipate the risks and potential benefits of IDO1 inhibitors. Using a newly validated monoclonal antibody to human IDO1, we performed an extensive immunohistochemical analysis of IDO1 expression in normal and tumor tissues. In normal tissues, IDO1 was expressed by endothelial cells in the placenta and lung and by epithelial cells in the female genital tract. In lymphoid tissues, IDO1 was expressed in mature dendritic cells with a phenotype (CD83+, DC-LAMP+, langerin-, CD123-, CD163-) distinct from plasmacytoid dendritic cells. Importantly, IDO1-expressing dendritic cells were not enriched in tumor-draining lymph nodes, in contrast with previously reported findings. IDO1-expressing cells were observed in a large fraction (505/866, 58%) of human tumors. They comprised tumor cells, endothelial cells, and stromal cells in proportions that varied depending on the tumor type. Tumors showing the highest proportions of IDO1-immunolabeled samples were carcinomas of the endometrium and cervix, followed by kidney, lung, and colon. This hierarchy of IDO1 expression was confirmed by gene expression data mined from The Cancer Genome Atlas database. Expression of IDO1 may be used to select tumors likely to benefit from targeted therapy with IDO1 inhibitors.

BRAF inhibitors elicit rapid antitumor responses in the majority of patients with BRAF(V600)-mutant melanoma, but acquired drug resistance is almost universal. We sought to identify the core resistance pathways and the extent of tumor heterogeneity during disease progression. We show that mitogen-activated protein kinase reactivation mechanisms were detected among 70% of disease-progressive tissues, with RAS mutations, mutant BRAF amplification, and alternative splicing being most common. We also detected PI3K-PTEN-AKT-upregulating genetic alterations among 22% of progressive melanomas. Distinct molecular lesions in both core drug escape pathways were commonly detected concurrently in the same tumor or among multiple tumors from the same patient. Beyond harboring extensively heterogeneous resistance mechanisms, melanoma regrowth emerging from BRAF inhibitor selection displayed branched evolution marked by altered mutational spectra/signatures and increased fitness. Thus, melanoma genomic heterogeneity contributes significantly to BRAF inhibitor treatment failure, implying upfront, cotargeting of two core pathways as an essential strategy for durable responses.

L’immunothérapie du cancer se distingue des traitements classiques en oncologie (chirurgie, radiothérapie et chimiothérapie) par le fait qu’elle cible non pas les cellules cancéreuses, mais agit sur le système immunitaire du patient cancéreux, en essayant de stimuler son action contre la tumeur. Nous savons que les patients cancéreux montrent des réponses lymphocytaires T spontanées contre des antigènes présents sur leur tumeur, et nous comprenons mieux pourquoi ces réponses ne parviennent pas à contrôler la progression tumorale, du moins chez les patients avancés. Plusieurs approches thérapeutiques sont développées: les vaccinations par antigènes tumoraux, le transfert adoptif de lymphocytes T anti-tumoraux amplifiés ex vivo, et les anticorps immunostimulants. Des progrès thérapeutiques très prometteurs ont été obtenus récemment, en particulier en terme de réponses prolongées. L’immunothérapie est en passe de trouver une place de choix dans l’arsenal thérapeutique en oncologie, [The surge of cancer immunotherapy] Cancer immunotherapy can be distinguished from standard treatments in oncology (surgery, radiotherapy, and chemotherapy) by the fact that it does not target the tumor cells themselves but rather the cancer patient’s immune system by trying to enhance its antitumoral activity. We recognize that cancer patients develop spontaneous T-lymphocyte responses directed against antigens present on their tumor cells, and we now better understand why these immune responses fail to control disease progression, at least in advanced-stage patients. Several therapeutic approaches are being developed, such as vaccination with tumor antigens, adoptive transfer of ex vivo amplified T-lymphocytes, and immunostimulating antibodies, with promising therapeutic progress made recently, particularly in terms of prolonged responses. Immune therapy is finding its place in the therapeutic arsenal against cancer.